Nemesis

E = 10⁷ Mt, I = 45°, Target = Tertiary Andesite

The meteor comes in high over the Gulf of Mexico, in a blaze of light which darkens the noon sun from the Florida Keys to Jamaica.

Two thousand miles to the north, and four minutes before he dies, Colonel Peter “Foggy” Wallis is in his office watching television. The office itself is dark and comfortable, a restful place. It is made of steel. It sits on springs whose coils are made from steel rods three inches in diameter. Steel walkways connect the office to another fourteen similar, self-contained rooms. The entire office complex is contained within a giant cavern hollowed out from a granite mountain. Steel pins up to thirty feet long are driven into the cavern walls, and steel mesh is suspended below the ceiling high overhead, to protect him from dislodged boulders should a hostile giant ever strike the mountain. Access is through steel doors, each weighing twenty-five tons, and along a tunnel fourteen hundred feet long.

The television picture comes from a camera twenty-five thousand miles above the surface of the Earth. It is beamed down into a huge antenna near Alice Springs, relayed across two oceans, cabled a thousand feet into the bowels of the Rock and then up into the colonel’s television set for his personal perusal.

The colonel pulls open a Seven-Up and sips at the fizzy lemonade. An oil well is burning in Iran. Its long smoky trail, bright in the infrared, has been longer at every shift for days, and now it has at last reached the northern Himalayas. Otherwise nothing much has changed. He flicks a button and the black night-time Pacific now appears, ringed by lights. To the left, the Sea of Japan glows softly, illuminated from within by the lights of the Japanese shrimp fishermen. Hawaii appears as a central dot. Idly, he flicks a switch and the dot resolves itself into a string of coastal lights dominated by Honolulu on Oahu and Hilo on Big Island.

Suddenly the lights fail; the VDUs dissolve into snow and die. A chorus of surprised profanity begins to emerge from the dark, but almost immediately the lights flicker and come back on, and the screens return to life.

“Now what was that?” Wallis asks nobody in particular. Rapidly, he scans the screens, flicking through the signals from sensors on land, sea, air and space. They reveal nothing: no anomalies, no intrusions. On the other hand, power cuts have never happened before.

“David, check it out.”

While the young major sitting to the left of Wallis speaks into a telephone, Wallis himself taps out a command on the console in front of him. A mass of coloured symbols obscures his god’s eye view of the world. He types again, and all but a handful of the symbols vanish.

Over the Barents Sea, just north of Novaya Zemlya, a patrol of ageing Tupolev Blackjack bombers is high over the pack ice and the seals; another three hours on that bearing and they would invade Canadian air space, heading south for the Kansas silos. A flock of MiG 23s is heading out over the sea of Japan: six hours, if only they had the range, and they would reach Hawaii.

Only ten minutes ago a big KH-11 satellite passed over Kirovsk on the Kola peninsula, recording the Badgers, Back-fires and MiGs which swarm like bees in and out of the four military air bases surrounding the city; elsewhere inside the mountain, careful men watched their movements; they collated and analysed, using massive computers: alert for the unusual, paranoid towards the unexpected. But the computers detected no strangeness in the patterns, and the careful men relaxed.

For twenty years following the collapse of the Empire, Kirov has been a ghost city. The bees flew to distant Eastern bases, or were executed by order of disarmament treaties. Some of the careful men were reassigned to tinpot dictatorships; most left to take up lucrative jobs with McDonnell Douglas or IBM. They no longer collated and analysed. But then came the food riots; and the Black Sea mutiny, which spread like a plague first to the Pacific Fleet and then to the elite Tamanshaia and Kanterimov divisions; and the chaotic elections in which Vladimir Zhirinovsky, heavily supported by the Red Army, swept to victory. The man who had publicly threatened to nuke Japan and the United Kingdom, and whose declared intention was to expand the Russian Empire by force, was in the Kremlin.

And now the Badgers are back in Kola, and the careful men have returned to the mountain.

Stuff like that doesn’t bother Wallis in the slightest. It just makes his job more interesting.

He types again. Thirty assorted ships in formation. Slava and nuclear-powered Kirov cruisers, skirting Norway and heading for Scapa Flow.

So what?

A handful of dots appears on the screen, obtained at vast expense from hydrophone arrays sprinkling the seabed along the GIUK Gap, the choke-point bridging Greenland, Iceland and the Orkneys. A couple of ancient Yankees and a Foxtrot are heading out into the North Atlantic. Yesterday, the combat team followed a Typhoon heading north, twenty-four thousand tons of displacement whose signals were soon lost in the clicking of shrimps and the cry of whales.

The hell with it. There are no abnormal movements; the computers are seeing no suspicious patterns. It has been a long shift, and the colonel, three minutes and twenty seconds before he dies, leans back in his chair, stretches and yawns.

It strikes ground in the Valley of Morelos, a hundred miles south of Mexico City. It is sparse, hard land, a countryside of dry, stony tracks, overloaded burros, maize fields and giant cacti.

In the time it takes Wallis to yawn the asteroid has vaporised, ploughed to a halt ten miles under the ground and generated a ball of fire five miles wide and a hundred thousand degrees hot. Shock waves carrying four million atmospheres of pressure race outwards from the fireball, ancient granites flow like water.

“Sir, the generator people say it was some sort of ground surge. It seems the national grid got it too.”

“Any reason for it?”

“They’re checking it out. There’s a big storm complex around Boulder.”

“Okay. You’re looking bushed, boy.”

The major grins. “It’s the new baby, sir. She never sleeps.”

“The first sixteen years are the worst,” Wallis says.

In the time it takes to discuss the major’s baby the fireball scours out a hole fifty miles wide from the Mexican countryside. The hole is ten miles deep and a sea of white hot lava pours upwards through the cracked and fissured mantle. Around the rim of the big hole, a ring of mountains builds up from the torrent of rock. Molten mountains are hurtling into the stratosphere, leaving white-hot wakes of expanding air. The blast moves out over the map. Mexico City vanishes, an irrelevant puff of smoke.

The ground waves too race outwards from the hole, leaving a wake of fluidized rubble. The rubble is forming into ripples and the ripples, tumbling rocky breakers reaching five miles into the disturbed sky, roar towards Panama, Guatemala and the United States.

All the way up the Pacific seaboard the morning mists are rolling in. Foghorns wail round Vancouver island like primeval monsters, a thick white shroud blankets San Francisco and the traffic is snarling up in downtown LA. But now electric currents surge overhead as the fireball pierces the stratosphere, rising back through the hole punched out by the asteroid, and electrons spiral back and forth between the Earth’s magnetic poles. Spears and curtains burst into the black Arctic sky and dance a silent, frenzied reel, while the frozen wastelands below reflect the shimmering red and green. Counterflowing currents surge over the Americas; cables melt, telephones die, radios give out with a bang, traffic stops in the streets.

Just over the border from Mexico, early morning shoppers in Tucson, Yuma and San Diego see long black fingers crawling up from the horizon to the south. The fingers reach out for the zenith. And as the shoppers stop to watch, the blue-white fireball too rises over the horizon like a bloated sun, and with it comes the heat. Everything combustible along the line of sight burns; and all living things along the line of sight crisp and shrivel.

And in Wallis’s office, apocalypse stirs.

“Sir, we have a system interrupt on OTH,” says the major. “We’re losing Chesapeake and Rockbank.”

“Roger.”

“Hey Colonel, I’m not getting a signal from the DSPs.” This from Lieutenant Winton, the solitary woman on the team.

“Sir, Ace has just bombed out.”

“What the…?” Wallis says as the images in front of him dissolve once again into snow.

“Sir. We’ve lost Alaska, Thule and Fylingdales. Colonel… we’ve lost all coverage on the Northern Approaches.” Wallis goes cold; he feels as if a coffin lid has suddenly opened.

“Okay, soldier, keep calm. Get the general down here. Major, would you get me Offutt? Pino, interrogate REX, get a decision tree on screen Five.” Wallis issues the orders in a level voice.

“Sir, are we under attack?” The nervous question comes from Fanciulli, a tough, grey-haired sergeant to Wallis’s right.

“Pino, where are the warheads?”

“Yeah but we got some sort of EMP…”

“Nuts; all we got is cable trouble.”

“Negative, sir.” It is Lieutenant Winton again, her small round face unusually pale. “We have tropospheric forward scattering modes up top, and we’ve lost on VHF. There’s some sort of massive ionospheric disturbance.”

“Sunspots?”

“No way, sir.”

“Colonel we have reduced bandwidth on all—”

An alarm cuts into the chamber and a light flashes red. Somebody wails. And Pino, his face wax-like, mutters a string of profanities as he types rapidly on a keyboard.

“Colonel, Screen Three.”

Covering the walls of the office are enormous screens. Mostly these show arcane lists of data — coded refuelling points, the tracks of satellites in orbit, numbers of aircraft aloft — but one of them is instantly comprehensible. It is a map of the USA. And on the map, red lights are beginning to wink.

“The General, sir.” Wallis looks up at the glass-fronted observation room. General Cannon has appeared, flanked by a civilian and a second general: Hooper, Chairman of the Joint Chiefs of Staff. Wallis snatches up a telephone, but Cannon, impassive as an Indian chief, ignores the urgent ringing.

One of the screens has changed. There is a blurred, jerky picture. Somebody is pointing a camera from an airplane cockpit. They are flying high over a city and the plane is tilted so that the camera can look down. There are skyscrapers, and long straight roads with cars, and parks. The camera pans and there is an ocean wave. It is almost level with the aircraft, and it covers half the city. Here and there, on the lower slopes of the wave, the tops of the skyscrapers protrude, some of them already slowly tilting over. Wallis stares in utter disbelief. The wave towers high over the remaining buildings; it looks frozen, but white specks are falling off the top and tiny cars are dotted here and there in the broad rising sheet of water. Someone shouts, in a voice edging on panic, That’s San Diego! Wallis kills the alarm.

The camera points backwards. It is unsteady, like an amateur movie. The ocean stretches into the distance and the wave with it. There is a long smoky contrail and a glimpse of wing, and racing up from behind is a churning black wall as tall as the sky, and then the camera shakes and there is a helmet in close-up, and inside a young black face, eyes staring in fright, is shouting silently, and then the screen goes blank.

The major gabbles into the phone. Fanciulli, tears streaming down his cheeks, points to one of the big screens. New red lights are winking on virtually every second. Winton is saying Sir, why doesn’t the General answer. Then:

“Offutt, sir.” Wallis snatches up another telephone, the blue one. But already new messages are flashing; lists of names are tumbling down the screens faster than they can be read. Wallis, his ear still to the telephone, stares at the map of the USA. The red lights, each one a Strategic Air Command base scattered to the winds, have formed a broad front, slowly creeping up from the south.

The decision tree is up. REX is requesting more data.

A voice on the telephone. It speaks in harsh, staccato tones. Wallis forces his attention from the advancing wave and listens. He replies, hearing in astonishment that his own voice is shaking and frightened: “Sir, I agree a threat assessment conference… no sir, we lack dual phenomenology… negative, negative… not if we go by the book… we have no evidence of hostile warheads or hostile intent… agreed… agreed… sir, how the fuck would I know? Some sort of blast coming from Mexico… I urgently advise we do not get Eagle into Kneecap… repeat do not get the Chief aloft… no sir, keep the B-2s on the tarmac, their wings would just tear off… sir?”

The line has gone dead.

There is a stench of fresh vomit. Wallis feels a tug on his sleeve. The major has apparently lost the power of speech; he is staring ahead, as if looking at his own death. Wallis follows the young man’s line of vision. The wave of red lights is now passing in a long arc from California through Kansas to Virginia. Its progress is slow but steady over the map. It has almost reached the Rock.

“Sir, we’re buttoned up. Hatches closed and filtration on. Sir?”

But Wallis is looking helplessly up at the observation room. The civilian and the generals look stonily down.

Then it reaches them.

Abduction

Something.

The young man opened his eyes with a start, some dream fading from memory, and stared into the dark. Unaccountably, his heart was thumping in his chest.

At first he could make out only the flap-flap of the canvas inches from his head, and the Whee! of the wind around the guy ropes. And then it came again, a distant roar, deep and powerful, coming and going over the noises of the storm. Puzzled, he strained his ears.

Then it dawned.

Avalanche!

He shot out of his sleeping bag and tugged frantically at the rope lacing up the front of the hurricane tent. The knot was an impenetrable tangle and the noise was growing in intensity. Desperately he scrabbled in the dark for a bread-knife, found it, cut the rope, hauled back the canvas and pitched head-first into the dark night.

The blizzard hit him with a force which made him gasp.

For a panicky moment he thought to run into the dark but then remembered where he was: on a mountain ridge next to a precipitous drop. And the roar was coming from the gully below.

He dived back to the tent, and felt for the paraffin lamp and a box of matches. The wind blew the match out; and the next and the next. The fourth match worked, and he hooked the glowing lamp up to an aluminium pole. He looked around. Snowflakes like luminous insects were hurtling from the void into a circle of light about ten yards in radius around the tent; he could just make out the edge of the ridge, about twenty yards away.

A cone of bluish-white light rose out of the gully, passing left to right before disappearing from the man’s line of vision.

Avalanches don’t come with blue lights.

The man’s legs were shaking, whether with cold or relief he didn’t know. The light cone was drifting up and down in a sweeping pattern, snow hurtling through the beam.

It occurred to him that a man in a Glencoe blizzard, dressed only in boxer shorts, probably had a life expectancy of minutes. Already his back was a mass of sharp, freezing pain. Hastily, he reached in for corduroy trousers and sweater, pulled them on and slipped into climbing boots. He tripped over untied laces, picked himself up and ploughed through deep snow to the edge of the ridge overlooking the Lost Valley. The sweater, he realized, bought him at most another five minutes: the wind was going through it like a chainsaw through butter.

The light cone rose and approached. It was scanning the mountain slopes. Suddenly light flooded the ground around him. An intense spotlight rose into space and approached; the roar became overwhelming; the ground vibrated. Dazzled, the man caught a glimpse of a whirling rotor passing straight overhead. A giant insect, a yellow flying monster of a thing, circled him and then sank towards a sloping patch of snow about thirty yards away. It almost vanished in the blizzard kicked up by its rotors. It tried to settle down, backed off, tried again, but its undercarriage slithered over the snow and the machine slid perilously sideways towards the edge of a precipitous drop. The pilot gave up and rose over the man’s head.

A spider emerged in silhouette from the side of the machine, and began to sink down on a swaying thread. It settled on to the knee-deep snow within arm’s length of him, resolving itself into a young airman in a khaki-coloured flying suit. “Flt Lt A.W.L. Manley” was stencilled on his helmet. “Doctor Webb?”

Webb stared in astonishment, and nodded.

“You’re coming upstairs. Quickly, please.”

Five hundred miles to the southeast, in Paris, the Atlantic storm had softened from the harsh reality of a potentially lethal blizzard to a bitter, wet, gusty wind.

As was his custom, the professor left his apartment at 7:30 a.m. precisely. Dark clouds swirled just above the rooftops, a newspaper streaked along the road and a solitary pigeon was attempting a speed record; but he was well clad in trenchcoat and beret, and as usual he walked the two hundred yards to the Café Pigalle. There he took off his sodden trench-coat and sat at the marble bar. Without waiting to be asked, Monique served him two strong espresso coffees and a croissant with butter and strawberry jam, which he consumed while watching the early morning Parisians scurrying past.

At eight fifty, as he always did, he set out along the Rue d’Alesia, jumping over the flowing gutters and avoiding the bow waves from passing trucks. He turned off at the church of St-Pierre de Montrouge and headed briskly towards the Sorbonne. He had no reason even to notice the man purchasing cigarettes at the kiosk. The man was squat and bulky, with grey hair close-cropped almost to the scalp. His bull neck was protected from the rain by the pulled-up collar of his sodden jerkin. A policeman stood on the edge of the pavement next to the kiosk, his back to the professor, watching the flow of traffic through the little waterfall pouring from the brim of his sodden cap.

As the professor drew level with the kiosk, the squat man suddenly turned. “Professor Leclerc?”

Startled, Leclerc looked into the man’s eyes, but they showed no expression. “Who are you?”

From the corner of his eye the professor saw a big Citroën pull up, the rear door open and another man step out: thin, tight-lipped, with eyes set back in his head. Suddenly, and instinctively, the professor was afraid.

“Please come with us, Professor.”

“Why? What is this?”

“I do not know. A matter of national security. Get into the car.”

Thinking assassination, Leclerc turned to run; but powerful arms seized him, held him in a painful neck lock. He wriggled furiously, his beret falling to the ground, but another pair of hands twisted an arm behind his back. Half-choked, he tried to shout but he was pushed into the back seat of the car, one man on either side of him. Leclerc forced his arm free and hammered on the rear window. The policeman turned away a little more, his back squarely to the professor. The driver took off swiftly, cutting into the path of a taxi. The man at the kiosk tidied his newspapers, the Parisians scurried by, and the policeman, water streaming down his shiny cape, tossed the beret into a litter bin while keeping his eye firmly on the glistening rush-hour traffic.

The warm ocean which powered the Atlantic storm was also dumping its energy into the far north of the planet; here the air, turned away from the sun, was exposed to interplanetary cold; here, it responded to the Earth’s ancient rotation, and circulated anticlockwise around the Arctic Ocean: a huge blizzard howled out over the pack ice and the seals, the killer whales and the sunless wastelands.

The blizzard rampaged over the pole, down through Alaska and the North West Territories, passed over a thousand miles of Baffin Island, and howled through a few Inuit hunting groups who knew it as the Chinook, a hostile force which drove itself up nostrils and winkled out tiny gaps in snow goggles. The blizzard was still a blizzard over Quebec Province and New York State but, far from the oceanic heat engine, it was beginning to die. Even so, swirling along Broadway and Times Square, the dying snowstorm could still send late evening theatre crowds scurrying into warm bars, and traffic cops into a state of sullen paranoia.

Passing over the Great Lakes, the wind went into a rapid decline until, in Baltimore, Maryland and Washington, it finally died, leaving only snowflakes drifting down on sleeping houses: a traditional Christmas, all Bing Crosby, Silent Night, and Christmas trees glittering from a million dark windows.

In at least one Maryland suburban home, however, the night was neither still nor silent, and the owner barely heard the chime of the doorbell above the party hilarity and the raucous dance music. Reluctantly, Hilary Sacheverell detached herself from her white-haired, tall dancing partner, and weaved a path through the party. In the hallway she stepped over a young couple sitting together on the floor, backs to the wall. She opened the door, a smile half-formed on her face in expectation of late arrivals. A gust of freezing night air wafted around her exposed shoulders and she shivered.

Two men, in their thirties, one white, one black. Strangers. Snow sprinkled their heads and dark coats like tinsel decoration. A black Buick convertible had somehow snaked its way through the Mercs and Dodges which cluttered the driveway. A third man, in the Buick, just discernible through its dark windscreen. The woman was suddenly alert.

“Mrs. Sacheverell?” the black man asked.

She nodded uneasily.

“Is your son here?”

“Which one?”

“We’re looking for Doctor Herbert Sacheverell, ma’am.”

“Herby is here,” she said. “Is there a problem?”

“If we could just have a word with him.”

A hardness about the eyes; a professional alertness. Some instinct prevented her from inviting them in from the bitter cold. “Wait a moment, please.”

It was a full minute before she found a skeletally thin, middle-aged man with thick spectacles and red, spiky hair seated at the kitchen table with the Ellis woman. A near-empty bottle of Jim Beam stood between them. The girl had her elbows on the table and was resting her head in cupped hands, staring into Sacheverell’s blue eyes with open admiration. Sacheverell, thus encouraged, was extolling the merits of legalizing cannabis, itemizing the points with the aid of his bony fingers.

“Herby, two men for you,” Mrs. Sacheverell said, looking through the Ellis female. “They look sort of official. Have you been naughty?”

Herby shook his head in bewilderment. He stood up carefully, oriented himself towards the open kitchen door and navigated towards it with exaggerated steadiness.

“Enjoying the party?” Mrs. Sacheverell asked.

“Oh yes, Mrs. S. Herby is really good to me.”

“Tell me, have you tried anything for that big spot on your chin?” Mrs. Sacheverell asked, curling her lips into a smile.

The smile was returned. “I’m using a cream. It’s supposed to be good for wrinkles too — I’ll hand it in to you some time.”

“That would be lovely, dear. Do keep drinking.”

A minute later, the doorbell rang again. Herb Sacheverell stood between the two men. He was tight-lipped, and his face was white and strained. “I’ll be gone a few days. Urgent business.”

She glanced in alarm at the men on either side of her son.

“There’s something going on here. Who are these people?”

“Mom, it’s okay. But one thing. It’s important that you tell nobody about this. If anyone asks, friends have turned up and I’m taking a few days’ holiday.”

Hilary Sacheverell’s suspicion was overlaid by her sense of the practical. “Let me pack a suitcase for you.”

“There’s no time. They’ll look after me. Now I have to go.”

Hilary Sacheverell watched the dark Buick snake through the driveway and then, on the road, accelerate swiftly away. She wended a path back to the living room, a smile firmly fixed on her face.

“You’ve got the wrong man. I’m not a medical doctor.”

“This isn’t a rescue mission. If you’re Webb, you’re wanted on board.”

“Who are you people?”

“We don’t have a lot of time, sir!” the airman shouted.

“The hell with you!” Webb shouted back.

“Sir, I am authorized to use force.”

“Don’t try it. On whose authority?”

“We don’t have a lot of time, sir.” The airman took a step forward. Webb instinctively turned to run but, looking into the whirling blizzard and the blackness beyond, immediately saw that such an action would be a lethal folly. He raised his hands in an angry gesture of surrender and furrowed his way through the snow back to his tent. The down-draught from the big rotor was threatening to flatten it and the guy ropes were straining at the pegs. Inside, the noise of the flapping canvas was deafening and the paraffin lamp was swaying dangerously. Papers were fluttering around the tent. He gathered them up, grabbed a laptop computer, turned off the lamp and ploughed back towards the lieutenant, tightly gripping papers and computer. The airman pointed towards the white blizzard and the man ran forwards into it; under the big rotor, the downdraught was fierce, and he felt as if he was being freeze-dried. The airman shouted “Hold on!” and slipped a harness around him. Then Webb’s feet were off the ground and he was gripping the papers fiercely as the winch swung and spun them upwards through the gusting wind.

A Christmas tree, tied tightly, and with baubles attached, lay along the length of the machine. Half a dozen sacks with “Santa” in red letters lay on the floor. Two civilians, men in their fifties, were at the back of the helicopter. They were identically dressed in headphones, grey parkas and bright yellow lifejackets. Webb recognized one of them but couldn’t believe his eyes.

The airman pointed and he tottered to the front, flopping down on the chair behind the pilot. The wet sweater felt horrible against his skin.

The pilot turned. He had a red, farm-boy face and seemed even younger than his navigator. His helmet identified him as W.J. Tolman, and “Bill T.” was printed on the back of his flying suit.

Manley said, “It’s force eight out there, mister; we’re not supposed to fly in this. Put on the lifejacket!”

Webb looked out. Daylight was trying to penetrate the gloom. Across the glen, he could just make out sheets of snow marching horizontally against the backdrop of granite mountains. The top of the ridge opposite was hidden in dark, sweeping cloud. He began to feel faint.

The pilot pulled on the collective and the big machine rose sharply upwards. Webb’s stomach churned. Tolman looked over his shoulder. “What gives with this trip? Are you some sort of James Bond?”

The helicopter began to buck violently. Webb looked down and glimpsed his hurricane tent, a tiny black dot against the massive, white top of the Big Herdsman. Then the machine was roaring over the Lost Valley and they were rising bumpily towards the Three Sisters. As it reached the summit it was hit by the unshielded force of the blizzard. It lurched and tilted on its side, throwing Webb against the fuselage. “Jesus Holy Mary Mother of Christ!” the pilot yelled. Then the helicopter had righted and was thrusting roughly into the wind, its wipers clicking in vain against a wall of white, while another wall, made of granite, skimmed past.

Webb stared out. His faintness had given way to terror. Below, white Highland peaks came and went through dark scudding clouds; and then they were passing along Loch Linnhe and the Sound of Mull; and then they were heading out over an ocean made of white churning milk; and the waves on the milk moved in slow stately progression; and they were bigger than houses.

The pilot turned again. “I was supposed to meet a nurse tonight,” he said accusingly. “Knockers like melons and game for anything. James bloody Bond on a secret mission I do not need. By the way, your pals from SMERSH are waiting.”

The young man made his way unsteadily to the back of the machine. “You don’t mind if I smoke, Webb?” asked the Astronomer Royal, lighting up a Sherlock Holmes pipe. He was buckled into a seat at a small circular table screwed into the metal floor. There was no telling what lay behind his blue eyes and Webb judged that the man on the chair next to him wasn’t an artless rustic either. He collapsed into a seat opposite, buckled in and put on the headphones in front of him.

“This is the fellow,” said the AR.

“Walkinshaw,” the stranger said. He looked like a headmaster, half-moon spectacles mounted on a grey skull-like head. It was a civil servant’s handshake: prudent, cautious, economical. The helicopter was into its stride, moving briskly if roughly about five hundred feet above the big waves. The civil servant glanced forward at the airmen; they too were wearing earphones.

“I expect you’re wondering what’s going on, Webb,” said the Astronomer Royal, unscrewing the lid of a flask.

“The question did flicker across my mind, Sir Bertrand,” said Webb angrily. “I have, after all, just been kidnapped.”

“Don’t exaggerate. The Sea King is transporting us to Skye.”

“Skye?”

“Skye. Where Walkinshaw and I will be dropped off. You, however, will continue on to Iceland.”

“Iceland?”

“Webb, try not to sound like a parrot. I am informed that we have only twenty minutes to brief you. Six of these have already gone.” A match flared and Webb waited while the King’s Astronomer got up more smoke. “Father smoked an ounce a day, lived to be ninety. Walkinshaw here is from some God Knows What department of the Foreign Office. Webb, we have a problem.”

“Just a moment, Sir Bertrand. Sorry to interrupt your Christmas vacation, Doctor Webb.” Walkinshaw nodded at the sheets of A4 paper, covered with handwritten mathematical equations, which the man was still unconsciously clutching. “Although you seem to be on a working holiday.”

“Will someone tell me what is going on here?” Webb said. He was trembling, through a compound of shock, fear, anger and cold. He folded the papers up and slipped them into his back pocket.

“First there are a couple of formalities. Number One.” Walkinshaw leaned forward and passed over a little plastic card. Webb held it towards the nearest window. There was a Polaroid photograph of the civil servant, looking like a funeral undertaker, over an illegible signature. Next to the photo was a statement that

Webb nodded warily and returned the card.

“And Number Two.” The civil servant reached into his briefcase again and handed over a sheet of paper. “An E.24, quite routine. If you would just sign there.”

The Astronomer Royal unzipped his parka. “It’s hot in here,” he said, holding out a pen. Webb ignored it and read

Webb felt the hairs prickling on the back of his head. On the back, he read that if any person having in his possession or control any secret official code word, password, sketch, plan, model, article, note, document, or information which relates to or is used in a prohibited place or any thing in such a place, or which has been made or obtained in contravention of this Act, or which has been entrusted in confidence to him by any person holding office under His Majesty or which he obtained or to which he has had access owing to his position as a person who holds or has held a contract made on behalf of His Majesty, or as a person who is or has been employed under a person who holds or has held such an office or contract, communicates… or uses… or retains… or fails to take reasonable care of, or so conducts himself as to endanger the safety of, the sketch, plan, model, article, note, document, secret official code or password or information, then that person shall be guilty of misdemeanour.

He handed it back unsigned.

The Astronomer Royal made no attempt to hide his annoyance; his teeth audibly tightened on his pipe. He returned the pen to an inside pocket, and glanced quickly at Walkinshaw. The latter nodded briefly.

Tolman’s voice cut sharply into the intercom: “Do not smoke. Put that pipe out immediately.”

Sir Bertrand continued to puff. Bleak Atlantic light from a window had turned his wrinkled face into a mountainous terrain. The helicopter was filling with blue smoke. He said, speaking carefully: “The Americans suspect that an asteroid has been clandestinely diverted on to a collision course with their country.”

Webb stared at him, aware of a sudden light-headedness as he struggled to take it in. “What? You could be talking a million megatons.”

“Webb, I’m aware that you think I’m just an establishment hack. However even I can multiply a mass by the square of its velocity.” Sir Bertrand pushed a little metal stubber into his pipe. “The Americans informed their NATO allies late last night — the Eastern bloc partners excepted of course — and the Foreign Office requested my assistance at four o’clock this morning. But as you know asteroids are not my field.”

“An asteroid like that would devastate half the planet. This has to be wrong.”

“If only.”

“Which asteroid?”

“You’re missing the point,” said the AR. “The idea is that you tell us.”

Webb tried to grasp what he had just been told. The AR and the civil servant watched him closely. “Okay, you’ve scared me. What you’re asking is insane. It would be easier to find a needle in a haystack.”

“Nevertheless it must be done and done quickly. The Americans will need to find some way of diverting it.”

“You must have some information about it.”

The AR shook his head. “None whatsoever. All we can say is that at some unknown future time it will manifest itself over American skies as a meteor of ferocious intensity.”

“An asteroid impact on North America could leave two hundred million dead. Suppose I fail, or make a wrong identification? I can’t take responsibility for that.”

“There is nobody else. And I would prefer a more respectful tone.”

Webb felt his mouth beginning to dry up. “I’m sorry, Sir Bertrand, but the moment I say yes, I’m swallowed up in God knows what. Get someone else.”

The Astronomer Royal’s voice dripped with acid. “I know this will sound absurdly quaint in this day and age, Webb, but there is the small matter of one’s obligations to humanity.”

“Hold on a minute. I went to Glen Etive for a reason.” He tapped his back pocket with the papers. “Listen. I’m on the verge of something. I think I can put some meat into general relativity. You know GR is just a phenomenology, it lacks a basis in physical theory, and that Sakharov conjectured…”

The Astronomer Royal’s tone was icy. “You were instructed not to spend time on speculative theoretical exercises.”

“I happen to be on leave, trying to do some real science for a change. You have a problem with an asteroid? Get someone else to look into it.”

The Astronomer Royal took the pipe from his mouth, his face wrinkling with angry disbelief. He made to speak but Walkinshaw quickly raised his hand. “Please, Bertrand.” The civil servant lowered his head, as if in thought. Then he leaned forward, to be heard above the engine. “Doctor Webb, I apologize for the melodramatic descent from the skies, but the fact is that we are engaged in a race, with an asteroid, which we must not lose.” The helicopter was tilting and Webb gripped the table. He sensed that his face was grey. “The Americans are trying to put together a small team to look into this. They have specifically requested a British contribution. We do not know when impact will occur but it must be clear that time is vital. We must get you to New York instantly. As Sir Bertrand says, there is nobody else in this country.”

The AR, at last, poured a black liquid into the plastic lid of the flask. Webb took it and sipped at the warm tea. His stomach was churning and he was beginning to feel nauseous. “Who diverted the asteroid?”

The civil servant remained silent.

“There’s some risk attached to this, right?” Webb peered closely at Walkinshaw, but the man had the eyes of a poker player.

The AR turned to Walkinshaw. “A wasted journey,” he said contemptuously. “Turn the Sea King back. I’ll get Phippson at UCL.”

“Phippson? That idiot?” Webb said in astonishment.

The AR waited.

“But the man’s a total incompetent.”

The AR cleared his throat.

“He couldn’t find the full moon on a dark night!”

The AR stubbed the tobacco in his pipe, a smirk playing around his lips.

“Damn you, Sir Bertrand,” Webb said.

Sir Bertrand removed his pipe, exposed his teeth and emitted a series of loud staccato grunts, his shoulders heaving in rhythm. Webb was enveloped by a wave of nicotine-impregnated breath. He gulped the tea and handed the flask lid back to the Astronomer Royal, who was grinning triumphantly.

Walkinshaw’s eyes half-closed with relief. “Very well. The country is grateful etcetera. Now the quickest route from here is the polar one. After this briefing—” Walkinshaw glanced at his watch “—which must end in four minutes, we will be dropped off on a quiet beach near the Cuillins. You will carry straight on to Reykjavik Airport. There you will board a British Airways flight to New York. It’s the quickest route we could devise from this Godforsaken land.”

He pulled out a buff envelope from a briefcase. “Your ticket, some dollars, an American Express number on which you can draw, and a passport.”

“How did you get my photograph?”

“You would be amazed, and at four o’clock this morning. You are Mister Larry Fish, a goldsmith. A precaution in case unfriendly eyes are watching the movements of asteroid people. What do you know about gold, Webb?”

The Sea King was sinking fast, and Webb’s stomach rose in his diaphragm.

“Atomic number seventy-nine, isn’t it? The least reactive metal but alloys with mercury.”

Walkinshaw assimilated this answer. Then he said in a toneless voice, “In no circumstances hold any sort of conversation with anyone en route.”

“Unfriendly eyes,” Webb said. He felt almost paralysed with fear. “So there is some risk attached to this?”

“My goodness no,” said Walkinshaw blandly.

“If there is trouble nevertheless?”

“Never heard of you. You’re a crackpot.”

“A popular opinion in some circles anyway,” Webb replied, giving the Astronomer Royal a look. The AR stared unflinchingly back.

The long backbone of the Cuillins was hidden by low, fast cloud sweeping in from the Atlantic. They stepped out into low, fast sleet sweeping in from the Atlantic. Fifty yards away on the black sand, a dark insect was poised to jump. It was bigger than a house. It had mysterious protrusions, and a row of windows along its dark side, and huge twin rotors throwing spirals of water into the wind. The sand under the Sikorsky was rippling and the Sea King was suddenly a child’s toy.

Webb stared in alarm at the monstrous thing.

Walkinshaw shouted, “The Air Force will make sure you catch the plane at Reykjavik. Sign the credit card as Larry Fish. Any expenditures must be accounted for but you shouldn’t need it.”

“Then why give me it?”

“A precaution,” was the enigmatic response. “I am informed that you know the Goddard Institute at Broadway. You are expected there around now. Still, they tell me you can beat the Sun at polar latitudes. Something to do with the Earth turning, but we pay you people to know about things like that, don’t we, Bertrand?”

“What about my tent?”

“Webb,” the AR replied with a show of infinite patience, “Have you quite grasped the situation? The issue here is not your scientific research, nor your evident fear of flying nor the fate of your blasted tent. The issue is the survival of the West. His Majesty’s Air Force have laid on travel gear in the Chinook, and His Majesty’s Astronomer will personally dismantle your tent and return it to your office.”

“I’ll be missed at the Institute,” Webb pleaded.

“The hell you will!” the Astronomer Royal roared. “Nobody knows what you do in that damned basement all day. Anyway, you sent a note saying you’ve extended your leave. My secretary does signatures.”

“I’m not getting into that contraption!” Webb finally shouted, but he knew he would.

“Just find the asteroid, Webb,” the Astronomer Royal shouted back. “And quickly! And keep your mouth shut!”

The freezing rain drove into the Astronomer Royal’s wrinkled face, and he screwed up his eyes as the massive helicopter rose and tilted over the sea. He watched as it dwindled upwards and vanished into the clouds. He puffed reflectively on his pipe, the wind blowing a thin stream of smoke across the beach.

Walkinshaw looked worried. “Bertrand, are you sure about this? What sort of man spends Christmas alone on a mountain, in a blizzard, calculating?”

“A hermit, of course. Speaking as his Director, he’s a nightmare.”

“In what way?”

“He’s restless, the very devil to control. Needs a woman if you ask me. He keeps diverting from well-established lines of research into cosmological speculation. There’s no funding for stuff like that these days, and anyway nobody quite understands what he’s about. However he pursues his ideas with great exuberance and determination.”

“Family?”

“I know little of it except that he comes from a large, poor one with no sort of academic background.”

“Then I understand him,” Walkinshaw declared. “A large family with little privacy will make him invent his own private space, a world in which he can daydream. Hence the cosmological speculation. And the need to compete with siblings will make him pursue his own ends with determination. Throw in an exceptional intelligence and there you have him.”

A deeply sceptical expression came over the AR’s face. “Very neat, Walkinshaw, wonderfully glib. I don’t suppose you’re into palmistry as well as amateur psychology?”

“His evident unworldliness has the same source. There is no great ingenuity without an admixture of dementedness. Seneca said that, not me. Still, Bertrand, I’m worried. We need a team player for this one, not some go-it-alone eccentric.”

The Astronomer Royal smiled a thin, sour smile. “That, I fear, is a problem for our American cousins. After all, they wanted him. Indeed, they were very insistent.”

The Goddard Institute, New York

Outside the warm Kennedy terminal, a gust of icy air hurt Webb’s ears, watered his eyes and froze his ankles, and he found that the Royal Air Force had given him a suit transparent to wind. A man with a Cossack hat rode a strange, shaking machine which sucked up dark-streaked snow from the road and sprayed it at him. The morning sky was a menacing, dull grey. He headed for the airport bus but two men, warmly wrapped against the cold, emerged from the background and intercepted him. “Mister Fish? I am Agent Doyle of the FBI, and this is my colleague Agent O’Halloran. Forgive us if we don’t show our badges in a public place. Would you come this way, please?”

Webb settled into the back seat of a nondescript Buick with darkened windows. The car was deliciously warm. Agent O’Halloran took it silently over Brooklyn Bridge towards Central. Patches of crystal blue sky were beginning to show through the cloud. On Broadway, they continued north to the edge of Black Harlem. Good smells drifted from delicatessens and coffee shops. The snow was deep at the side of the road, and the breaths of pedestrians steamed in the bitter cold.

They stopped at the entrance to the Goddard Institute, an anonymous doorway with neither sign nor symbol to proclaim its NASA affiliation. Webb stepped out of the car. Across the street, rap music was blasting out of a stereo from a first-floor window. A phalanx of black children swooped down threateningly, but at the last second split and reconverged past him with marvellous precision. The stereo went off with a swipe, and the skateboarders swept off round the corner, ghettoblasters screeching. The limousine drove off.

“Mister Fish, good morning, we’ve been expecting you,” the stout, black guard at the desk said cheerfully. “First floor, elevator’s over there.”

On the first floor was a door with a sheet of paper saying “Do Not Enter” pinned on it. Webb knocked and a key turned. The room was bleak and almost unfurnished, apart from a green baize table strewn with notepads and water carafes. Four people sat around the table. The man who had opened the door, slimly built with close-cropped hair and light blue eyes, shook Webb’s hand. “Welcome to New York, Doctor Webb,” he said. “Have a seat and we’ll get on with it.”

Webb sat down and looked round the table. The smell of cigar smoke hung lightly in the air. Through it Webb thought he detected a sour odour which he could not place. Three of the faces he knew; the others were strangers.

Noordhof’s tone was informal but decisive. “First, gentlemen, a small organizational matter. This is a USAF project and as of now you are under my direction. The Europeans included, by consent of your respective governments. Does anyone object to this?” He looked round the table.

“Okay. Now we’re all here, let me make the introductions. Proceeding from my right, we have Herbert Sacheverell, from the Sorel Institute at Harvard.” A man of about forty, his red hair standing vertically on his scalp, thin, greasy-skinned and wearing a dirty black headband, nodded at the assembled group. “Doctor Sacheverell is our top asteroid man.” Jesus, Webb thought, America’s answer to Phippson: who put that loud-mouthed clown on the team? Sacheverell’s expression returned the compliment.

“Next to him we have Jim McNally, Director of NASA.” McNally, a slim, balding man of about fifty, dressed in a business suit with a slight, up-market shimmer to it, smiled and said Hi.

“The American contingent is completed by Wilhelm Shafer. What can you say about a hippie with one and a half Nobel Prizes?”

There was no need; a huge intelligence clearly lay behind Shafer’s restless grey eyes. He was, like McNally, about fifty; he wore a copper-coloured T-shirt decorated with a Buddha, and an elastic band held his long grey hair back in a ponytail. He grinned and nodded towards Leclerc and Webb. For Webb, the presence of the awesome Willy Shafer on the team underlined the gravity of the emergency as much as any lecture by the Astronomer Royal.

“On my left, let me introduce our two European partners. Oliver Webb, still catching his breath, is the British asteroid man. Next to him we have André Leclerc. André knows as much as anyone in the West about the space capabilities of the former Soviet bloc.” A tall, gaunt man, with a red bow tie and a black and white goatee beard, smiled and bowed to the centre of the table.

“And I’m Colonel Mark Noordhof. I know a thing or two about missile defence technology.”

“Who needs the Brits?” Sacheverell asked, staring at Webb with open hostility. “We have all the know-how we need in the States.”

“In part this is politics,” said Noordhof. “An attack on America is also an attack on NATO. If we get zapped on Monday the Russians could roll over Europe on Tuesday. But the essence is we need the best for this one.”

Sacheverell continued to glare, his eyes tiny through his thick spectacles. “Webb is a bad choice.”

Noordhof added: “And security. Sure, we’re up to our ears in civilian experts but what if they started dropping out of sight wholesale? We can’t treat this like the Manhattan Project. So, we’re using minimum numbers, drawn from a widely dispersed net. Small is beautiful is what the President wants. Kay, now let’s get down to it.”

Noordhof produced a cigar and played with the cellophane wrapping. He continued: “My brief comes from the President. I have to lead a team which will find the asteroid, estimate where and when it will impact if it does, estimate the impact damage, and determine whether it can be destroyed or diverted. I report directly to the SecDef, Nathan Bellarmine. He in turn informs the President, the DCI and the Joint Chiefs of our progress. The resources of these people are available to us and that’s some awesome resources. If you want the Sixth Fleet in Lake Michigan, ask and it shall be given unto thee.”

“Seek and we shall find,” said Shafer. “I hope.”

“Understand this,” said Noordhof. “This is not some cosy academic conference. This is a race, and the prize is survival. We have no precedent for this situation, no experience we can call on. We have to make up the rules as we go. Comments, anyone?”

“I’m not long out of bed,” Webb said. “How do we know that an asteroid has been diverted towards the States?”

“I’ll pass on that for now.”

“What are the political implications? Does it connect to the Red Army takeover?” Leclerc asked, speaking good Parisian English.

“That we don’t know.”

“We need a handle on the time element,” Sacheverell said. “It could be hours, weeks, months, years before the asteroid hits.”

A smoke ring emerged from Noordhof’s puckered lips. “We’ve been given five days to identify the asteroid and formulate an effective deflection strategy. This is Monday morning. Deadline is Friday midnight.”

Sacheverell laughed incredulously. “In the name of God…”

Noordhof continued. “And I’m authorized to say this. If at the end of five days we have failed to identify the asteroid, the White House will then formulate policy on the assumption that it will never be found before impact. I think it’s safe to assume that aforesaid policy will be highly aggressive.”

Shafer said quietly, “I think the Colonel is telling us that either we find the asteroid by midnight on Friday or the White House will retaliate with a nuclear strike.”

The room went still. Sacheverell paled, McNally flushed purple and Leclerc puffed out his cheeks. Noordhof leaned back and took a leisurely puff, whirls of blue smoke curling upwards. Webb felt suddenly nauseous.

“So we split the effort. Item One. Our masters want to know what will happen if the asteroid hits. Which one of you eggheads wants to take that one?” Noordhof looked round the table.

“I guess I’ll look into that,” said Sacheverell. “Sounds like a big computing job and we have the hardware at the Sorel.”

“Agreed?” Noordhof asked Webb, who nodded. The issue had already been raked over by experts; Sacheverell couldn’t do much harm channelled into that one.

“Item Two. Say we detect the asteroid on the way in. What can we do about it?”

“That’s a solved problem,” said McNally. “NASA looked into this on instructions from Congress some years back, when it was all a theoretical exercise. Anything we do will involve getting up there and zapping it.”

“Now hold on, zap it how?” Shafer asked sharply.

“With nukes, of course.” McNally looked bewildered.

“I’ve seen that stuff, and the Livermore Planet Defense Workshop, and the Air Force 2025 study. Theoretical’s the word. What do you think you’ll be zapping, Dr. McNally, shaving foam or a giant nickel-iron crystal? Hit it with nukes and you might wipe us out with a spray of boulders. We have to divert the thing without busting it up. How do you propose to do that without knowing its internal constitution?”

“It was only a suggestion,” McNally complained.

“Willy, Jim, liaise on the problem of how to handle the asteroid if we do find it. I’ll fix access to classified Lawrence Livermore reports as well as the public domain one. That leaves Item Three: where is this thing? Opinions, anyone?”

“I can draw up a list of candidates,” Webb said, still feeling queasy, “and get them checked out. We’ll need to use wide-angle telescopes.”

“Like the UK Schmidt?” suggested Sacheverell.

“They’ve mothballed it. We need Spaceguard and supernova patrol telescopes, say fast Hewitt cameras with CCDs. The Australians have one at Coona.”

“Colonel, this is an example of the security you can expect from these guys,” said Sacheverell. “Time on these machines is more precious than gold. You can’t just break into established observing programmes, not without people shouting like hell.”

“Ever heard of service time?”

“Cool it, gentlemen,” said Noordhof. “Wait until you see what we’ve laid on.”

Sacheverell said, “Whatever you’ve laid on, Colonel, our chances of identifying this rock in five days are practically zero. Especially with Webb guiding the search.”

“Jesus frigging Christ, don’t say things like that.” Noordhof stubbed out his cigar agitatedly.

Webb said, “What especially worries me is that these things are invisible most of the time. It could come at us from sunwards, in which case the first we’ll know about it is when it hits.”

Noordhof poured water from a carafe into a tumbler and took a sip, wetting his dry lips. Tense little wrinkles lined his face as he assimilated Webb’s information. He said, “Let’s name this beast.”

“I suggest Nemesis,” Sacheverell said. “After the Greek Goddess of Destruction.” There were nods of assent.

Noordhof said, “Nemesis. Good name. I have to tell you there is no chance of identifying it by conventional intelligence-gathering techniques. It’s down to us.”

“Many orbits will be unreachable by the Russian Federation even with their Energia boosters,” said Leclerc. “Perhaps Doctor Webb and I can co-operate.”

“I have programmes at Oxford which might help,” Webb said.

Noordhof nodded curtly. “You’ll have facilities to FTP them over. Now, gentlemen, we’re heading for Arizona. We have a Gulfstream waiting for us at LaGuardia. And from now on you free spirits are firmly corralled. No wandering the streets, no phone calls, no e-mails to colleagues. Lest you think this is paranoid, consider this. If the Russian leadership learn that we know about Nemesis, they can anticipate getting nuked in retaliation. So they’ll get their strike in first, to minimize damage to themselves.”

Shafer completed the logic: “Except that, since we know they’ll be thinking that way, we’ll have to get in first.”

Noordhof nodded again. “A careless word from anyone here could trigger a nuclear war.”

They stared at each other in fright. At last Webb recognized the sour odour. It was the smell of sweat, induced not by exertion but by fear. The chairs scuffled on the wooden floor as they stood up. “Strictly,” Webb said, “Nemesis is the Goddess of Righteous Anger. Have you people upset somebody?”

Southern Arizona

The desert air was cold, the sun was setting, and a bright red Pontiac Firebird, straight out of the nineteen-seventies, was waiting for them. It had fat tyres and a front grille like twin nostrils, and flames extended from the air intakes back along the bonnet and down the sides in a wonderful expression of psychedelic art from the period. The woman leaning on the car was about thirty, small, with shoulder-length, curly, natural blonde hair. She was wearing a slightly old-fashioned dress which didn’t disguise the fact of elegant bodywork underneath. She waved cheerfully at them.

Noordhof took the driving seat, Shafer sitting next to him. Webb added his holdall to a pile of luggage in the boot and squeezed into the back beside the blonde. She was diminutive against his strong six foot one frame. Leclerc sat on the other side of her and immediately delved into a sheaf of papers.

“Judy Whaler,” she said, shaking hands. “So you’re our European astronomer.”

“What’s your field, Doctor Whaler?”

“I’m a Sandian.”

“Is that a religious cult?”

She smiled tolerantly. “Sandia National Laboratories. The Advanced Concepts Group. We’re supposed to identify threats to national security and propose countermeasures.”

Noordhof said, over his shoulder, “The rest of the team’s on site.” He eased the car on to the road. Once on Speedway he opened the throttle and they moved throatily north on the broad street, past Mexican restaurants and cheap motels. It took about twenty minutes to cross the city and then they were clear, still heading north, and the grey Catalina Mountains were getting bigger. Paloverde cactus and little creosote bushes started at the roadside and stretched into the far distance. The sky was blue, but streaky clouds were beginning to form around the peaks, and above them was high cirrus. A four-engined jet was drawing a contrail.

In the confined space it soon became clear that Judy enjoyed bathing in cheap perfume. Her thigh was warm against Webb’s but he tried not to notice that — after all, she was a colleague. The road began to climb and twist and they passed over narrow bridges straddling deep canyons. Webb’s scrotum contracted, as it always did when he faced great heights or imminent danger. It would do a lot of contracting over the next few days.

Half an hour north of the city Shafer fell in impatiently behind a big, gleaming American truck with a vertical exhaust. The corrugated door at the back portrayed a leering, gluttonous child, with a frost-covered head, eating a Monster Headfreeze Bar. The road went steeply up the mountainside and the truck dropped gear noisily with a surge of exhaust smoke, labouring heavily. A second truck appeared on the skyline like a hostile Indian and bore down on them at alarming speed. Noordhof put his foot flat down and they sailed past with ease.

“Six point six litre V8,” Judy said, “delivering three three five bhp. The suspension’s too simple to cope with it.” The truck drivers blasted their air horns but the big Pontiac was already long past. At the top of the hill Noordhof slowed, and turned sharply off on to a stony, unpaved track. In seconds they had lost the highway and were heading steeply upwards, towards high mountains. Something momentarily glinted silver, on the summit of a high distant peak. The cactus gave way to a scattering of scrub oak and piñon pine.

After some minutes a cluster of timber houses appeared, straight out of the Wild West. A notice said Piñon Mesa, alt. 5500 ft. There were no signs of life.

“Survivalist community,” said Noordhof. “They’re armed to the teeth and they don’t like us. But you won’t be down here.”

The track ended at a wooden barred gate, and Noordhof kept the engine running as Webb fumbled with a padlock, feeling exposed. The buzz of a chainsaw came from the woods beyond, but he saw nothing through the trees. Then the real climb got under way, and the engine started to labour in earnest, and the air got colder, and Judy’s thigh got warmer, and the scrub oak gave way to juniper pine, and then the juniper gave way to big, heavy ponderosa. Through the trees Webb caught glimpses of the setting sun to the left, and tiny bugs crawling along a ribbon cutting through the desert. The Firebird’s suspension coped well with the potholes, but the heating didn’t seem to work.

Higher still, and the branches were covered with thin, freshly fallen snow, and they were following the tracks of some vehicle which had gone before.

They ran into cloud from below, and for the next fifteen minutes were enveloped in a light freezing mist, visibility about fifty yards, as the car continued to toil upwards. Finally the road began to level, the tops of buildings appeared over the trees and then the car was round a last hairpin bend and driving past the buildings into a paved car park at the side. Noordhof turned to them. “Eagle Peak. I’m told nobody ever comes here in the winter apart from astronomers and the odd black bear. But I still want you people sticking close to the Observatory. No wandering the hills.”

“Why haven’t you fenced it off, Colonel?” Shafer asked.

“Just in case some stray backpacker comes by. Guards and fences going up round a civilian building might draw attention. Our best protection is the semblance of normality.”

They climbed out, stiff, breaths misting. The air was fresh and pine-scented. Judy flapped her arms against her sides. To Webb, the combination of hairstyle and dress made her look like a resistance heroine from a World War Two movie. He stretched and walked round to the front, curious to explore his new surroundings. The snow was powdery underfoot and Shafer was having problems assembling a snowball. Noordhof piled their luggage out on to the tarmac.

A small, wiry man, with a neat grey beard, appeared at the front door. “Doctor Webb,” he said, stretching his hand. “Heard you in Versailles last year. Delighted to meet you at last. And I’ve read a fair number of your papers, of course. I feel as if I know you.” So this was Kenneth Kowalski. His Polish origins were obvious in his polite manner and his slightly clipped accent: second-generation American. Webb knew Kowalski’s reputation. Amongst observers, he was highly regarded, a careful stargazer who had transformed Eagle Peak from a dilapidated museum piece into a respected scientific tool. It didn’t have the world-class clout of Gemini at Cerro Pachon or the huge Keck ten-metre on Hawaii; but for rapid sky coverage, which is what the problem called for, it had these monsters licked. “We must talk about your work on the revised steady state theory after this is over. Of course you’re wrong. It’s an observed fact that the Universe is different at high redshift.”

Webb returned the grin and bowed. “All right-thinking people agree with you. So, this is the famous Eagle Peak Observatory?”

“You’re just at Base Camp,” Kowalski said. “The telescopes are much higher up.” He pointed to a squat grey building fifty yards away, and just visible in the mist. Through its windows Webb could see a small silver cable car. A thin cable stretched up from the roof of the building like a giant metal beanstalk, disappearing into the grey mist overhead. He looked at the tinny death trap apprehensively before realizing that, as a theoretician, he would have no reason to go up in it.

He smiled in relief and said, “Eagle Peak is a private benefaction?”

“Yes, it was a gift to the nation from the Preston dynasty in the thirties. It was modernized a few years ago with NSF funding. We were swarming with Air Force personnel yesterday, putting in extras for our visitors.”

Leclerc and Whaler joined them, and they made for the building. Sculpted in red sandstone over the outer door was a circularly coiled snake swallowing its own tail: the Pythagorean symbol of perfection and eternity. Inside, separating the atrium from the inner sanctum, was a double swing door made of glass framed in mahogany; each partition had the zodiacal signs engraved on it, six on each, in two columns. Through these doors and into the building proper, the warm air enveloped Webb like a hot bath towel. Kowalski led the way along a corridor lined with framed NASA photographs. Two doors led off to the left, and both were open.

The first of these revealed a large square kitchen with a long, cluttered farmhouse table. Then there was the common room, airy and spacious, with a panoramic window and a view of fog. In this room was a snooker table, and armchairs, and a bookcase full of paperbacks, and a coffee table with magazines and bowls of fresh fruit and sweets. Sacheverell and McNally were head to head in an animated discussion. As Judy passed the open door Sacheverell stopped in mid-conversation, adopted an angelic smile and said, “Well hi there,” and Webb hoped Nemesis would smash through the roof and turn Sacheverell into a red pulp.

The end of the corridor led into an open, glass-fronted area from which further doors led off. One led back into the common room. Kowalski pointed to a red door opposite it. “The nerve centre,” he said. “Later.”

Straight ahead of them was a flight of stairs, covered with a deep-piled blue carpet, so as not to disturb night observers sleeping by day. They went up these and found themselves in a long corridor. “The four rooms at the end are taken. If you like a desert view, take One or Two. If you like to look at mountains, take Seven or Eight.” The nearest door handle to Webb was attached to Number One and he took it. Leclerc took Number Two, while Judy Whaler presumably liked mountains and headed for Room Eight, directly opposite Webb’s.

The room had a log cabin feel to it and smelled of new pinewood although, again, a thick pile carpet covered the floor. A red, bloated sun was beginning to penetrate the fog.

Alone at last, Webb flopped on to the bed and tried to take stock:

(a) He’d been whisked off a remote Scottish mountain,

(b) told a tale of imminent Armageddon,

(c) transported to Iceland in a giant helicopter, in a blizzard,

(d) been flown over the roof of the world thence down almost to Mexico, and

(e) he was now on a remote mountain site surrounded by backwoodsmen.

(f) And he thought,

I don’t need this.

Money, Webb had learned soon after he joined the Institute, drove everything. Science was something you snatched in precious moments in between writing grant applications and publicity handouts. And in between meetings: the management loved meetings. The science, he had also learned, had to be Approved. The streetwise might aspire to soft carpets and executive desks, but the iconoclast stayed in an icy basement. The point of Buachaille Etive Mor had been to escape, get to work on real science. Webb wondered how they had found him, in that remote mountain setting.

What I do need is deep, dreamless, eight hours of sleep. He had a shower, washing away the camping and travel, and wrapped himself in a large white towel. The beautiful, climactic moment came when he approached the bed, weary muscles tingling in anticipation of flopping down on it. He savoured the moment, he flopped, and there was a sharp knock on the door.

Noordhof was in Command Mode. “The cable car. Five minutes. Observing suits in the dormitory cupboard.”

You’re in the army now, Webb thought.

The tiny silver cable car barely took four people and had the feel of something cobbled together by an enthusiast with a Meccano set. Noordhof, Sacheverell and Webb squeezed in, dressed like Eskimos, with Sacheverell taking up three quarters of Webb’s bench. A notice said

Kowalski marched over to a control panel, pressed a red button and pulled a lever. On the panel, a row of lights flashed on. There was a clash of engaging gears, a loud whining, and a large metal wheel started to turn. He trotted swiftly to the car and climbed in next to Webb, pulling the door shut just as the cable took up the slack and the car started to move. “It’s quite safe,” he said. “If you work it by yourself just remember to get in quickly.”

From about fifty yards up, the ground faded into the mist and they lost nearly all sense of motion; they were sitting in a gently swaying cable car, immersed in a co-moving grey bubble. After some minutes they cleared the mist. Far above, almost over their heads, was a pinnacle of rock, still in sunlight. On its summit Webb could barely make out a building. Near-vertical rock faces fell away from it in every direction; lines of ice filled the ridges and angles. Webb looked up at the dizzying height and thought Why not? What more can they throw at me? Below them, the receding cloud turned out to be fairly localized, and they could see the track they had taken in the Firebird, twisting through the forest. Beyond it, the desert was now dark.

Webb assumed that his hypothetical Meccano enthusiast had known all about wind-pumped resonances, and metal fatigue, and the tensile strength of tired old steel. He was delighted to see that Sacheverell was even more terrified than him. There was sweat on the man’s brow and his eyes were staring. He produced a handkerchief and wiped his face with it. Mischievously, Webb turned the screw a little. Trying to sound casual, he asked Kowalski: “Ever been an accident with this?”

Kowalski looked at him curiously and glanced quickly at Sacheverell. Then he nodded solemnly. “Once.”

The car began to sway, a long, slow oscillation as the cable vibrated like a bowstring. After some minutes the vibration died and the car’s upward climb slowed; the machinery seemed to be struggling. Only a few yards away was an icy, vertical rock face; the car was being hauled almost vertically up its cable. Sacheverell giggled, but it was a bit high-pitched. The car edged up and slotted into a gap in a concrete platform projecting into space. They piled out. There was a gap of nine inches between car and platform, and about three thousand feet of air below the gap.

Eagle Peak was a spacious natural platform, about a hundred yards by eighty. Its perimeter was marked out by a stone wall about four feet high. There were two observatory domes, copper-coloured in the light of the sinking desert sun. One small, no more than fifteen feet in diameter; it was dwarfed by its companion, about a hundred feet across. The air was wonderfully clear, and bitterly cold.

Kowalski took them into the little dome. He picked up a metal handset from mobile steps and pressed a button. The dome was filled with the noise of machinery as the shutter opened. Temporarily Webb had the illusion, familiar to an astronomer, of standing on a rotating platform underneath a static dome. Kowalski rotated the dome until the sinking sun streamed into the open slot. In the centre of the circular building stood a circular metal platform about three feet tall and six wide. The top of the platform was clearly built to rotate, and two stanchions rose from it, supporting between them what looked like a big dustbin about three feet in diameter and six feet long.

“The supernova patrol telescope,” Kowalski said with, Webb thought, a touch of pride. “With an altazimuth mounting,” he added, mentioning the obvious, “to save weight. This is a fast survey instrument and it needs to travel light. For supernova searches we’re just measuring the apparent magnitudes of galaxies, looking for any change which might indicate a stellar explosion. Speed is the priority and we don’t need long exposures.”

Webb asked, “How faint do you go?”

“Magnitude twenty-one in ten seconds, over a one-degree field. The instrument has a pointing accuracy of one arc second. We no longer need equatorial mountings now that we can use computers to update the altitude and azimuth of the target star. The slew rate, galaxy to galaxy, is less than a second. It is probably the best supernova hunter in the business.”

It was an impressive instrument.

Sacheverell tittered. “Forgive me, Doctor Kowalski, but it has as much chance of finding Nemesis in six days as I have of winning the lottery.”

“Will you cut out talk like that,” Noordhof said.

Kowalski smiled politely and said, “Now let me show you the other telescope.”

They made for the monster dome. By now the sun was down and Kowalski switched on the light to reveal a telescope about sixty feet tall, on a classical equatorial mounting. He led them up metal stairs to a circular balcony. They spread themselves around the balcony and looked across at the giant, battleship-grey instrument. A metal plaque said “Grubb Parsons 1928”; it had been shipped over from the UK or Ireland at some stage. Mounted piggy-back on the main frame was a secondary telescope, and next to it a mobile platform, with a guard rail, which would raise and lower the observer depending on where the big telescope was pointing in the sky. Attached to the bottom of the telescope, at the location of the eyepiece, was a metal box about four feet on each side, from which cables trailed across the metal floor to a bank of monitors clear of the instrument. At the prime focus of the telescope, far above their heads, was a cylindrical cage. The cage contained the secondary mirror. It also came with a chair and harness; the observer had to supply the steel nerves.

It was twenties technology, a masterpiece of precision and power, updated for the new millennium with cutting edge instrumentation. As a tool for discovering Nemesis, Webb would without hesitation have gone for a pair of binoculars.

“This is of course the ninety-four-inch reflector,” Kowalski said. “As you see we have set up a spectrograph at the prime focus. The atmospheric seeing at this site is excellent. In good conditions it can be sub-arcsecond, and I’ve even seen it diffraction-limited.”

“I hope you don’t expect to find Nemesis with this,” Sacheverell said in a tone of incredulity.

Webb said, “The Grubb Parsons will be very useful if we do find Nemesis. We can use it for astrometric backup to get a high-precision orbit, and we’ll need it to get a spectrum.”

“What do you want a spectrum for?” Noordhof asked.

“Nickel iron or shaving foam, Colonel? We’d be able to work out the surface mineralogy which might be vital in formulating a deflection strategy. However, first catch your hare.”

Noordhof gave Webb a look. “That’s what you’re here for, Mister.”

Kowalski said, “The Grubb can only be operated from up here. If you want broadband spectrophotometry you have to change the optical filters, which means you have to go into the cage. But we can control the supernova patrol telescope from down below. It can sweep the whole sky to magnitude twenty-one in a month.”

Sacheverell’s head shook inside his fur cape. “It’s not nearly good enough. Nemesis is a moving target.”

By now the desert was black; the sky was dark blue and stars were beginning to appear, unwinking in the steady air. Far below, Base Camp was a tiny oasis of light in the dark. The little car swayed in space as Sacheverell, Webb and Noordhof squeezed in. The cable car lurched and Kowalski ran out of the wheelhouse, jumping in just as the car launched itself into space. He pulled the door shut with a tinny Clang! and in a second they were sinking fast.

Sacheverell was looking at the dark cliff drifting past a few yards away. His breath misted in the freezing air. In a tone of exaggerated casualness, he asked: “About this accident. What happened?”

“It was a lightning strike. The car stopped half-way down with one of our technicians in it, and it was three days before anyone noticed. This was last winter.”

“He survived?”

“Heavens no. We had to thaw the corpse out on a kitchen chair before we could get it in a body bag. You should have heard him cracking.”

A look of pure horror came over Sacheverell’s face, and Kowalski grinned. He’d had his revenge.

Eagle Peak, 24^h00, Monday

The red door was solid and heavy — or maybe, Webb thought, he was just feeling fragile. It had a small brass label marked “Conference Room.”

The conference room was brightly lit, like a stage, and measured about twenty feet by twenty. There was a heavy dark blue curtain on the left, a long blackboard on the right, and an old-fashioned circular clock, looking like railway station surplus, on the wall straight ahead. Its hands showed three minutes past midnight. Otherwise every foot of wall in the nerve centre was taken up with desks, computer terminals, printers, scanners and deep bookshelves stuffed with scientific journals, books and gleaming brass instruments from an earlier era.

The centre of the room was taken up with a long pine table, already scattered with papers. There were deep leather armchairs scattered around, their dark blue matching the curtain, and working chairs around the big table, and seven colleagues on these chairs awaiting Webb’s dramatic entrance, and vertical, disapproving wrinkles above Noordhof’s lips. “Webb, you’re three minutes late. I’ll say it again: this isn’t some cosy academic conference. If Nemesis is coming in at twenty miles a second, you’ve just cost us three thousand, six hundred miles of trajectory. Half the diameter of the Earth. The difference between a hit and a miss.”

Webb flopped down at the end of the table. “I’m feeling a bit fragile.” The soldier shot Webb a venomous look and then turned to Sacheverell. “Let’s get into this. Herb, what’s the state of play in the hazard detection arena?”

Sacheverell leaned back in his chair. “As you’d expect, the big players are the Americans. We have two main civilian programmes, one in New Mexico, and one right here in Arizona. Lowell Observatory have a point six-metre Schmidt at Flagstaff, just a few mountains to the north of us, and the University of Arizona have Spacewatch Two on Kitt Peak, to the south. And the University of Hawaii are just starting a massive programme on Maui, one of the Hawaiian Islands. It’s a sixty-million-buck project, financed by the USAF.”

“Is that it?” Noordhof asked.

“There are photographic programmes but if you don’t have a CCD you’re not in the game. Put a charge-coupled device at the eyepiece of your telescope and you’ll get as much light in two minutes as you would with a two-hour exposure hour on a Kodak plate. In that two minutes Flagstaff can cover ten square degrees of sky down to magnitude twenty. Spacewatch Two covers only one square degree, but it gets down to twenty-one in half the time.”

“Sacheverell has overlooked the rest of the world,” Webb pointed out. “For example, the Japanese have a private network of amateurs and they’ve also started with a pair of one-metre class telescopes. The Italians have a small-scale network centred round their instruments in Campo Impera-tore, Asiago and Catania. The French and Germans have a one-metre Schmidt on the Côte d’Azur.”

Sacheverell waved his hand dismissively. “I don’t want the survival of America to depend on a bunch of Japanese amateurs. As for the Italians, they’re penniless. Half the time their telescopes are lying idle. We’re detecting three Earth-crossers a night.”

Kowalski said, “And we have our upstairs telescopes. We operate our Schmidt remotely, as a robotic telescope, from this room. Normally we feed in a pre-selected list of galaxies over there but we could just as easily scan the sky looking for a moving object.”

Noordhof tapped the table. “Like I said in New York, you people have every conceivable facility at your disposal.”

“You mean Pan-STARRS?” McNally asked, round-eyed. “The Hawaiian system?”

“Ay-firmative. With immediate effect, it’s yours.”

“What are their CCD chips in these systems like?” Webb asked.

Sacheverell waved sheets of paper. “While our token Brit is feeling fragile I’m downloading from Albuquerque, with the Colonel’s help. They’re large format, high quantum efficiency, fast readout. They perform close to the theoretical limit.”

Shafer was scribbling furiously on a yellow notepad. He had dispensed with his ponytail and his long grey hair was swept down over his shoulders. “What’s the sky coverage with these Pan-STARRS telescopes?”

Sacheverell said, “Nine square degree starfields, reaching mag twenty with twenty-second exposures. They don’t go as faint as Spacewatch Two but like I say their CCDs have fast readout. They can carry out a saturation search in half the time of Spacewatch. Spacewatch has depth; Albuquerque has breadth.”

Webb said, “I’m impressed. Herb, impress me even more. Tell us what you’ve got in the southern hemisphere.”

Sacheverell hesitated. “Okay, we’re weak there.”

“What’s your point, Oliver?” Noordhof asked.

“We have almost no coverage of the southern sky. Nemesis could sneak up on us from south of the celestial equator when all our telescopes are scanning the sky to the north. Maui can look south to a limited extent, and the ESO Schmidt in Chile might have picked it up serendipitously if they hadn’t shut it down.”

“The British closed down the UK Schmidt in Coonabarabran,” Sacheverell accused Webb, pointing a skinny finger in his direction. “Why did you guys leave yourselves with no asteroid-hunting capability?”

“The giggle factor. Our Minister for Science thought the impact hazard was a joke.”

“Are you telling me half the sky is uncovered?” Noordhof asked in dismay.

“It’s worse than that. I’m thinking of the Atens.”

“Excuse me?”

“I hate to add to our troubles, but there’s a blind spot about thirty degrees radius around the sun. Anything could be orbiting inside it. An Aten is an asteroid with an orbit which puts it inside the Earth’s orbit, and therefore in the blind spot, most of the time. Only a handful have been discovered but nobody knows how many there really are. Now say the Russians discovered one on a near-Earth orbit.”

Noordhof acquired a thoughtful look. Leclerc had been writing in a little red leather Filofax. He looked up and said, “The probability that we would independently discover it is remote. It would hide in sunlight until it pounced. An Aten makes a lot of sense as a weapon.”

Webb continued, “Sacheverell’s telescopes are all geared up to search the sky around opposition. They’re pointing high in the night sky, far from the sun. But if an Aten is coming at us, it won’t be there. It will come at us low in the sky, close to the sun. Most of Herb’s telescopes can’t even reach that low. If Nemesis is an Aten you might see it before dawn, or just after dusk, a few days before impact. Binoculars would do.”

Noordhof took a cigar from his top pocket. “I need a consensus on the detection issue. Can you people deliver or not?”

Shafer had finished his scribbling. Now he stood up and moved over to the blackboard. He picked up yellow chalk and started to write in a fast, practised scrawl. “The way these telescopes are operated, sure there’s a strong selection effect acting against the discovery of Atens. But I disagree with Ollie about Atens as weapons. For precision work the Russians would need something they could track for a long time, maybe years, and you can’t do that with The Invisible Asteroid. I say Nemesis is reachable with Spacewatch and Pan-STARRS. There are 4π steradians of sky and each steradian is 180/π degrees on a side. That gives us forty-three thousand square degrees of sky over the whole celestial sphere. How much of that can we cover? For a start these things are faint, which means we have to go deep. But we can only do that in a pitch black sky. Okay, so there’s no moon this week. But to avoid twilight the sun has to be at least twelve degrees below the horizon, and to avoid atmospheric absorption the sky we’re searching has to be at least thirty degrees above it. I reckon we have maybe only five or six thousand searchable square degrees of sky on any one night.”

“Declining to zero if it’s cloudy,” Judy Whaler pointed out.

“The five-day local forecast is good,” Kowalski said. “Except for the last day.”

Shafer continued: “Okay, from Herb’s figures I reckon the whole of the world’s asteroid-hunting telescopes will cover no more than two or three hundred square degrees of sky an hour. That means say a month to cover the whole sky once.”

“And we’ve been given five days,” said Whaler. “Six to one against.”

“Not even remotely,” Shafer disagreed. “Look at square A on Monday, and by Murphy’s Law Nemesis is in square B. Look in B on Tuesday and it’s moved to A or C. Apart from which, most of the time it will be too faint to be seen, because it will be too far away, or hidden in sunlight like Ollie’s Atens, or camouflaged against the Milky Way.”

“So how long, Shafer?” Noordhof asked impatiently.

Shafer drew a graph. He measured off tick marks on the axes and labelled the horizontal one “diameter in km,” and the vertical one, “p % per decade.” Then he drew an S-shaped curve, copying carefully from his paper. Webb saw what the physicist had been calculating and was awestruck at the speed with which he had done it. Shafer tapped at the blackboard. “Assume Nemesis is a kilometre across, with the reflectivity of charcoal. That gives it absolute magnitude eighteen at one AU from Earth and sun.” He drew a vertical line up from the 1-km tick mark on the x-axis to its point of intersection with the curve, and then moved horizontally across to the vertical axis, where he read off 0.85. “You want to discover Nemesis with eighty or ninety per cent probability, with all the world’s asteroid telescopes going flat out? Assuming it’s not an Aten? It will take us ten years.”

“We have five days,” Noordhof reminded Shafer in a flat tone.

“So consult a psychic,” said Shafer, going back to his chair.

The tense silence that followed was broken by the loud crackling of cellophane as Noordhof unwrapped his cigar.

“Willy, I think your calculation is flawed,” Webb said, knowing this was a rash thing to say to the mighty Shafer. “If it’s coming at us in a straight line out of a dark sky then it’s already close and bright. We don’t have to spend ten years looking.”

The physicist gave Webb a disconcertingly hard look. “Ollie, if it’s close and bright and coming at us in a straight line out of a dark sky, we’re about to be history.”

“It’s our only chance to find it.”

Sacheverell shook his head sadly. “It must be the jet lag. Willy has just told us that by the time it’s close enough to be found it’s too late to be stopped.”

“We can harden up on this.” Webb crossed to an empty bit of blackboard. “Say Nemesis is going to hit us in thirty days. There are 86,400 seconds in one day. If it’s coming in at fifteen kilometres a second then it’s only 30 × 86,400 × 15 = 39 million kilometres away now, a quarter of an AU, which makes it sixteen times brighter than it was at one AU. Herb, what’s the brightness of a one-kilometre asteroid at one AU?”

“Eighteen for a carbonaceous surface. Everybody knows that.”

Shafer was tapping at a pocket calculator. He said, “Inverse square brightness, forget phase angles. Yes, if Nemesis is a month from impact it could have magnitude fifteen. We should be able to pick it up now.”

Webb said, “Go for sixteen or seventeen visual and we cut the exposure times to seconds. We might even have a continuous scan. We could cover the sky in a week. It’s then down to bad luck, like coming at us out of the sun or approaching from the south.”

McNally’s slim fingers were agitatedly drumming on the table. “Can we inject some realism into this? If we’re a month from impact what am I supposed to do about it? Call up Superman? I need a year minimum, preferably two or three, to build some hardware.”

“But if Nemesis is a year from impact now, we’ll still only detect it in eleven months’ time, when it’s on the way in. A last-minute deflection is the only scenario you can work on.”

“Let me understand this,” Noordhof said. “If you guys are right, the chances are hundreds to one against our finding this thing in the next five days. Unless it’s so close that it’s maybe a month or two from impact. And even then maybe not if it’s coming at us out of the sun.”

There was a silent consensus around the table.

“Shit,” Noordhof added, looking worried. He turned to the Director of NASA. “McNally, you have to come up with a deflection strategy based on the month-from-impact scenario.”

“For Christ’s sake, that’s just off the wall.” The NASA director’s face was flushed.

Firmly: “You have no choice in the matter.” Noordhof was playing nervously with his unlit cigar. Webb had a momentary vision of Captain Queeg rolling little metal balls in his hand.

“Jim,” Shafer’s tone was conciliatory. “We’re the A team. Maybe you and I can come up with something.”

McNally shook his head angrily.

Leclerc asked, to break the tension, “What would happen if say somebody in Japan found an asteroid?”

“The whole astronomical community would know it within hours,” Sacheverell said. “Civilian discoveries go straight to the Minor Planet Center which has electronic distribution to all the major observatories. But look, forget Japan, Europe and Atens and crap like that. The action is at Lowell, Spacewatch and Hawaii”—Kowalski winced slightly, but said nothing—“and we’re linked in to these places here. We’ll see the exposures build up in real time.”

Webb said, “Detection isn’t enough. If we don’t follow it up, we lose it. We have to track it long enough to get a reliable orbit.”

Sacheverell said, “Follow-up means we come back to it every few hours, using the interval in between to search for other asteroids. An interval of a few hours gives you its drift against the stars enough to pick it up again the following night. To get a believable orbit, you need to track it for at least a week. To get decent precision, say to launch a probe at it, you have to update over months. There are follow-up telescopes in British Columbia, Oak Ridge Massachusetts and the Czech Republic. Also at Maui.”

Kowalski nodded. “We’re well placed for follow-up here. Our Grubb Parsons has a long focal length and its point spread function is small. On a good night we can do very high-precision astrometry.”

“The Grubb Parsons is vital,” Webb agreed. “Without it follow-up would double the load on the discovery telescopes.”

Leclerc, pen hovering over his Filofax, asked again: “Suppose you find an asteroid and follow it up. What then?”

Webb said, “Nearly every one we find will be harmless. We’re looking for a needle in a field of haystacks. Old Spacewatch could pick up six hundred moving objects on a clear winter’s night, and overall twenty-five thousand asteroids a year. Out of all that, fewer than twenty-five were Earth-crossers. The rest were main belt. Now with all the new systems combined the detection rates are fifty times higher. But that means we have also fifty times more junk to be sifted through. With the CCD mosaics you people are talking about I reckon we need to interrogate about a billion pixels every ten seconds. We have nothing like enough computing power on site to handle the data.”

Noordhof attempted a smile. “We have the Intel Teraflop at Sandia. It makes your hair stand on end. That too is yours, a personal gift from a grateful nation.”

Judy said, “That’s Wow, but how do we transfer the data over? Ordinary cable transmission can’t handle the flow.”

“We have satellites that will.”

“In that case,” she replied, “problem solved. I’ll download the CCD processing software from Spacewatch and transfer it over to our magic machine.”

“We have orbit calculation packages at the Sorel,” Sacheverell said. “I’ll pull them over to your computers. I presume it’s all Unix-based?”

Noordhof nodded. “All communication between here and Albuquerque must be secure. I’ll get a key encryption package installed when I’m fixing access to our computers. Judy, work at it through the night. Let’s be operational by dark tomorrow. Herb, when can you give me a damage profile for Nemesis?”

“Two or three days, if I can access the Sorel.”

“Have you been listening, Herb? At that rate we might as well wait for the field trial. I want a report over breakfast. O seven hundred sharp, all present, and nobody feeling fragile.”

Webb said, “We’re doing this all wrong.”

Shafer said, “Oliver, I was joking about a psychic.”

Eagle Peak, Tuesday Morning

The smell of scrambled eggs and coffee drifted into Webb’s room, and sunlight had found weak spots in the heavy curtains’ defences. He reached for his watch with an arm made of lead, focused on the little hands, and knew he was in for another of Noordhof’s special looks. He rolled on to his stomach and looked longingly at the laptop computer and the crumpled sheets of paper scattered over the floor, which had shared his journey from Glen Etive. But there was no time. He skipped shaving and made it with minus two minutes to spare.

Breakfast things were laid out on the kitchen table and Shafer was dithering around the microwave oven. Judy was in an easy chair; she was into a severe white blouse and black skirt, a plate on her lap, and she was using her sharp, red-painted nails to carefully peel a hard-boiled egg. Sacheverell sat next to her with a plate on his lap. He was also pouring her a coffee and she flashed him a smile. McNally, Leclerc and Kowalski were at the window, sipping coffee and looking out over an expanse of desert from which the occasional tree-covered mountain protruded like an island in the sea.

Noordhof was busy on a croissant. A row of cigars protruded from a shirt pocket. He made a show of looking at his watch as Webb entered.

Webb poured himself coffee from a big percolator, heaped a plate with sausage and scrambled egg, and settled down at the farmhouse table. “You’re giving me a hard stare, Colonel.”

“Please God, deliver this man unto my sergeant,” Noordhof prayed.

A screen on a tripod had been set up and an overhead projector on the end of the kitchen table was throwing white light at it. The soldier nodded to Sacheverell, who had a stubble and looked a bit ragged.

Sacheverell put fork and plate aside, wiped his fingers with a handkerchief, took a pile of transparent overlays to the projector and moved them on and off the machine as he spoke. The first one showed three teddy bears of different sizes, with bubble text coming from the mouth of each, like a comic. One bear was saying 10⁴ Mt, another 10⁵ Mt and the third 10⁶ Mt. “I examined three scenarios which straddle the likely energy range. I’m calling them Baby Bear, Mummy Bear and Daddy Bear. As you see Baby Bear is ten thousand megatons, Mummy Bear a hundred thousand and Big Daddy is a million.

“First I had a look at Baby Bear, deep ocean impact. I had the idea that maybe the aggressors — the Russians? — might want to take out the UK or Japan while they were about it. Anyway, the Atlantic and the Pacific are big, easy targets. Okay. So half a minute into impact we have a ring of water three or four hundred metres high. Wave amplitude falls as it moves out but you’re still looking at a fifteen-metre wave a thousand kilometres from the impact site.”

“In the open sea?” Shafer asked.

“In the open sea. Tsunamis are long-range, because the ocean is a surface and specific energy drops linearly with distance rather than inverse square. An earthquake in Chile in 1960 created ocean waves which travelled over ten thousand miles and killed a lot of people in Japan.”

“What was its wave height?” McNally asked, coming back from the window.

“In the open sea, twenty centimetres. The wavelength is hundreds of kilometres.”

“An eight-inch wave killed people?” McNally asked, bewildered.

Sacheverell winced. “No. When the wave runs into shallow water the same amount of energy is being carried by less and less water. So when it approaches a shoreline it rears up. The twenty-centimetre wave became a metre or two high. Killed a couple of hundred people, if you count the ones that just went missing.”

“So what’s the run-up factor on your fifteen-metre wave, Herb?” Shafer asked.

“Ten to forty, depending on the shoreline. If we say twenty, the wave is three hundred metres high when it hits land, assuming the impact was a thousand kilometres offshore.”

“The height of the Eiffel Tower,” Leclerc said. “How far inland would a wave like that travel?”

“Again it depends. Topography, roughness of surface. Flat agricultural land would flood for ten or twenty kilometres inland. When I say flood, I mean the wave is still two hundred metres high maybe five kilometres inshore.”

Webb said: “An Atlantic splash of that order would take out nearly all the major cities in Britain.” Although he was actually trying to visualize a half-mile tsunami roaring up Glen Etive.

“I don’t believe these figures,” Shafer said, without bothering to explain why.

“Europe is protected by a steep continental shelf,” Sacheverell informed Webb. “It reflects about three quarters of the energy back into the ocean.”

“Great,” Webb said. “Really great. Now I know that when I turn into Piccadilly the wave coming at me is only a hundred metres high.”

Noordhof went to the percolator and came back with a refill. “And if Baby Bear hits land?”

“Blast, heat and earthquake. The blast is a pressure pulse followed by a hot wind. The nuclear weapons people use an overpressure of four psi to define total devastation although there’s huge loss of life even at two, mainly from blizzards of flying glass in urban areas. Hit L. A. and you’ll blow the roofs off houses in San Diego. A Baby Bear on Philadelphia would rip people up from Baltimore in the south to New York in the north.”

“You could take out England from London to Newcastle,” Webb interrupted, still doing his patriotic bit.

“Who would want to zap your feeble little island?” Sacheverell asked. “I’ve taken the threshold for fire ignition to be about a kilowatt applied to a square inch for a second. It turns out you ignite everything in sight — tyres, grass, everything flammable. A hundred miles away, it’s like standing four inches from an electric fire for ninety seconds.”

“That must depend on whether the asteroid hits the ground or breaks up in the air,” said McNally.

“No. The heat comes from the hot wake trailing the fireball. Lastly, earthquake. I’ve taken Gutenberg-Richter Nine as defining total devastation, and I’ve assumed five per cent of the kinetic energy goes into shaking the ground. We’re looking at Nine over a region about a thousand kilometres across.”

Noordhof took a sip at his coffee. “So Baby Bear takes out a few cities or floods one of our seaboards. But it doesn’t totally destroy the USA and it leaves our nuclear potential intact. So let’s turn the screw a bit. Herb, take us to Mummy.”

“Wave height scales as the square root of the impact energy, and the flood plane extends as the four thirds power of the run-up wave. These are approximations. They’re beginning to crumble when you get to the really big numbers. Mummy Bear makes an open ocean wave fifty metres high a thousand kilometres away. The run-up factor stays the same so you hit the coast with a wave a kilometre or two high. I guess the Rockies or Appalachians would protect the central USA. For an Atlantic impact, I don’t know how much of Europe would be left.”

Shafer said: “That’s just movie stuff. A wave that big would break up. The tsunami would only take out a few million people.”

Noordhof interrupted: “Our Kansas silos stay intact.”

Shafer said, “But you’re not expected to shoot back. This is just a great natural disaster, right?”

“And a land impact? Blast, heat, earthquake?” Noordhof’s voice had an edge to it.

“Ten times the impact energy gives you ten times everything else. And a sixteen-mile crater as a bonus.”

“I don’t like the sound of that,” Noordhof said. “You want to tell us about Big Daddy?”

“Give me an extra power of ten and I’ll shower the States with ballistic ejecta. At the impact site, everything as far as the horizon vaporizes. It gets thrown above the atmosphere, recondenses as sub-millimetre particles at a thousand degrees and falls back over an area equal to the USA. Allowing for heat lost to space etcetera I find that the thermal radiation at the surface is about ten kilowatts per square metre for an hour or more after impact. It’s like being inside a domestic oven. Try to breathe and your lungs fry. The whole of the United States turns into one big firestorm. I guess nothing would survive.”

Sacheverell tidied up his papers to show he was finished. There was a thoughtful silence. Webb broke it by saying, “These computations all have big uncertainties. My reading is you’d have less earthquake and more heat. You’d burn the States even with Mummy Bear. Partly I’m thinking of the Shoemaker-Levy 9 comet fragments which hit Jupiter in 1994. We had a coherent stream of material which gave us twenty impacts on to the planet. The heat flashes from the fallback of ejecta were a hundred times brighter than those from the fireballs themselves.”

Shafer stirred his coffee. “Big Daddy is good news.” There was an astonished silence. Noordhof’s cup stayed poised at his lips.

Webb nodded. “I believe so, Willy. There are maybe a couple of a million cometary asteroids out there, any one of which could give us a hydrogen-bomb sized impact. They probably happen every century or two. This century we had Tunguska in the Central Siberian Plateau on June 30th 1908. It came in low from the sun at about 7:15 a.m. That was ten to thirty megatons. Hundred megatonners come in every few centuries. They’ve been recorded as celestial myths in Hesiod’s Theogony and the like. If you go to a few thousand megatons, you’re probably into the Bronze Age destructions: the climate downturn, Shaeffer’s mysterious earthquakes in the Near East.”

“What has this guy been smoking?” Sacheverell asked.

“Do you accept your own impact rates? The ones you keep re-publishing?”

“What of it?”

“With a decent chance of a thousand megatonner in the last five thousand years?”

“Sure,” Sacheverell sneered. “Probably at the north pole.”

“So we had ten megatons in Siberia in 1908, a megaton in the Amazon in 1930, another few megs in British Guyana in 1935, but the five thousand years of civilisation before that were missile-free? And what about Courty’s Syrian excavations showing Bronze Age city destructions caused by blast? And when Revelation talks about a great red dragon in the sky throwing a burning mountain to earth, and the sun and moon darkened by smoke, and the earth ablaze with falling hail and fire, and a smoking abyss, and the same celestial dragon keeps appearing throughout the Near East, in Hesiod in 800 BC, Babylon in 1400 BC and so on, and Zoroaster predicts a comet crashing to Earth and causing huge destruction, this is all poetic invention, drawn from a vacuum, based on no experience? You are aware, Herb, that comets were described as dragons in the past? That a great comet has a red tail? You have actually heard of Encke’s Comet and the Taurid Complex?”

Sacheverell’s face was a picture of incredulity. “I can’t believe I’m hearing this. You are seriously telling us that responsible policymaking should be based on a Velikovskian interpretation of history? You want to throw in the Biblical Flood? Maybe von Däniken and flying saucers?”

“This is breathtaking,” Webb said. “We’re dealing with a threat to hundreds of millions of lives, and you think you can responsibly ignore evidence of past catastrophe just because you don’t have the balls to handle it?”

Sacheverell stabbed a thin finger. His voice was strident and the eyes behind the thick spectacles were angry. “You want to identify gods with comets and combat myths with impacts? What sort of a scientist do you call yourself? I say you’re a charlatan.”

“That’s it, Herb, go with the flow like a good little party hack. I say stuff your cultural hang-ups and your intellectual cowardice.”

Judy had frozen, mouth wide open to receive a hardboiled egg. Shafer was grinning hugely. Noordhof, his face taut with anger, punched a fist on the table. “Enough! Now get this. I could spend hours listening to you guys at each other’s throats. Unfortunately we don’t have hours to spend. Now simmer down. Ollie, get to the point. Explain to those of us down here on Earth why Big Daddy is good news.”

Sacheverell sat down heavily, flushed and rattled. Webb said, “Because we could spend two or three thousand years looking for Herb’s Little Bears. Because we have a better chance of detecting Big Daddies further out. And because we can maybe hit a big one harder without breaking it into a swarm.”

Shafer brushed his grey hair back from his shoulders with both hands. “And because the actuarial odds are that we’ve been hit by a few Tunguskas and maybe even a Baby Bear or two in the historical past, but civilization survived. The damage is relatively local. If you want to utterly destroy America, you have to go for bodies between half a kilometre and two kilometres across. Too little, and you leave the surviving States with lots of muscle and fighting mad.”

“You guys are wrong,” McNally said. “We’re only fighting mad if we know the impact was an act of war. And like Herb said, we’re not supposed to know that. Look, even with the Baby Bear scenario you have an America with half its population wiped out, its industrial base gone, no political infrastructure, probably just chaos and anarchy. This is a gun society. We’d destroy ourselves, finish the job the Russians started. Zhirinovsky could do what he liked, where he liked and we’d be too busy to care.”

Shafer said, “Jim, you just want a Baby Bear because it’s easy to shift.”

Noordhof lowered his head pensively. Then he said, “I go with McNally. The uncertainties are too large for confident statements about the political intentions of the enemy, whether to incapacitate us or utterly destroy us. We conduct the scope of our search to encompass the full range from Baby Bear to Big Daddy.”

“Forgive me, but that is utterly impractical,” said Kowalski. “If you want to go down to ten thousand megatons you have to reach extremely faint limiting magnitudes. Which means very long exposures even with quantum-limited CCDs. You could wait a hundred years, as Oliver says. Upstairs, in zero moonlight, we can only go to magnitude twenty-two visual at solar elongations more than seventy-five degrees.”

Shafer said, “If you’re drunk and you lose your keys you look under the street lamp. Not because they’re necessarily there, but because that’s where you have the best chance of finding them. Meaning, we go for what’s practical. Extremely faint magnitudes take too long.”

Webb piled on the pressure. “You’re wrong on this one, Mark. The important thing is to cover the whole sky as fast as possible, and keep covering it until Nemesis swims into the field of view. Let’s just hope Nemesis is a big one. That way we have a chance of finding it while it’s still far out. And we get maybe months of warning. I say we aim for full sky coverage in a week. We should go for ten-second exposures on Kenneth’s supernova hunter, limiting magnitude seventeen.”

Noordhof looked at Sacheverell, who nodded reluctant agreement. The soldier said, “Okay I guess I’ve been flamed. Forget the Baby Bears. For now.”

Shafer asked, “Can you fix Pan-STARRS for us, Colonel? Give instructions for a magnitude seventeen search?”

“I’ll do better. We’ll control the telescopes remotely from here. We’ll use encryption in both directions.”

“We can spread it around,” Shafer suggested. “Route it through half a dozen sites.”

“Flagstaff and Spacewatch Two have preset sky search regions to avoid overlap,” said Kowalski. “I’ll set up the patrol to do likewise. Christ knows we have plenty of unmapped sky.”

Noordhof took a cigar out of a top pocket and started to unwrap the cellophane. “Right. We now have an observing strategy. We know what we’re facing if we can’t find this thing, and we know we’re fighting hellish odds. It’s a start.” He produced a match, struck it underneath the table, glanced at his watch, lit up and carried on speaking all at once.

“I know we all need a break but time’s moving on. So we’ll split into teams. Kowalski and I will set up liaison with Pan-STARRS and the other observatories. McNally and Shafer will come up with a deflection strategy. Do it, I don’t care how. Webb will tell us why we’re going about this the wrong way. Liaise with Leclerc, as he suggests. Sacheverell, you’re due to brief the Chiefs of Staff and the President on the impact scenarios later today.”

“What?”

Noordhof grinned sadistically. “What’s the beef, Herb? You have five hours and maybe you’ll even find time to shave. Prepare something non-technical, maybe a movie. This is your schedule: At thirteen hundred, you’re collected upstairs by chopper and transferred to a jet at Kirtland Air Force Base. You arrive Cheyenne Peak at fifteen hundred and brief the brass. They’re fixing up a little simulation and want your help. At twenty hundred you sit in on a DCI briefing in Washington and at twenty-one hundred you brief the President.”

Sacheverell, looking stunned, appealed to Judy Whaler. He tried another angelic smile. “Can you help me? Maybe with some simulations.”

Judy gulped down the last of her boiled egg, gave Noordhof a look of disbelief and said, “Give me an hour, Herb. I need to talk to Ollie.” Sacheverell scurried out of the room, shoulders hunched, heading either for the conference room or a toilet.

“Please can I have a helicopter too?” Shafer asked.

“Within the hour. Just keep your mouth firmly shut and that includes chatting to the pilot. And make damn sure you’re back here with answers at twenty-one hundred precisely. That applies to all of us.” Webb got a heavy stare.

“I’ve been going through the kitchen cupboards,” Webb said. “Kenneth, you’re brilliantly stocked with spices.”

Kowalski grinned. “Doctor Negi is a regular observer here.”

“We have to eat. This evening I’ll take an hour and make a curry that will transport us straight to heaven. I didn’t mean it that way,” Webb added.

McNally said, “I don’t seem to be getting through to you, Mark. No hardware exists that will enable me to deflect Nemesis a week or a month from today.”

Noordhof blew one of his smoke rings. “I’ll tell you why you’re wrong, Jim. Because if you’re right, we’re dead.”

Judy brushed eggshell from her well-filled blouse. She looked at Webb with wide eyes and said, “Didn’t Herb do well.”

Webb displayed his teeth. The oaf hadn’t uttered a single original thought. He’d missed out on nuclear reactors scattered to the winds; catastrophic chemical imbalances in the atmosphere; invisible, scalding steam sweeping over doomed seaboards. He’d missed out on the typhoid and the bubonic plague which would surely sweep through surviving populations, deprived of the most basic amenities. He’d missed out on the fact that the big tsunami would hit again and again as the ocean sloshed, maybe half a dozen times or more over a few hours. Most of all he’d missed out on the cosmic winter: the darkened post-impact sky, below which nothing would grow; the freezing gales which would turn what was left of America into a blasted Siberian wasteland in the weeks following the crash; and the terrifying risk of a climatic instability which would close down the Gulf Stream and switch off the monsoon, bringing calamity far beyond American shores.

On the other hand, Webb thought, quite a few of these things had been missed by others; and he had to admit Sacheverell had done a moderately competent Internet search. For an idiot.

And now, Webb thought, everybody knows what to expect and it’s simple. There will be little warning. A huge burning mountain will be thrown to earth; it will set the earth ablaze with falling hail and fire; it will darken the sun and moon; and it will plunge us into a smoking abyss.

Vincenzo’s Woman

The sky was still dull blue, and a light early morning mist was hugging the Tuscan fields, when the soldiers of Christ came for Vincenzo.

The monk was awakened by a violent shaking of his shoulders. His woman was over him, her grey hair brushing his face and her eyes wide with fear. “Vincenzo! Robbers!”

He threw back the sheets and ran to the window, pulling open the shutters. Horses were clattering into the courtyard below.

There was a heavy thump from below. It shook the house, and came again. The woman screamed, but the thump-thump continued, and then there was the sound of splintering oak, and running footsteps on the marble stairs. A youth of about sixteen ran into the room. He wore a white jerkin, a white cap and striped black and white tights. He was breathing heavily, had an excited gleam in his eyes, and he was carrying a short, broad-bladed sword. It looked new and unused. He stared at Vincenzo and then turned his eyes to the woman. He seemed uncertain what to do next. He was staring excitedly and kept swinging the sword.

An older man, stocky and bearded, followed him into the room. “Get dressed!” he ordered Vincenzo, ignoring the woman. More men ran in. They started to haul open drawers and cupboards, flinging clothes on to the floor and overturning chairs and tables which got in the way. Vincenzo’s woman threw on a woollen dress, and then grabbed the young man’s arm. Flushing with humiliation, he turned to hit her but stopped as a man, dressed in a long dark cloak embroidered with golden crucifixes, stepped into the bedroom.

The man approached the old monk. “Vincenzo Vincenzi, son of Andrea Vincenzi of Padua, you are under arrest.”

“Why? What have I done?”

“You are being taken to Bologna, where you are to be tried for heresy.”

The woman screamed in fright, and settled down to a torrent of abuse delivered in an increasingly excited voice. The old monk tried to pacify her and finally persuaded a terrified maidservant, peering round the door, to take her down to the kitchen.

The monk had hardly finished buckling his tunic when they bundled him downstairs. An open carriage was waiting. Early morning dew was beginning to steam off the red pan-tiled roofs where the sunlight touched them. A cluster of servants, some of them half-dressed, gaped from the shadows of a cloister. As the carriage clattered out of the courtyard, Vincenzo looked back and glimpsed a cart into which his notebooks and instruments were being tossed — including his perspective tube which, they were later to say, had been invented by the heretic Galileo if not by Satan himself. Minutes later the soldiers, clearly in a hurry, mounted up and galloped out of the courtyard, the cart rattling noisily over the cobbles.

Vincenzo’s mistress had dashed out of a back door from the kitchen just as the soldiers were leaving the front, fleeing along a broad gravel path through a garden scattered with cypress and myrtle trees, statues and tinkling fountains. She ran the two kilometres to her brother’s house and arrived in a state of near collapse. Her brother, a prosperous wool merchant, had a stable with half a dozen horses. A servant saddled one up and she set out for Florence, forty kilometres away, trailed by her brother whose horsemanship was constrained by age and gout. Entering the city through the Gate of the Cross, with the exhausted horse slowed to a trot, she headed for the city centre. She used Brunelleschi’s cathedral dome and the tall bell-tower of the Old Palace as landmarks to find her way to the Ponte Vecchio. Across it, at the Grand Ducal Palace, she dismounted and tied the horse to an iron ring next to a window.

A soldier with a pikestaff, his tunic bearing the fleur-delys of the Medici family, stood at an archway. She approached, almost too breathless to speak. “I must have an audience with His Highness.”

The soldier stared with astonishment, and then laughed. “Franco! Come here. Your grandmother wants a word with the Duke. Maybe he didn’t settle up last night.” A stout man appeared from within, his mouth stuffed and a thick sandwich in his hand. He took in the work-worn hands, the wrinkled face and the cheap woollen dress at a glance. “Try the back entrance. He’s helping out in the kitchens.”

The woman held her hand to her side in pain. “Deny me access, with what I have to tell him, and he’ll have you disembowelled and tossed in the Arno.”

The sandwich man’s amused expression gave way to an angry glare. “Don’t talk to me that way, bitch. Just what do you have to tell him?”

“The words are for His Highness, not his dogs.”

The soldier’s expression of anger was replaced by one of fear. “Franco, is this a witch?”

“Shut your mouth, Steffie. You, wait there.”

“And be quick,” the woman said. “If you want to keep your fat belly.”

Fifteen minutes passed before a tall, thin man of middle age, dressed in black, appeared at the lodge. She curtsied. He beckoned, without a word, and she followed him into the interior of the building, through a large courtyard and under another archway; a door was opened and Vincenzo’s woman followed him into a small anteroom.

“I am the Altezza’s secretary. And you will now explain yourself.”

“Sir, Vincenzo Vincenzi has been taken by soldiers.”

The man sat upright. “The Altezza’s mathematician? What soldiers? When did this happen? And who are you?”

“Sir, I am Vincenzo’s woman…”

“Ah!” Recognition dawned in the man’s eyes. “Of course, I have seen you in the Poggia. Proceed please.”

“It happened an hour, two hours ago, at dawn. The soldiers came. They took Vincenzo and all his books and charts, and his instruments.”

“These soldiers. Describe them.”

“What can I say? They all wore white tunics and caps, and—”

“Soldiers? So far you have described strolling players. Their weapons?”

“Pikestaffs, daggers, arquebuses.”

“Common bandits. If they think they can demand ransom from His Excellency…”

“I thought so at first. But then their leader said that Vincenzo was being taken to Bologna to face trial for heresy.”

The man stood up, staring at the woman in astonishment. “Impossible!” he said to himself. Then: “Wait here.”

Minutes later Vincenzo’s woman was standing outside a door. The secretary turned. “You will curtsy on introduction and dismissal. Address the Grand Duke as Altezza or Serenissimo, and speak only when spoken to. Now, compose yourself.”

Through the door, along a high-ceilinged room and on to a broad verandah where a man and woman sat at a breakfast table with milk, bread, and a bowl of apricots and apples. Servants hovered around, one of them holding a baby. The man was about thirty. He had a bulbous nose, a thick, turned-up moustache and bags under his eyes. The woman was fat and double-chinned, and stared at Vincenzo’s woman with open disdain. The man waved Vincenzo’s woman over. Awestruck but determined, she forgot to curtsy and without invitation launched into the tale of the abduction. The man showed little emotion other than a raising of his heavy eyelids, and waited patiently until she had finished.

“You have done well to inform me so quickly. Enzo, see that she has a ducat or two.”

“Highness, I need only the return of my Vincenzo.”

“At least you will accept an escort back to the villa. And my household will repair the damage these men have done.”

The woman gone, the Grand Duke threw a napkin angrily on to the table. “Barberini?” he asked.

The secretary nodded. “Who else?”

The Grand Duke snapped a finger at a trembling servant. “Get that fat pig Aldo out of his bed.”

The fat pig appeared in a minute, his white hair dishevelled, pulling an indigo-dyed cloak over his red tunic.

“Sit down, Aldo. And use that contorted mind of yours to tell me what game His Holiness is playing.”

“Your Grace, this is an outrage.”

“Do you refer to the abduction of a scholar under my sanctuary, or to the fact that you have been roused from your licentious bed?”

“Sire, the law is clear on this matter. The Holy Office is not free to arrest a heretic outside the papal states without the permission of the secular authorities, who in this case are embodied in the person of Your Grace. This need for permission is particularly so if extradition is involved. This arrest is a gross violation of accepted procedure and an unlawful intrusion on your authority and property. An insult compounded by the fact that this Vincenzo is under Your Grace’s patronage and protection.”

“I have not yet had an answer to my question: what game is Prince Maffeo Barberini playing?”

Aldo continued. “I can think of only one reason.” He paused.

“Well?”

“The one actually given. The Church does not tolerate heresy.”

The secretary butted in: “Serenissimo, it is a warning. If I may speak frankly?”

The Duke nodded, but his expression warned against too much frankness.

“I too have warned you,” the secretary said. “Your patronage of the arts and music is renowned, and it gives many of us joy to see you continue in the great tradition of your family back to Lorenzo. To praise man is to praise his Creator. But this Vincenzo? He is suspected of magic and worse. And Your Grace — forgive me — I have often suggested that you are too tolerant towards Jews and visiting foreigners. There are more Jews in Livorno than any other city in Italy. And many of the foreigners are suspected of being Lutherans.” The secretary hesitated, wondering if he had already gone too far, but the Duke, peeling an apple, encouraged him with a gesture.

“Worst of all, sire, is the clandestine book trade. You allow it to flourish. In the past year, in the streets of Pisa, Lucca and Pistoia, I could have bought prohibited books by arch-heretics like Melanchthon, Bullinger, Brenz and Bucer. I have even seen, with my own eyes, peddlers selling Calvin’s Institutes, Castellio’s De Haereticis, and Luther’s Small Catechism in streets not a stone’s throw from the Duomo. These godless men bring them down over the Alps from the Reformationist printing presses in Geneva and Basel. The abduction of Vincenzo is a warning, sire.”

The Grand Duke stood up and approached to within a foot of his secretary. He was plainly angry, but his voice was controlled. “My dear Enzo, in promising religious toleration I merely continue the tradition set by my grandfather. Through it Florence has flourished; Livorno is a jewel in the Medici crown. And must I remind you that my own father invited Galileo to Florence where he spent the last years of his life? Am I to be denied the same? And why have they taken Vincenzo’s works? To be burned? Will they never be added to the great Library which Gian Carlo, Leopoldo and I have devoted our lives to creating? And are we to stand here discussing my political philosophy while horsemen ride off with a scholar to whom I have offered patronage and sanctuary?”

The secretary bowed. “So, Altezza. Let us intercept Barberini’s mercenaries before they reach Bologna, and hang them at the roadside.”

The Grand Duke turned to Aldo. “Aldo, you are chewing your lip.”

“I expect they are taking him to Rome: why else say Bologna for all to hear? But that is not why I chew my lips. Your Grace, we must be careful here.” Aldo paused, as if gathering his thoughts.

“Note our magnificent patience, Aldo, while we await your words of wisdom and the horsemen flee with my scholar.”

“The Church sees erosion. Erosion of faith. It is being questioned not only by the northern Lutherans but right here in her midst, by men who look at the sky. She has already pronounced on the Copernican heresy. Only last year, when Galileo died, a heretic patronized by your father, the Church forbade you to erect any monument in his memory.”

“Nor did I.”

“Indeed. But what did Your Grace do instead? Buried the heretic’s remains in the Novice’s Chapel at Santa Croce. It is dangerous to provoke a wounded animal.”

“The man who discovered the small bodies which orbit Jupiter, and named them the Medicean planets, deserves honour in return. And the Pope is the lawbreaker here,” the Grand Duke pointed out. “In any case, what can he do?”

“He could induce his unruly relatives to go to war with you…”

“—God preserve me from these Barberinis…”

“… and he could excommunicate you. In that eventuality the citizens of Florence are also bound to be excommunicated unless they remove you from office. Without pardon for their sins, they risk an eternity of damnation. It could create a dangerous situation for the House of Medici.”

The secretary concurred. “Some day this city will sink under the weight of its sin.”

“So. I allow Barberini to tweak my nose? My legal authority to be flouted?”

Aldo said, “Better than blood in the streets, Altezza.” He added slyly: “And His Holiness will not live forever.”

“Aldo, you have the mind of a poisoner. I do not wish to hear more.” The Grand Duke paced up and down in thought. Then he turned to his secretary. “Go to Rome. Ask His Holiness to bless me. Wish him a long and happy life. Aldo is right, as always. I do not seek trouble with the Holy Office. But do what you can for Vincenzo. I do not want him to burn.”

The secretary bowed and turned to leave. The Grand Duke called after him. “Enzo, I do want the return of Vincenzo’s works. Some day they must take their place in the Palatina.”

“And if the cost of saving Vincenzo is a quarrel with the Holy Office?”

The Duke sighed. “Do not bring me back a quarrel, Enzo.”

Piñon Mesa

Noordhof, sensing an atmosphere, said, “Okay you people, take a short breather. Then break into our agreed teams. Reconvene here at sixteen hundred.”

Webb and Whaler noisily transferred dishes to a dishwasher. Sacheverell came back from the toilet. He jacked up a radiant smile. “Hey, Miss Nukey, how about some ping-pong?”

Webb experienced a moment of pure distilled hatred. Judy, however, just shook her head politely. Sacheverell shrugged, and shortly he and McNally were thrashing a ping-pong ball in the common room. Shafer had put some frozen packet into the microwave oven and was watching it intently. Noordhof and Kowalski went into an intense discussion over more coffee.

Webb interrupted them. “Colonel, I have a friend, Scott McDonald, with a robotic Schmidt on Tenerife. I could operate it from here.”

Noordhof’s eyes showed surprise. “You don’t say?”

“I didn’t know it was operational,” Kowalski said.

“It isn’t. It’s still being commissioned, which means there’s no pressure of time on it. It should be free over Christmas. I can link in to Scott’s Oxford terminal, with his permission, and control it from here.”

“I’ll think about it, Oliver.”

It was Webb’s turn to show surprise. “What’s to think about? We need all the eyes we can get on the sky. With a nine-hour time difference we can seriously extend the night sky coverage.”

“There are security considerations.”

“Mark, let’s not get too paranoid. Operating a telescope remotely is what you’re supposed to do with a remote telescope. The control signals will route through Oxford.”

“I said I’d think about it.”

Webb sighed. “It’s your country.” He retreated to his room, had a quick shower and then rummaged in the dormitory cupboard. There was a heavy Shetland wool pullover, left by some visiting observer. Red and yellow lightning stripes weren’t his fashion statement but it was warm.

“Oliver.” Leclerc startled him. The Frenchman was looking worried. He spoke quietly, almost conspiratorially. “Oliver, we have to talk.”

“Sure.” Webb took him into his room and closed the door firmly.

Leclerc looked at Webb uncertainly. “Oliver, there is something very strange going on here.”

My opinion exactly, Webb was tempted to say, but instead waited for him to continue. But Leclerc was judging his man, clearly in an agony of doubt as to how far he could trust Webb.

A brisk knock at the door. “Join me in a run, Oliver? Or are you still feeling fragile?” Judy, bouncing up and down outside Webb’s door.

“One minute!” he called out, and there was the sound of retreating footsteps.

“We’ll talk later,” Webb said quietly.

“We must. But only you and me. Nobody else.”

Judy, in a grey tracksuit, jumped up and down outside the building, waiting for her colleagues. Webb emerged. She beckoned him over, taking advantage of their eye contact to assess him with a swift female intuition. His muscular frame and untidy, curly brown hair gave the impression of an outdoor type rather than the quiet academic he clearly was; subtle lines around his jaw suggested a determined streak, and around his blue eyes an unusual intelligence; but at the same time there was a sort of naivety about him. She sensed that he could be humorous, but that he was also shy, even awkward in company. It made for an interesting and unusual colleague.

Webb trotted over to Judy, stretching in the crisp fresh air and the sunlight.

“This is a working run, right?” Webb said.

“Absolutely!” Judy exclaimed, jumping. “We need it to clear the cobwebs.”

Leclerc appeared a minute later, taking no chances: he was wearing last night’s Eskimo suit. Parisian elegance peeked defiantly over the fur-lined collar in the form of a spotted red bow tie. Webb had never before seen a jogger in a bow tie; unaccountably, the minor eccentricity put Leclerc up in Webb’s estimation.

“Wagons ho!” she called out. They took off on a slow trot down the road.

She smiled broadly at Webb. “That was fun. What gives with Sacheverell and you?”

“Herb is a mafia hit man. He’s a bully, a megaphone, a weather vane, a party apparatchik of the lowest order…”

“But Oliver,” Judy laughed, “he’s our top man in the field.”

“Sure, if you measure scientific excellence by media coverage.”

Leclerc was taking it wide at the hairpin bend, puffing. “Why the seething hatred, Oliver? Academic rivalry? Or did he reject some paper?”

Judy was beginning to speed up. Webb let her get ahead. “Not at all, it’s because I care about truth. Herb rewrites history in a way that would make Stalin blush. He rigs conferences, stuffs his own people on committees, manipulates opinion…”

“Ah, now we’re getting to it,” suggested Leclerc. “He succeeds where you have failed to communicate your…”

“… but his scientific talent is minimal. He’s never had an original thought in his life. He’s put the field back a decade.”

“Oliver,” Judy called over her shoulder, “we don’t need stunning new insights for this one. An identification will do.”

“Herb will try to take over this show and if he succeeds we’ll screw up.”

Judy was now loping. In spite of her shorter legs Webb, beginning to pant, was having difficulty keeping up. Leclerc was beginning to trail. “I think you just like a good fight.”

“My dear Doctor Whaler, you malign me. I’m a quiet academic taken away under protest from an important piece of research.”

“More important than the planet?”

“So, they kidnapped you too, Oliver?” Leclerc asked, catching up with an effort.

“It was more like an offer I couldn’t refuse. What about you, Judy? Don’t they abduct people in flying saucers in this neck of the woods?”

“No abduction. I just drove here from Albuquerque. The Pontiac is mine.”

“Oliver, how many objects are we dealing with out there?” Leclerc was red-faced.

“The known Earth-crossers? About a thousand over a kilometre across. And Spacewatch are finding new ones at the rate of two or three a night.”

“I didn’t know interplanetary space is so crowded. I’m surprised life on Earth has survived.”

“It nearly hasn’t. It was almost wiped out at the Permo-Triassic. Big Daddy’s a mouse compared with some of the stuff out there. Hephaistos and Sisyphus are ten kilometres across. They’d yield a hundred million megatons. But it’s not a simple impact thing.”

Judy was now well ahead. The men were gasping. “Bear track!” she called over her shoulder, and the men followed her off the road on to a narrow path through the trees.

“Not a simple impact, Ollie. Meaning?” The ground under the snow was a soft carpet of pine needles. They had adopted a loping motion and were descending at a fair pace, but it did leave Webb wondering about the return trip.

“Chances are the big ones come in as part of a swarm.” Webb was weaving through low, snow-covered branches. “It’s more in the nature of a bombardment episode, with supercomets disintegrating to dust and choking off sunlight for thousands of years at a time. We think the planetary system is surrounded by a huge cloud of comets, reaching nearly to the stars. The whole solar system, comet cloud included, orbits the Galaxy in a two-hundred-million-year cycle. But as it goes round and round it also goes up and down like a carousel. So, we go up and down through the plane of the Galaxy. Every thirty-six million years we hit the Galactic disc.”

“Which disc we see as the Milky Way,” Judy said, scarcely out of breath.

“I saw it last night. From here it’s brilliant. Anyway, because the Galactic disc has a concentration of stars and massive nebulae, every thirty-six million years when we go through it we get gravitational tides which perturb the comet cloud. The comets are thrown out of their old orbits, they come flooding into the planetary system, the Earth gets bombarded and we have great mass extinctions. Therefore life goes in thirty-six-million-year cycles. Old life is swept away to make way for the new.”

“Not so fast!” Leclerc shouted. They stopped. Leclerc leaned forward, resting his hands on his knees and taking big gulps of breath. Webb looked up. The observatory was out of sight. Their voices were muffled in the snowy woods.

“Alors! All those years you mock the astrologers, and now you tell us our fate does lie in the stars. Where are we now, Oliver, in this great cycle?”

“We’re slap bang in the disc now, and we’re due for another mass extinction.”

“This Galactic connection,” Judy mused. “Is it relevant to Nemesis?”

“Could be. Some of the Earth-crossers are just strays from the asteroid belt. Herb will tell you they all are, but there are also serious people who think that. However I reckon that, because we’re at a peak of the extinction cycle, maybe half are degassed comets. A comet comes sunwards and grows a nice tail so you can see it from a hundred million miles away. But after a time so much dust from its tail has fallen back on to the nucleus that it chokes off. The comet becomes blacker than soot and almost undetectable. It becomes a soft-centred asteroid.”

“I see the relevance,” said Judy, panting a little. “If it’s a main belt stray it’s a cannonball. If it’s a degassed comet it’s a snowball disguised as a cannonball. Get it wrong when you try to deflect it and we have ourselves a nice little mass extinction. If we have no time to drill holes in Nemesis, the big picture becomes part of the equation. Up or down?”

Leclerc pointed downhill, and they set off again, Judy still leading. After five minutes the snow began to thin and the Ponderosa pines were giving way to scrub oak, through which they caught glimpses of sunlit Arizona desert in the far distance.

“Oliver, how should we be short-listing for Nemesis?” Leclerc asked.

“Whatever asteroid the Russians used, it had to be reachable. What could they reach, André?”

“For deep space missions the Russians launch from Earth orbits two hundred kilometres high. Even with Proton boosters, their cosmonauts could not rendezvous with and return from any asteroid with an interception speed of more than”—Judy was leaping over a fallen tree, light as a gazelle “—say six kilometres a second.” The men took it together like a couple of Heavy Brigade chargers.

“That means we’re looking for asteroids in Earth-like orbits, that’s to say low eccentricities, low inclinations and semi-major axes close to the Earth — Sun distance. There are at least half a dozen Nemesis-class asteroids which interweave with the Earth’s orbit. They have plenty of launch windows with? δV in the range four to six kilometres a second, round trip times three months to a couple of years.”

“In energy terms they are surely easier to reach than the Moon,” Leclerc suggested.

“Much. We’ve already soft-landed on a couple. You know, we could check out the orbits of these in short order.”

“Maybe the cosmonauts weren’t bothered about returning,” Judy called back.

That hadn’t occurred to Webb. “A suicide mission?”

“Why not? Save on re-entry fuel, put it into reaching a more distant asteroid. Would you die for your country, Ollie?”

“My love of country is undying. André, say Judy is right. What δV will you give me?”

Leclerc exhaled, “For a one-way ticket? We must relax the criteria to twelve kilometres a second.”

“That means they could have reached anything in the inner planetary system.”

“Merde!” They pounded on down, exhaled breaths steaming.

“There’s another tack,” Webb said. “Very few kilometre-sized asteroids could be diverted on to us. It has to be a near-misser, a potentially hazardous asteroid that already passes between us and the Moon.”

“So what does that do to your list?” Judy asked. They were now half loping, half scrambling down the steep mountainside at speed; by unspoken consent they had abandoned thought of the return climb.

“Depends how big a punch the Russians could deliver and how long a start they had. If they had summoned up a hundred-megaton punch say five years ago they could have gone for quite a few hazardous objects in the kilometre class. There are plenty of asteroids which pass close by. Too many.”

“Like two trains going round intersecting tracks, Oliver,” suggested Leclerc, puffing. “You only have a collision when they reach the point of intersection at the same time.”

They slowed; Judy went down on her backside, and edged down some scree. Webb said, “What you and I ought to do, André, is match past Russian interplanetary probes to asteroids along their track. The further in the past they deflected it, the bigger the shift they could have achieved by now.”

“Good, Oliver. You draw up a hit list of near-missers and I will see whether any of the Phobos and Venera series could have passed close to them, maybe even with a side probe fired off.”

Now they were off the scree and running together down lightly wooded hillside. Inside his Eskimo suit, Leclerc was sweating, red-faced.

“Even a fast flyby,” Judy suggested. “Our kamikaze cosmonauts could have—” she raised her hand and they stopped, almost cannoning into each other. “Did you hear that?”

Webb strained his ears.

“Gunfire,” Leclerc said, and sure enough there was a crackle of shooting down and to their right. It seemed as if several weapons were being fired.

“Hunters?” Leclerc wondered, gasping for breath.

“The survivalists,” Webb suggested. “How far have we come?”

“We must have dropped a couple of thousand feet.” Suddenly, even after their exertions, the woods seemed chilly.

“Maybe we should cut off to the left and find the road,” Judy proposed.

“Let’s take five minutes,” Webb said, glancing in alarm at Leclerc’s beetroot face. They sat down on the pine needle carpet and, joy of joys, Judy produced a large bar of chocolate. The gunfire had stopped. They munched quietly for a while, a little uneasy. Leclerc got up and strolled in the direction the gunfire had been. He vanished into the gloom of the woods.

A couple of minutes later Whaler and Webb were relieved to see him strolling back.

“See anything?” Webb asked.

Leclerc gave a Gallic shrug before flopping down again. “I am not sure. Perhaps some animal.”

“Let’s get out of here,” Judy suggested.

They stood up. The Frenchman glanced nervously back in the direction he had come. “We are lost, yes?”

“Somebody knows where we are,” Judy said looking into the trees on the route they had just come down. A man of about twenty, wearing khaki and green battledress and carrying a long-barrelled rifle with a telescopic sight, emerged from the shadows. A country boy, overweight but with an abnormally thin face smeared with black. The dark eyes in the face were set close together. Webb recognized the eyes as he approached. They were xenophobic eyes, intolerant eyes; they were eyes filled with ignorance and suspicion and the superstition of centuries.

“Mo’nin’. You folks from the Fed’ral Gov’ment?” Spoken through tight, disapproving lips.

“No, we’re just visiting,” Webb said, slipping into an exaggerated Oxford accent. Leclerc would lay on the Parisian and Judy would keep her mouth shut.

“But y’all from up top, right?”

“The observatory, yes.”

The man contemplated that, his close-set eyes flickering from Webb to Judy to Leclerc and then back to Judy. He rested his rifle on his forearm.

“One thang I kin shorely tail is y’all ferners.” He paused, his face expressionless. “Y’ain’t bin spyin’ on us, have you now?”

The Barringer Crater, Northern Arizona

The man stood in shadow, on the floor of the giant bowl, shivering in the cold desert air. Six hundred feet above him, sunlight was illuminating a thin strip of clifftop and creeping down the rock face. He willed it to go faster, but the laws of celestial mechanics remained unmoved. A green lizard looked at him from an eye at the side of its head, and then scurried along an abandoned girder where men long dead had once tried to reach down to the nickel-iron meteorite they thought was buried far under the ground. The chopping sound of the helicopter high above faded as the small, bright blue machine disappeared over the rim of mountain.

The man turned to his companion. “Are there snakes here, Willy? I hate snakes.”

“Welcome to the Barringer crater, Jim,” said Shafer. “Ever been here?”

McNally looked around at the bowl surrounding them. “Seen pictures of it. Please say there are no snakes here.”

“Snakes are not an issue here, Jim. Not like they are in New York, where they smoke crack and carry guns.”

McNally looked relieved. “I believe you, my feel-good index has just gone up.”

“Now the scorpions, that’s another matter.”

“Thanks a million. Why are we here, Willy?”

“I thought a big hole in the ground might lend a little spice to our deliberations. Anyway, genius makes its own rules. We’re a small club, the rest of you can only look on and wonder. Let’s do the tour.”

McNally turned slowly like a lighthouse, gazing at the circular wall of rock which rose six hundred feet above him on all sides. Then he set out after the physicist, making for the base of the wall a few hundred yards away.

“Some impact,” McNally said.

“A penny firecracker,” said Shafer. “A few megatons about forty thousand years ago. There may have been people around.”

“So where are we at, Willy? Do we smash it to rubble with H-bombs?” McNally asked.

“Where did you get that from, Jim, your Los Alamos Workshop or a bad movie? Say you tried that and you ended up with a thousand fragments. Each one maybe a hundred yards across and coming in at maybe seventy or eighty thousand miles an hour. The bits would drift apart slowly but they’d keep close to the old trajectory. By the time they reach us they’d come in as a spray, countrywide. Instead of a rifle bullet you get buckshot, coming in over a few hours. So you don’t get a million megaton shot, you get a thousand impacts instead, each one with fifty thousand times the energy of the Hiroshima bomb. Ungood.”

“I’m still trying to get a handle on this,” McNally admitted.

“Think of America on the receiving end of a nuclear attack. Then multiply by fifty.”

“So let’s take it a stage further, literally pulverize it. Could it be done?”

Shafer started to scramble up the steeply sloping inner wall. “Depends who you listen to,” he called down. “One school of thought says the Earth-crossers are just dried-out comets, maybe even just dust balls. In that case, maybe you could. That’s the Webb line. Sacheverell thinks otherwise. He says they’re strays from the main belt asteroids between Mars and Jupiter. In that case they could be rock or iron and no way could we deliver the energy to smash one up into dust.”

“What’s your view?” McNally asked.

“There was this Crusader,” said Shafer, sitting down. “He wants to show off his strength to a Saracen. So he gets this iron bar and swipes it with his two-handed sword, and the iron bar breaks in two, and he says beat that if you can. So the Saracen gets a silk handkerchief and he throws it up in the air. He holds the blade of his scimitar upwards, and when the handkerchief floats down over the blade it splits in two.”

“That is very poetic, Willy. I like poetic stuff, I didn’t know you were a poet as well as a genius. Maybe if I had a Nobel prize too and a head full of parables I would get your drift, but you see just being an ordinary Joe with an ordinary-sized hat who’s frantically trying to save his country, the significance of this poetic story passes me by.”

Shafer grinned and threw a fist-sized stone playfully down at the NASA administrator. “That comes from running big bureaucracies. Loosen up, Jim, think lateral. So if the asteroid is rocky, when it comes in it hits us like a two-handed sword and we’re blasted to hell. If it’s a dust ball, and we turn it into a powder with bombs, the dust floats gently down like a Saracen’s handkerchief and cuts off our sunlight. We could end up with a few billion tons of dust dumped into the stratosphere. If it’s sub-micron, like condensation from vaporized rock, it blocks out sunlight and we go around in deep gloom. It takes a year for dust to settle out and meantime we’ve killed off commercial agriculture. So our food chain collapses. Experience shows that people without food eventually die. That’s your Saracen option, Jim.”

“If I could corner the market in canned beans… is that lateral enough?”

Shafer clambered down and the two men began a circuit of the Barringer crater. “Forget about pulverizing Nemesis,” said the physicist. “The only way we can handle this is to knock Nemesis off course the same way it was knocked on. We need a controlled explosion.”

“You mean use the debris from the explosion like a rocket exhaust?”

“You got it.”

“How much would we need?”

Shafer glanced at his watch. “I’ll be showing some calculations. If we had ten years’ advance warning, we’d only need to shift Nemesis by a centimetre a second, about the speed of a fast snail. The long-term orbital drift does the rest.”

“Snail’s pace,” repeated McNally. “I like snails, right from the time I was a boy I liked them. My feel-good index has just jumped again. Tell me what you need from NASA. Maybe we could just smash a heavy spaceship into it.”

“Depends how big Nemesis is. I think we have to assume a one-kilometre asteroid, enough to take out the States comfortably. In that case you could do it with a three hundred ton spaceship. It would be a kamikaze mission, crashing into the asteroid at twenty kilometres a second.”

“Three hundred tons!” McNally exclaimed. “NASA doesn’t run to the Starship Enterprise, Willy. And we don’t have ten years, right? Say we reach Nemesis a couple of months before it’s due to hit us.”

“Then you have to shift it at a brisk walking speed.”

“What would that take?” McNally asked.

“Forget kamikaze. Hitting it with the Starship Enterprise fails by a large margin. We’d need to eject billions of tons of asteroid. For medium-strength rock or hard ice, we’d need maybe ten million tons of high explosive.”

“Or its nuclear equivalent. Ten megaton bombs surely exist. So we bury one at some optimum depth…”

“There you go again, Jim, getting your ideas from old movies. Truckloads of mining gear, diesel engines running on oxygen, engineers holding on to a spinning asteroid like the Keystone Kops. No, on any timescale likely to be available to us, burial is not a practical option. We’ll have to be guided by Judy on what a surface burst can achieve. And we still need to know what the asteroid is made of. Say it had the strength of cigarette ash? You’re back to the Saracen option.”

“So test it on the hoof. Zap it with a laser as we approach and get the composition from the spectrum of the vapour, like the Russians did with the Martian satellites. Then use an onboard computer to work out your bomb-placing strategy as you close.”

The physicist shook his head doubtfully. “Even with a nanosecond-pulse laser you’d be lucky to vaporize anything at over a hundred kilometres’ range. That gives your spacecraft maybe three seconds to analyse the spectrum of the vapour, work out the size and composition of the asteroid, calculate the optimal position for the bomb and then actually get itself into a corrected position which might be miles away. Forget it.”

Sunlight was now halfway down the crater wall and a light dew was steaming off, but down at the floor, the bowl was still in shadow and the desert air was freezing. McNally was beginning to feel a sense of oppression, as if the walls were closing in on him.

“How can we?” asked the NASA Director. “You’re telling me Nemesis might be approaching at twenty kilometres a second. We have no launch vehicles which could get out there fast and then slow down to match an approach speed like that.”

“In which case America is about to be exterminated.”

“Damn you, Willy, I have six grandchildren.”

“I’m just as fond of my dog.”

They paced on in silence. After some minutes Shafer said: “What about your big heavyweight, the Saturn Five? As I recall it could just about match the Soviets in booster power. I know you phased it out when the Shuttle came on line, but you must still have the blueprints and the launch infrastructure.”

McNally pulled the collar of his jacket up around his neck. “Sure. The blueprints are on microfilm at Marshall, and Federal Archives in East Point hold three thousand cubic feet of old Saturn documents. And sure, the old launch pads were converted for Shuttle use, but we might convert one back again with a little help from Superman. But Willy, where do we find firms to supply sixties vintage hardware? It would take so long to redesign for modern hardware and modify a pad, we’d be as well starting from scratch with a clean sheet design. You’re talking years.”

Shafer kicked thoughtfully at a stone. “By which time we’re dead.”

“Willy, there are two ways we can approach this. With an unmanned module, or a manned one.” Shafer nodded encouragement, and the NASA Chief continued: “We could build fast from an existing manned module design, or even revamp one from the Smithsonian Aerospace, and get it aloft on a Saturn/Centaur combination.”

“How long?”

McNally pondered. “The moon landings were a child’s game by comparison. The Phase A study alone would take nine months in normal circumstances. I might cut that to three or four. Acquisition planning a month, systems engineering and testing another year. Life support systems are a lot of sweat. Absolute minimum a year to launch.”

“By which time we’re dead,” Shafer repeated. They walked on. The silence in the big bowl was becoming tomblike.

“A shuttle carries people,” said Shafer. “Stuff its cargo bay with fuel. Once the astronauts are in low Earth orbit they could blast themselves into interplanetary space.”

McNally shook his head. “The Mark Three can lift eighty tons of payload into a low orbit. Even if that was pure fuel it still wouldn’t be enough. Look, Willy, ideas for boosting the lift capability of the baseline shuttle are coming out of NASA’s ears. Liquid boosters, carrier pods under the external tank, carrier pods above it, extra side-mounts etcetera. They all need more time than we’ve got.”

Shafer persisted; his voice was beginning to acquire an anxious edge: “Half a dozen shuttle launches, each time with a booster tank in the cargo hold. Fix it so the crews can take the boosters and join them on to a single shuttle like Lego. Skip the test phase”—McNally’s eyes widened with disbelief—“that way you use off-the-shelf systems all the way and all you need is a plumber.”

They were halfway round the circumference. Another lizard scurried away from them, its reptilian legs a blur of speed. McNally threw a stone after it and missed. “I’m sorry, Willy, but you’re now into fantasy.”

The familiar egg-beater sound began to echo off the crater walls as the helicopter appeared, and sank down towards them. McNally waved it away with a grand sweep of the arm, and it tilted alarmingly before veering out of sight. The sunlight had almost reached the floor of the crater.

Suddenly McNally froze. He raised a hand to silence Shafer, an unformulated thought just out of reach. Then he nodded his head, and he said, “I have a very bad idea.”

“Let’s hear it,” Shafer encouraged him.

“The Europeans have a comet soft lander. It’s called the Vesta. It could reach the asteroid.”

Shafer stopped. “That’s a bad idea?”

“The project’s well along and we’re lending them our telemetry systems. Trouble is, their Ariane Five isn’t powerful enough for a soft land.”

“Oh no,” said Shafer.

“Oh yeah. ESA are shipping Vesta to Byurkan. The Russians are launching it for them with a Proton booster.” McNally narrowed his eyes. “They’re building Vesta at Matra Astrium in Toulouse. If we could somehow get our hands on it, without arousing suspicion, we might lift it with a Saturn — Centaur combination.”

“I agree,” said Shafer excitedly. “It’s a terrible idea. A new procurement policy for NASA. Theft.”

“My career would be ruined. I might have to commit suicide,” said McNally happily, his eyes gleaming.

Shafer stopped and let McNally walk on. The NASA Chief Administrator paced slowly up and down for some minutes, muttering eccentrically to himself. He came back, his eyes narrowed. “Willy, we could bring a bomb up on a Shuttle to save payload on the Saturn. The crew would rendezvous with Vesta two hundred miles up and transfer the bomb over before the spacecraft goes hyperbolic. Goddard and JPL could handle the trajectory planning if we ever find Nemesis. Lawrence Livermore have experience with mission sensors and the bomb. I could get the Naval Research Lab to look at the overall mission design. We have our Deep Space Network…”

“Don’t use it,” Shafer said sharply. “The Russians would pick up the ionospheric backscatter. Once this thing leaves the ground it’s on its own.”

“Where am dat chopper?” McNally started to perform a sort of war dance, whooping and staring up at the crater rim. “If it gets me to Phoenix I could connect with New York this afternoon and then a Concorde to Paris…”

“Hey, Jim, calm down. Even if you reached Nemesis you wouldn’t know what to do with it. And something else. Try to acquire Vesta from the Europeans and the Russians will realize we’re on to them. If you’re seen within five hundred miles of Toulouse you’ll trigger a nuclear strike. I’m sorry, Jim, and I’m sorry about your grandchildren, but we’re screwed up before we start.”

Eagle Peak, Tuesday, Late Afternoon

“Let me get this straight,” Noordhof said. “First, the West’s finest brains have so far failed to come up with a strategy to find Nemesis in any reasonable timeframe. Second, even if you do find Nemesis, you have come up with no practical means of delivering a punch to it.”

“Be reasonable, Mark, we’re barely in the door,” said McNally. There was a collective murmur of agreement round the conference table.

Noordhof sighed. “But you only have until Friday night. Where are Kowalski and Leclerc?”

“Kenneth’s gone to bed,” Webb said. “He’ll be observing all night.”

“We left André taking a walk round the grounds,” said Judy. “He said he was meditating.”

“Gone to bed; taking a walk; meditating. Jesus wept, do you people understand the situation?”

“Maybe you should shoot one or two of us, to encourage the others,” Shafer suggested.

“You probably meant that as a joke,” said Noordhof grimly.

“I’m here,” Webb said happily. The backwoodsman from Deliverance, the one with the Fenimore Cooper rifle and the intolerant, ignorant eyes full of medieval superstition, had turned out to be a philosophy student from the University of Arizona in Tucson, in his final year of an MS and writing a thesis on the Influence of the Platonic School on Aristotelian Cosmological Doctrine, a fact which had reminded Webb that you can’t always go by appearances. The astronomer’s backside was still sore from the metal floor of the student’s suspension-free Dodge.

Noordhof stared angrily at the astronomer. “That was an unbelievable breach of security. What right do you people have to endanger this operation by wandering off over the mountain?”

“Nobody ever comes here in the winter, Mark. You said so.”

“Has it occurred to you that the Russians might have feelers out? That a place like this might be under surveillance?”

“Astronomers visit observatories, Mark. It can be Hawaii one week, Tenerife the next, Chile after that. No security breach was involved.”

“Allow me to judge that. As of this moment nobody steps more than one hundred metres from this building without my permission, except to go up to the telescopes.” The soldier turned to Shafer. “Okay. You don’t know where it is. You don’t know how far away it is. You guess it’s a kilometre across and closing at maybe twenty kilometres a second. But now the good fairy comes along and she waves her fucking wand and you find Nemesis some time in the next few days. Then she waves it again and McNally rustles up a launcher and gets a probe out to it. Okay Willy, now it’s up to you. Your mission, should you decide to accept it, which of course you do, is to find some way to stop this frigging thing.”

Shafer rubbed a day-old stubble. “Say it’s coming in on a bullseye geocentric orbit. To miss the Earth, we have to deflect it so that by the time it gets here its orbit has shifted by at least one Earth radius. Six thousand kilometres.” He moved to the blackboard and picked up chalk. A blackboard was the logical way for everyone to follow his logic, but Webb suspected it was also the way he liked to work. “Say we intercept it a week from impact.”

“A week!” McNally gasped incredulously.

“If is the radius of the Earth and t is the time before deflection, you need a velocity increment δV = /t if you want to punch it sideways. A transverse movement of say seven thousand kilometres in seven days comes to one thousand kilometres a day, or forty kilometres an hour.”

“But Nemesis won’t be going in a straight line. The Earth’s gravity will curve it in,” objected Sacheverell.

Webb joined Shafer at the blackboard and they both started to scribble. Webb got there first. “Hey, Herb finally got something right. Gravitational focusing will add to the Earth’s target area. The gravitational target area exceeds the geometric one by 1 + (V_E/V)² where V_E is the escape velocity from the Earth and V is the Nemesis approach speed.”

“But we don’t know V,” McNally complained. “We don’t know how fast Nemesis will come in.”

“We guess. V_E is about eleven kilometres a second and a typical Earth-crosser might hit us at twice that speed. That adds twenty-five per cent to Willy’s estimate. Intercept Nemesis a week out and you need to deflect at over fifty kilometres an hour.”

“Okay,” Noordhof said. “So what does Nemesis weigh?”

Webb and Shafer scribbled, and this time Shafer got there first: “Pretend it’s a rocky sphere a kilometre across, say with density 2.5 grammes per cc. Okay, that means we’re dealing with about — yes, 10¹⁵ grammes. A billion tons.”

“To be knocked sideways at 30 mph,” said Noordhof.

“Without breaking it up,” Webb added. “We can’t shower the Earth with fragments.”

Noordhof said, “Nuke it.”

McNally was looking worried. “That’s what I said. But I’ve been wondering about the legalities of that. As I recall Article Four of the Outer Space Treaty forbids the placing or use of nuclear weapons in space.”

“So how do you think the Russians deflected Nemesis? With a pea-shooter?”

“But the ABM Treaty of 1972…”

“Jim, hear this. Screw all treaties. I include in the screwing thereof the Outer Space Treaty of 1967, the Nuclear Non-Proliferation Treaty of 1968, the Convention on Registration of Objects Launched into Outer Space of 1978 and any other protocols and codicils I haven’t thought of or don’t know about. Let’s just find Nemesis and nuke it.”

Judy Whaler said, “That’s the kind of talk I’ve been waiting to hear. We can blow a big hole in its side, and use the recoil from the ejecta to deflect it. A rocket effect.”

Noordhof said, “You people tell me how big a hole we need.”

McNally said, “With a week’s notice, nobody outside a Bruce Willis movie is drilling holes in it.”

Noordhof said, “In that case you have a surface burst. We surely have empirical data from the Nevada H-bomb tests.”

The NASA Director asked, “With a one megaton bomb, what weight are you asking me to launch?”

“A ton,” Judy replied without hesitation, moving over to a terminal. McNally nodded his satisfaction. They waited as she tapped her way into a web site. “My home page. It’s full of goodies.” She moved the cursor to an icon and clicked the mouse. A table of numbers appeared.

“Here we are. The Nevada tests.”

“But these are tiny explosions,” Leclerc said, looking over her shoulder.

Judy nodded. “Schooner was 35 kilotons, Sedan a tenth of a megaton. But I agree, mostly like Jangle or Teapot they were just a kiloton or two. You don’t want the neighbours screaming when you set off your A-bombs.”

“Can you do a least squares fit?” McNally asked.

“It’s been done.” She clicked again, and a graph appeared on the screen. Shafer got there first: “So, if we believe the fit, a one-megaton surface bomb excavates a crater six or seven hundred metres across. The crater could be as big as Nemesis. We’d shatter it.”

“Maybe, maybe not,” Sacheverell said.

“Let’s run with a megaton for a while,” Webb proposed.

“It is not enough to know the size of the crater,” Leclerc pointed out. “We need also to know its depth before we know the volume excavated.”

Back to the table. A red-painted fingernail traced along a row. “Jangle S was a surface burst. It had a depth about half its diameter.”

Sacheverell said, “These bomb craters were made in terrestrial gravity. How can we trust these results on Nemesis?”

Leclerc was scribbling on the back of an envelope. “Shall we ignore details like gravity? If we extrapolate Judy’s figures we find we could excavate maybe fifty million tons of Nemesis with a megaton bomb.”

“We can also get at it from the crushing strength of rock,” Webb said, “Assuming Nemesis is made of rock. If it takes 5 × 10⁸ ergs to crush a gramme of medium-strength rock, and a megaton is 4 × 10²² ergs, Willy’s bomb has the energy to excavate eighty million tons.”

Shafer frowned. “Once again making a hole as big as the asteroid. Meaning we probably break it into thousands of fragments, and shower America with super-Hiroshimas.”

“Now hold on,” said Sacheverell. He sat down next to Judy and rapidly typed in an instruction. A coal-dark, pitted surface filled his screen. “I’m into JPL and this is Mathilde, a near-Earth asteroid. It has a crater practically its own size and it held.”

“Okay, say for now that we blast a hole in its side and Nemesis stays in one piece. Would it hit or miss?” Noordhof wanted to know.

“We still need to know the speed of the ejecta,” McNally said.

“So let’s work it out. How fast do your nuclear explosions take place, Judy?” Shafer asked.

“The energy release is over in about a hundredth of a microsecond. It comes out as an X-ray pulse. Ground heating is complete in less than a microsecond. The trouble is, it gets so hot in that microsecond that the ground just reradiates most of the energy back. Only about five per cent goes into making a crater.”

Shafer said, “We hit Nemesis with a one-megaton bomb. It stays intact. A twentieth of the energy goes kinetic. So use 1/2mv² and believe André’s fifty million tons of ejecta to get at v.” He scribbled rapidly and Webb let him get on with it. The physicist turned back from the board. “The debris recoils at a hundred metres a second.”

“In all directions,” Webb reminded him.

Shafer nodded his agreement. “The horizontal components of motion just cancel. The actual orbit shifting is done by the vertical velocity component, which will be fifty metres a second. Are you still with us, Jim lad?”

NASA’s Chief Administrator said, “You’re telling me that if I deliver a one-megaton bomb I can blast about five per cent of the asteroid’s mass into space at 50 m/s. Times 3,600 gives me 180 kilometres an hour. So how fast does Nemesis recoil?”

Sacheverell said, “That’s high school stuff. From momentum conversation Nemesis itself is deflected at five per cent of fifty metres a second. Two metres a second.”

“Now hold on,” McNally said. “You’ve just told me we need thirty metres a second.”

Noordhof said, “Hit Nemesis a week before impact and you fail by a factor of fifteen to deflect it with a bomb. It looks like we need to catch this asteroid at least six months or a year out, Willy.”

Leclerc raised his hands in a Gallic gesture. “But for all we know it is only weeks out, maybe even days.”

Sacheverell said, “The Colonel’s right. We need an early warning.”

Shafer shook his head in disagreement. “We need ten or twenty years to map out the near-Earth environment down to the Baby Bears.”

Noordhof’s voice was beginning to border on desperation. “Are you listening? You have to find Nemesis a year out. Your own figures say so.”

“Mark, how do we know it won’t come in next week or next month?”

Noordhof rubbed a hand over his face. “This is bad news.”

Webb rubbed off the equations and scribbled some more on the blackboard. He came back and sat down heavily at the conference table, puffing out his cheeks. “It gets worse.”

Inquisition: the Witnesses

“Are you comfortable, Fra Vincenzo?” the secretary asked.

Vincenzo encompassed the room with a wave of the arm. “I have rarely seen greater luxury outside the Palace of His Serenissimo.”

The secretary smiled. “Better than the cells of the Sant’ Angelo. I suspect they are showing deference to your age.”

“I suspect your own hand in the matter, sir. Not only do I have this fine apartment in the Holy Office itself, I am allowed access to a wonderful library downstairs. If I need to, I may call on the wisdom of St. Thomas Aquinas, Scotus and other great scholars in preparing my Apologia.”

The secretary lounged back on a sofa. “So. They tell me you had a rough journey.”

“I contracted a fever. We had to put up for three weeks in Orvieto. They say I almost died, but I remember little of it.”

“The Altezza is of course concerned for you. He is also anxious that your works should not be lost.”

Unexpectedly, the old monk burst into laughter. “And faced with a choice between my life and my works, which is it to be? No, do not answer, my son. Ferdinand’s love of his library is known to all. And he is right. Human life is ephemeral, but my work — it may be of little consequence, but it will surely outlast these bones by many centuries. To be read and studied by men yet unborn. Can there be a closer approach to immortality on this Earth?”

“I fear they may end up on the Index.”

“I have another fear. Something I fear more than death.” Vincenzo poured a glass of red wine for his distinguished guest, and one for himself. His hand was unsteady. “And that is the torture. I do not believe I could withstand the strappado.”

There was a moment’s silence. The Medici secretary sipped the wine, and changed the subject. “All Florence is talking about your forthcoming trial. The students of Pisa set fire to the Inquisitor General’s carriage with the Inquisitor still inside. There was fighting at the University of Bologna between supporters and detractors of the new cosmology. The authorities called in the mercenaries.”

“That is bad news for freedom of thought.”

“And worse news for you, Vincenzo. The Church may feel that it has to make an example.”

“Is there no place in Europe where a thinking man can be safe? They say that Calvin even set aside Geneva’s laws to have Servetus burned alive. Bruno met the same fate in this city forty years ago.”

“And you repeat not only the Copernican heresies, but also those of Bruno. What a foolish old man you are, Vincenzo Vincenzi.” The secretary stood up. “I will be at the Villa Medici in the Pincio for a few weeks. I have asked His Holiness to bring you to trial within days if possible. You have the right to an advocatus, which the Duke will pay for. I have made enquiries. You will be defended by a man of good family. He is young, but already well spoken of amongst the business community of Rome.” He turned at the door. “If you fear the torture, Vincenzo, put yourself in his hands.”

On the second day of his nominal imprisonment an earnest, round-faced young man, wearing lenses in a wire framework perched on his nose and curled behind his ears, knocked and entered Vincenzo’s apartment carrying a pile of papers.

Keenly aware of his rising reputation, Marcello Rossi regarded the defence of Vincenzo as both an honour and a hazard. The honour lay in the fact that the great Medici family had chosen him. The hazard lay in the fact that the defence of an obviously guilty heretic, if pursued too vigorously, could lead to his own arrest on suspicion of holding the same forbidden beliefs. Between Medici and Pope he would have to exercise extreme care, or be crushed like a fly between two colliding rocks.

Vincenzo’s new advocate came with bad news: the Grand Inquisitor for the trial was to be Cardinal Terremoto. A massive, heavy-jowled man with small piercing eyes and tight, thin lips, his face was so fierce that its appearance was said to have struck terror into a visiting Spanish conquistador. Terremoto was an arch-conservative, a distinguished Jesuit theologian who had studied at Louvain in Belgium in order to familiarize himself with the heresies which prevailed in the North. A man of formidable intellect, he had shown himself zealous in rooting out the heresies which increasingly threatened the Mother Church.

The facts, Marcello Rossi quickly established, could not be disputed. Vincenzo openly declared his belief in the Copernican system whereby the Earth orbited the Sun and was not at the centre of the Universe. The charge against Vincenzo, that he held these opinions, was therefore no more than a plain description of the truth. And since the Holy Inquisition had, in the trial of Galileo some years before, established that the aforesaid beliefs were heresy, denial of the charge would be futile. Vincenzo’s only hope was to abjure the heresy, believe all that the Holy Catholic Church told him, and throw himself on the mercy of the Inquisitor. This the young man strongly advised the old one to do.

His reasoning was sound; but he had reckoned without the stubbornness of his client.

Succinctly, Marcello explained the procedures of the Inquisition to Vincenzo. The trial will be held in secret. Evidence will be presented through prosecution witnesses. You will not be permitted to question these witnesses. You will then be interrogated. If by the end of the interrogation you have not confessed, or disproved the charges, you will be given time to prepare your defence. At that stage, you may call witnesses. But if at that stage you still persist in denial, the young advocate told Vincenzo, nobody will dare enter the courtroom to defend your heresies. The only witnesses who might be persuaded to appear will be those attesting to your upright character and piety. Do you have such? Vincenzo requested Fracastoro of Pisa, an old friend who had known Foscarini of Calabria, the supporter of Galileo. The advocate wrote the name down, and said he would submit it to the Grand Inquisitor.

In what circumstances would the trial proceed to torture? Vincenzo asked, in a voice tinged with fear.

You will be tortured if the evidence indicates guilt which you continue to deny, or if it is thought that your confession is not wholly sincere. Since your guilt is transparent, Marcello said, your only recourse is to purge your soul of the false doctrines and embrace the true beliefs as laid down by the Fathers.

But, said Vincenzo, I believe that the Earth orbits the Sun.

But can you then withstand the torture? Countless thousands of witches, under torture, have confessed to casting spells and curses, to night-flying on broomsticks, to attendance at witches’ sabbaths; and amongst these thousands of confessions, at least a few must have been false and made only to escape further suffering.

Vincenzo stayed silent, and Marcello left him to his thoughts.

That evening, Marcello returned and pleaded with Vincenzo for an hour to confess heresy and throw himself on the mercy of the Holy Congregation. Vincenzo said simply that the Earth is one of the planets, and it orbits the Sun. At the end of the day, with the room darkening and an evening chill drifting in the windows, the young man marched out in despair.

The Pope’s mercenaries came for him an hour after sunrise, when the city was already alive with the clattering of cartwheels on cobbles and the cries of bakers selling their merchandise. They conducted him down broad marble stairs and along corridors to a small chapel, where he received the sacrament from a cardinal who would shortly become one of his judges.

At the very first sight of the assembled cardinals, Vincenzo’s heart sank. There were five of them, five red-robed cardinals, with facial expressions ranging from solemn to grim, seated at a long table made of polished oak.

After the opening prayer, and ceremonies which had no meaning to Vincenzo, he was instructed to sit on a low bench facing the table. The monk was shaking with nerves, and had difficulty drawing his eyes away from Cardinal Terremoto’s face. A notary sat at the end of the table: everything would be recorded, even Vincenzo’s cries of agony should the trial proceed to torture. The courtroom itself was a tall, airy room, its high, embellished ceiling supported by pillars. On the wall behind the notary was a life-sized representation of Christ on the Cross, and next to it a window which, each afternoon, would send sunlight slanting into the great room. Through the window Vincenzo could see the tree-covered hill of Monte Mario, framed on a light blue sky. Sheep were scattered over the hillside; a couple of shepherd boys were playing some game. It was a tranquil picture, far removed from the dark clash between world systems being played out in his own small world.

The first witness of the trial wore the pill-box hat and long cloak of a professor. He had a neat white beard, and he carried himself with the appropriate air of authority. He announced himself as Andrea Paolicci, Professor of Natural Philosophy and Theology at Padua University.

Terremoto opened the questioning. The Cardinal had a deep bass, resonating voice, as if it came from the depths of a crypt. He hunched forward slightly as he spoke, his small dark eyes glittering intensely. “Doctor, do you accept that the use of eye and mind is a legitimate route to the interpretation of Nature?”

“We may approach the Mind of God through all His Works. That is, not only the Sacred Book, but also through His Architecture.”

“And that there cannot be a contradiction between the two, the Book of Scripture and the Book of Nature?”

“Clearly not.”

“You have studied the Copernican beliefs?” Terremoto asked.

“I have, from the perspectives both of natural philosophy and of faith.”

“It is your philosophical perspective which we seek. Doctor, do you find it tenable that the Earth is a spinning ball, a planet like Jupiter and Saturn, orbiting the Sun, with the Sun at the centre of the Universe?”

The Doctor smiled slightly. “I do not. The Copernican system is impossible. The world is fashioned as described in the Bible and as it was understood even before the days of Our Lord, by men of the greatest wisdom and enlightenment. I refer in particular to the teachings of Aristotle.”

“But you reach this opinion on the evidence of natural philosophy, and not simply of faith, or from the opinion of scholars from antiquity?”

The Doctor bowed affirmatively.

“Perhaps we can begin with the hypothesis of a rotating Earth,” said Terremoto. “What is your objection to this?”

The Doctor explained, glancing at Vincenzo from time to time as if justifying his position to the old monk. “If the Earth truly rotated, what would happen to the air? There would be a violent, endless wind. All bodies not in contact with the ground would rush off in one direction. A falling stone would shoot off to the side as it left the hand. And yet, to the greatest precision which the eye can detect, and from the highest towers which we have, a stone falls straight down. There is no perceptible deviation from the vertical. The Earth must therefore, of necessity, be stationary, in accordance with the evidence of our own senses.”

“And the Sun as the centre of all things? With the Earth orbiting it?”

“If the Earth truly orbited the Sun, as Copernicus claimed, then the stars above would reflect this motion. Over the course of a year, each one would seem to move in a small path in the sky. A star at right angles to the zodiac would trace out a circle. One in the zodiacal plane would be seen to move backwards and forwards in a straight line. At intermediate celestial latitudes the stars would trace out ellipses. No such motion can be seen. Therefore the Earth cannot possibly be orbiting the Sun.”

“What of the hypothesis that the stars are like the Sun? That they are not confined to a sphere but scattered through infinite space?”

“If this were so, the stars would be at different distances from us. In that case the parallax effect which I have described would result in the constellations changing shape over the course of a year. They clearly do not. The Bear, Cassiopeia and Orion are unchanging in the sky. The eye and the mind are thus in harmony with the sacred teachings. The outermost limits of the World are set by the crystalline sphere in which the stars are embedded.”

“What then is your opinion of the structure of the World?”

“The structure of the Universe reaches its most perfect description in the Summa Theologica of Thomas Aquinas. The greatest imperfection exists here on Earth. But when we die, the souls of the blessed travel upwards through the heavenly spheres, each sphere of heaven being more perfect than the one before. Heaven, and God, with Christ at His right hand, lies beyond the sphere of fixed stars described by Aristotle. Three orders of angels exist here on Earth, three in the intermediate region, and three in the outermost heaven.”

Another cardinal, Mattucci, asked: “But are the complicated wanderings of the planets over the sky not best explained by the heliocentric doctrine? Do they not account for the retrograde motion of Mars as an optical illusion caused by an overtaking Earth? And is the system of Ptolemy not inferior in this respect?”

The professor said, “I cannot deny that in calculating the positions of the planets the Ptolemaic system is complicated. But even as a mathematical contrivance, the Copernican system works poorly. Copernicus created it on the basis of only a handful of observations. Further, my studies reveal that those observations are not reliable. Many of them have been corrupted by frequent copying from Ptolemy. The latter’s records are a mighty river to Copernicus’s trickling stream. The worst aspect of the Copernican hypothesis is the introduction of a moving centre for the Earth’s orbit, a completely arbitrary device whose sole purpose is to save the hypothesis.”

Mattucci persisted: “But the system is improved, is it not, by the invention of Johann Kepler that the planets move in ovals?”

“Have I a friend in court?” Vincenzo whispered.

Marcello wrinkled his nose sceptically.

The professor said, “That postulate can be made, but only as a computational device, not as a description of reality. Ellipses lack the appeal of circular symmetry. They destroy the harmony of the spheres. And for the planets to pursue these shapes, Kepler postulates the existence of occult forces proceeding from the Sun whereas, of course, the stars and planets are moved by angels.”

The Cardinal Mattucci leaned back to show that he was finished with the questioning. Terremoto took it up. “Doctor Paolicci, apart from the deficiencies of the heliocentric doctrine, which you have so clearly described, do your eyes and mind give you positive reasons for adhering to the Ptolemaic system?”

Paolicci allowed himself a brief, sly glance at Vincenzo. “It follows logically from the rational nature of the Creator. It cannot be denied that a rational, omnipotent Creator will build a perfect Universe. Of course the Prince of Darkness then induced the Fall from Grace, which is an imperfection, but that exploits the weakness of Man and does not affect the structure of the Universe. Only one object has perfect symmetry, in the three dimensions of length, breadth and height which we inhabit. That is a sphere. A perfect Universe built by a rational Creator must therefore be spherical. And only one type of motion is natural in a spherical universe, and that is circular motion. Otherwise the symmetry would be broken. That is why, of logical necessity, planetary motion must comprise circles, and circles upon circles.”

“You do not, then, accept the Bruno hypothesis that the Universe is infinite?”

“An infinite Universe is unthinkable.”

“And the plurality of worlds? Men on Bruno’s planets?”

“Such could not have been descended from Adam, nor could they obtain Christ’s redemption.”

Cardinal Borghese took up the questioning. He looked at the prisoner and his lawyer with open hostility before turning to the professor. “Doctor, you have told us that no contradiction is possible between science and faith.”

“No Christian can believe otherwise.”

“And if a contradiction were to arise?”

“Eminence, with respect, since no such contradiction is possible, your question is without meaning.”

“An apparent contradiction, then?”

“Since actual contradiction is impossible, the appearance of it can only arise in the mind of the Turk, or the Jew, or the heretic.”

Borghese turned to the notary. “Let it be recorded that Vincenzo is neither a Turk nor a Jew.”

A succession of witnesses from universities in Bologna, Pisa, Naples and Venice was then summoned, all saying much the same thing. By midday the room was becoming hot and stifling, and the court was adjourned for four hours.

In the apartment, the young advocate flopped on to the same settee which the Grand Duke’s secretary had occupied the previous week. “You have an impressive list of enemies,” he said.

Vincenzo gestured with open palms. “Academics are prone to jealousies. And much is at stake. But I also have many supporters.”

“Unfortunately, Father, your supporters dare not support you in court, while your enemies appear to have gained the ear of Boniface. Why else would you be on trial?” Marcello reached for an apple in a bowl and started to toss it playfully in the air. “Your old friend Fracastoro — the acquaintance of Foscarini.”

“Yes?”

“He is refusing to testify on your behalf, even on the matter of your piety and character. My courier tells me the man is terrified.”

“Have I no friends?” Vincenzo asked in despair.

“Perhaps one. The Cardinal Terremoto was told of your predicament with regard to witnesses. At once he instituted a diligent search and has at last found someone willing to testify to your character. I did not find your friend’s name.”

“Thank God for a small blessing. But it seems I will have to make the scientific case myself.”

The advocate took a bite at the apple. “A case which has already been rejected by this same Congregation when Galileo tried to make it a few years ago. Confess to error, Vincenzo. The alternatives are too horrible even to mention.”

“Can I retract the truth, my son?” Vincenzo headed for a small bedroom off the apartment. The advocate put the apple core in the fruit bowl, loosened the belt around his stomach and stretched out on the couch.

The court convened again in the late afternoon. A clerk awakened them and led the old astronomer and his lawyer down the stairs and along the corridors.

There was only one witness. A small, stooped man in priest’s habit, with a hooked nose and dark, blotchy skin, hurried into the room. Vincenzo turned to Marcello Rossi in alarm. “Grandami!” he whispered. “What is that man doing here?”

“He is your character witness.”

“What? But this man is my sworn enemy. He hates me. Who has done this to me?”

“Terremoto.”

At that moment, Vincenzo knew he was doomed.

The Martians

Then it reached them.

The two generals and the civilian watched from the comfort of their brown leather armchairs as the combat crew frantically checked through their systems, mag tapes spinning and a babble of messages flooding in. The winking red lights had vanished from the map. The lists of refuelling points and aircraft aloft reappeared. The Blackjacks were almost home. The MiGs were far out over the Sea of Japan. The Kola peninsula was deserted. Winton was cool, Pino was grey and sweaty. Hooper, the Chairman of the Joint Chiefs of Staff, noted with disapproval that someone was hyperventilating.

A telephone rang, the pink one. Wallis observed his own hand trembling as he picked it up.

General Cannon was looking down, telephone to his ear. “Put me on loudspeaker.” Wallis pressed a button and the general’s voice boomed round the room. “April Fool,” it said.

“Sir?” said Wallis, looking up at his commanding officer. Mortified, Wallis found that his voice was as shaky as his hand.

“Somebody just stamped on the mountain. Roof sheared clean off and fell on you. You’re dead, son.”

“General Cannon, what was that?”

“Martians,” the voice boomed.

“Men from Mars?” Incredulously. The combat crew, to a man, stared up at the general.

“Affirmative.”

“Sir, Martians aren’t allowed. They’re not in SIOP.”

“Foggy, how do you know there are no little green men out there? We wanted to test how the system reacted to something crazy and the only way was to spring it on you. Operation Martian Scenario. Y’all did just fine. We have you on home movies and it’s a whole lot of use to us upstairs. You and your crew’ll have a full debriefing at the end of this shift. Then maybe you’ll want to get drunk.”

Wallis was aware of the eyes of his combat crew on him. In the confines of the steel office, the rage, fear and bewilderment were tangible. He took a deep breath and a chance with his career. “General Cannon, sir, with respect. Damn you to hell.”

There was an electric silence. Then a deep, genie laugh echoed round the office. “Son, I’m already there.”

“Doctor Sacheverell, your assessment?” Cannon asked.

“I’ll need to run a few Monte Carlo simulations. But at a first guess I’d say prompt casualties two hundred million. Dead that is,” said the civilian. “Two sugars, please.”

“Nice one,” said Cannon, pouring coffee. “You’ve solved the population explosion.”

“We’d be looking for a few survivors in freak conditions,” Sacheverell continued. “People down mines, stuff like that. Material devastation with this scenario is quite severe though. Maybe cities reduced to dust or rubble over fifty per cent of mainland USA.”

Hooper and Sacheverell might have come from different planets. Whereas Sacheverell was thin and stooped, Hooper, the Chairman of the Joint Chiefs, was almost as wide as he was tall. Where Sacheverell had a greasy complexion, Hooper had a deeply wrinkled, tanned face. Where the astronomer had a shock of vertical red hair and a headband, the soldier’s hair was short, white and fine. Where Sacheverell dressed like a basic slob, with an untidy grey suit and garish red tie on a turquoise shirt, the soldier was immaculate. And where Sacheverell was stirring coffee, Hooper banged a fist angrily. Coffee spilled into the saucers. “Almighty Christ, am I supposed to believe this? Rubble? Dust?”

“And there’s no question of any industrial or political infrastructure surviving,” Sacheverell added, hastily picking up cup and saucer.

“Cool it, Sam. Doctor, talk about the C-cubed systems,” Cannon said.

“With this particular scenario, they collapse. But it is a bit way out and in general I can’t be sure. I’d have to get into some heavy analysis on ionospheric plasmas and I don’t have time for that.” Nor the competence, Sacheverell added to himself. “I guess you have to expect a big electromagnetic pulse over most of the country.”

“This is pure crap,” Hooper said, flipping through the pages of Sacheverell’s hastily constructed scenario. “Our command systems are nuclear hard.” In a flash of inspiration, Judy Whaler had laid the report out like a film script, fictitious descriptions of fireball impacts linked together with phrases of the “Meanwhile in San Diego” type. Appended to the Hollywood scenario, and bearing as much resemblance to it as Dr. Jekyll to Mr. Hyde, was a spartan appendix written in the measured language of science, liberally sprinkled with equations, tables, ifs and buts. The CJCS, Sacheverell noticed, was sticking to the film script.

“Not hard enough,” Sacheverell said. “A successful Russian first strike only delivers five thousand megatons, most of that near the ground. For all we know there’s a million megatons on the way in. Even at one per cent efficiency, that’s like a million amps under a potential of a million volts flowing overhead for ten seconds.”

Cannon stirred his coffee thoughtfully. “That would melt your fillings, Sam.”

Hooper shook his head angrily, as if rejecting the whole concept. “PARCS and PAVE PAWS would have picked your asteroid up on the way in.”

Sacheverell shook his head too. “Your radar software filters out signals with long delay times, so you only pick up stuff very near the Earth. It wouldn’t have shown up on the radars until the last minute.”

“So? We’ll re-programme.”

“You could, at the risk of swamping the computers with small space junk. Even so military radars have a limited range. By the time they detected the asteroid it would be a couple of hours from impact, far too late to stop it. Anyway, you have practically nothing covering the southern sky.”

Cannon said, “Look, Sam, anything we got into the air would get its wings ripped off even if we were C-cubed operational. This applies to TACAMO as much as Bomber Command. I can’t even guarantee we could contact Mitchell’s Trident fleet in time.”

“Let me get this right,” said Hooper, bewildered. “Are you seriously telling me that if this thing hits we’re wiped out and we can’t hit back?”

“Mitchell’s fleet would mostly survive,” said Cannon, “but so what? The point is, the thing would just be a great natural disaster. You heard Wallis on the phoney NORAD circuit: there was no attack, no enemy, nobody to hit back at.”

The Chairman, JCS, stood up. He walked over to the window and looked out through the Venetian blinds. The rasp of a Prowler penetrated the triple glazing and the room trembled, very slightly. He turned, his back to the window.

“Realistically, how much warning do we get?”

Sacheverell put down his coffee. “If it approaches the night hemisphere you might see it in binoculars an hour before impact. Assuming you knew exactly where to look. It would be visible to the naked eye maybe fifteen minutes from impact.”

“Mister, what I want to know is, when do the phones start ringing?”

“When you see it as a bright moving star. Say twenty seconds from impact.”

Hooper sat down again, and stared into the middle distance for some moments. “Well it sure beats the hell out of Star Wars,” he said at last.

“Sam, it’s beautiful,” said Cannon. “The thing is undetectable, practically into our air space before we know what’s hitting us. When it does hit us, we’re obliterated. There’s no point in hitting back even if we could because, like you say, it’s just a freak natural disaster. Sam, you know I’m due to meet some senators from the Appropriations Committee in a couple of hours. I’m trying to get final approval for Bat-strike.”

“Which we’re selling on Middle East scenarios.”

“Fifty billion bucks down the tube, along with the new Grand Forks, our Navy, SAC, brilliant pebbles, C-cubed, all our surveillance systems, the whole BMDO. Everything we have, this thing beats it. And they don’t even have to worry about retaliation.”

“I don’t believe it,” repeated Hooper, grey-faced. “This is fantasy stuff.”

“And we reckon they set the whole thing up for a day’s defence budget.”

“What’s the timescale for this?” Hooper asked harshly.

“Heilbron thinks the Russians have pulled it off already,” said Cannon. “It’s somewhere out there now, on the way in.”

Downstairs, the shift was nearly over. The normally ebullient Pino had been unusually quiet, wrestling with some inner problem. Finally he said: “Colonel, do you know anything about astronomy?”

“Not much, Pino. What do you want to know?”

“Well, are we sure there are no men from Mars?”

“Relax, Pino, there are no Martians. Vince Spearman said it on TV.”

Pino seemed to be examining the arcane names on the screen in front of him. Then: “This guy Spearman — he’s okay?”

“AOK. He’s been checked out real good.”

The sergeant relaxed.

Eagle Peak, Tuesday Evening

Webb said, “If Nemesis is more fragile than a rock…”

Sacheverell groaned. “You’re not still on that comet crap. Ever heard of the asteroid belt?”

“Which fails to give us the periodicity in the extinction and cratering records.”

“What periodicity?” Sacheverell sneered. “There is none. And how come Toutatis, Mathilde, Eros and Gaspra are rock?”

“Mathilde has the density of water. It’s a friable sponge.” Webb turned to Noordhof. “Colonel, Herb will tell you to plan on diverting a solid rock. But if it’s a degassed comet and McNally fires an H-bomb at it, we’ll end up with a dust ball heading for us. When the ball comes in it will incinerate the upper atmosphere as it slows from cosmic speed to zero. It’ll remove all the ozone. Then it’ll take a year to sink through the stratosphere and during that year the Earth will be wrapped in a highly reflective dust blanket. Down here we’ll be in twilight. We’ll have a major climatic upset. Freezing gales will blow from sea to land. The continents will end up looking like Siberia. We might cut the thermohaline circulation in the Atlantic and switch off the Gulf Stream. If we do, that will feed through to a permanent snowfall in Eurasia. That will switch off the monsoon. Nobody in Asia will eat for a year or so. You’ll shift masses of water to the poles as ice and change the spin rate of the Earth. Maybe you’ll flip the geomagnetic field, and set off seismic faults and vulcanisms worldwide. Then when the dust clears you’ll be exposed to the full unshielded UV of the Sun, and you’ll have a global catastrophe on top of a global catastrophe. Herb’s certainties could do us in.”

“Maybe we want to get it right before we launch a bomb at it,” suggested Shafer.

Leclerc was looking puzzled. “I always thought comets had tails.”

“Not when they’ve degassed, André. They may crumble to dust but there are plenty of well-authenticated cases showing that they sometimes turn into asteroids.”

Leclerc said, “If we find Nemesis, could we tell its internal constitution by looking at it? Using Kenneth’s monster telescope? What do we actually know about the reflectivities of the Earth-crossing bodies?”

Sacheverell said, “We don’t. But the museums are stuffed with meteorites. They’re fragments of asteroids and they’re rocks.” He shot Webb a venomous look.

Webb said, “You don’t have comet debris in the museums because it breaks up in the atmosphere. Nemesis could be like Halley, with a crusty exterior and a fluffy inside.”

“Fluffy snowballs, right?” Shafer asked, narrowing his eyes. “Dust and ice in equal proportions?”

Webb nodded. “Give or take. Try to nuke it and you end up with a billion tons of dust. Look, if we get this wrong we could reduce the species to foraging bands.”

McNally’s face was a caricature of dismay. He said, “I go for Sacheverell’s theory.”

Noordhof spoke, in a thoughtful tone. “Ollie. Do you realize what you’ve just said? That if Nemesis is a comet, the interests of the world at large are best served by letting the USA take it? Are you saying we’re on opposite sides, Ollie?” Noordhof asked softly, playing with another cigar. Suddenly the air was electrically charged. Judy, at a terminal, stopped typing and swivelled on her chair to face them.

McNally broke the stunned silence. He gulped, “Hey, if the Russians changed its course without turning it to dust, so can we.”

Webb shook his head tensely, his eyes locked with Noordhof’s. “They probably had years of a start, letting them push it a few centimetres a second, without setting up big internal stresses.”

Judy Whaler turned back to the terminal. “A standoff burst! With neutron bombs!” she sang out over her shoulder, and carried on typing.

Webb blew out his cheeks with relief. “Thank you, Judy. Colonel, we just handle Nemesis with the utmost care. We use a standoff burst. Ablate a skin with neutrons.”

The relief was palpable. Shafer was scribbling. “Maybe yes, maybe no. Even a neutron bomb emits X-rays and they get to the asteroid first. If they create a sheath of plasma the neutrons might not get through. I don’t know that neutron bombs would help.”

She swivelled on her chair. “We do bombs at Sandia, Willy. We can handle the computational side. Neutron bombs are the ultimate capitalist weapon, remember? They’re designed to irradiate people, not destroy structures. Suppose instead of positioning a bomb on the surface of Nemesis we detonate it during a flyby, say a few hundred metres up. Instead of forming a crater, the top few centimetres are vaporized and blown off. The stresses are spread over a hemisphere instead of concentrating around a crater.”

Shafer said, “So we bathe the asteroid with neutrons and X-rays. And if it turns out to be a comet, we might still do it gently enough to preserve its structure.”

Noordhof asked, “Can we do it? Can we do it?”

Webb suggested, “Try a one-megaton burst at five hundred metres’ altitude and suppose the bomb energy is all in neutrons.”

Judy unconsciously swept her blonde hair back over her shoulder and said enthusiastically, “Neutrons get absorbed within twenty centimetres. If they just passed through you they wouldn’t do damage. It’s because they get absorbed within your body that they make such brilliant weapons. The energy will be deposited in a top layer of Nemesis around the thickness of a human body.” She turned back to her terminal.

You’re a bundle of fun, lady, Webb found himself thinking.

Shafer drew a circle and a point some way off, and tangent lines from point to circle. Webb saw what was coming and tried to keep up on a sheet of paper. Shafer said, “Give Nemesis a radius R and put the bomb a distance d from its centre. We need to know how much of the bomb’s energy is intercepted by Nemesis.” He scribbled rapidly and said, “Seen from the bomb Nemesis fills πR²/4πd² or 1/4(R/d)² of the sky.”

McNally said, “If we explode the bomb five hundred metres up, like Ollie says…”

Shafer continued, “Then we have d = R and a quarter of the bomb energy is dumped on the facing hemisphere of Nemesis. That’s good. Now let’s skip the detailed trig and suppose the irradiation goes to a mean depth of five centimetres.”

Webb took up the story. “So we’re imagining that over the hemisphere facing the bomb, a surface skin maybe five centimetres thick takes twenty-five per cent of the blast. The concentration of energy will be prodigious.”

Shafer rapidly substituted numbers for symbols in a formula. “Okay so about half a million tons of surface regolith is exposed to a quarter of a megaton of neutron energy, coming in at a third the speed of light.”

Sacheverell asked, “Can we turn that into a speed?”

“Easy. Each exposed gramme gets a few times 10¹⁰ ergs, about the same energy as dynamite. So the surface goes off like dynamite. It turns into a vapour expanding at five kilometres a second.”

“Now you’re talking,” said Noordhof. He was leaning forward intently, trying to follow the rapid exchanges between the scientists.

“It’s as if you’ve spread a three-inch sandwich of dynamite over a hemisphere,” McNally repeated, his eyes gleaming. “A puff of vapour expanding at five kilometres a second from one side of Nemesis. It’s Christmas after all.”

Webb said, “Hey, imagine exploding like dynamite when one of Judy’s bombs goes off.” Noordhof shot him a cold glance.

McNally returned to an earlier formula. “On the week-before-impact scenario, that would shift Nemesis at two metres a second. We’re still well short.”

“But we’ve gained a power of ten,” Shafer said. “Maybe we could even use a bigger bomb.”

“No,” said Webb. “You’d bust it up.”

“I agree with Ollie,” said Judy, turning back again from the terminal. “Hit the asteroid and it rings like a bell. If you hit it so hard that its velocity change is more than its escape velocity then you’ll break it up.”

“Now you’ve lost me,” said Noordhof.

“Imagine the asteroid as a fragile bell, made of glass or something. The Russians tapped it with a pencil years ago and made it ring. But now it’s rushing at us and we’re having to shift it with a hammer.”

Shafer said, “You’re forgetting that it might have internal strength. Jim, if you can rendezvous with Nemesis a hundred days before impact we might be able to deflect it in principle, maybe even if it’s one of Ollie’s degassed comets. Fifty days, maybe. Ten days or less and we’re in trouble whatever it’s made of.”

McNally sounded as if he was in pain. “A hundred days? Willy, can we get back to the real world here?”

Sacheverell said, “Cracks and fissures in rock could change the whole story.”

Judy turned to them, a satisfied smile on her face. “We’re in.”

“Where?” Webb asked, startled.

“Welcome to the wonderful world of teraflops, Ollie. While you people are handwaving I log on to God. I fix up a simulation algorithm using Sandia’s own shock physics hydrocode, and they run it for me.” McNally pulled the curtains half shut to cut down on stray light, and they clustered round her terminal. She logged in through a series of gateways, each one with a different password. “I’m using fifty million finite elements and all nine thousand processors. Give me the internal constitution of your comet or asteroid, cracks, fissures and warts, and I’ll tell you what happens when you neutron it. Look on my works, ye Mighty, and despair!” She paused, a finger over the keyboard.

“Hey, you read Chaucer?” McNally asked.

Judy raised her eyes to heaven and then pressed the carriage return button with a flourish. “Even the Teraflop will take some minutes.”

Noordhof, looking at the blank screen, said, “It seems to me, people, that the critical thing is the internal constitution of this asteroid. Is it rock, iron, ice or what?”

“That’s the sharp end of the debate,” Webb agreed.

Noordhof said, “I get the impression you guys don’t know a lot about what’s out there.”

Webb agreed. “Here be dragons. But it’s vital.”

The screen came to life. Judy said, “I want to show you three simulations. Here’s number one. I’m exploding a megaton four hundred metres above a one-kilometre rock with the tensile strength of a carbonaceous chondrite.” On the little screen, a potato-shaped, black mass appeared. It rotated slowly for a few seconds, as if being viewed from an exploring spacecraft, and then froze in position. A brief flash filled the screen. The rock shuddered. Black fingers spread out in a cone. When the debris had left the screen, a sizeable hole had appeared in the side of the rock, which was drifting slowly off to the left. “This is very satisfactory. The nuclear deflection has worked.”

A second potato appeared on the screen, identical to the first. “Okay, this one is stony, silicon oxide. I’ve made it a fragment of a large asteroid which has been pounded over geological timescales: it’s been weakened. It has internal fissures. It’s just a rubble pile.” This time, when the debris had cleared, the rock had fragmented. Half a dozen large fragments, and dozens of smaller ones, were drifting slowly apart.

Noordhof said, “That looks like trouble.”

Judy nodded. “Deep trouble. It depends how early we could deflect Nemesis.”

“If we ever find it,” said Leclerc.

A third potato materialized. “Now the last one, this is a comet with the tensile strength of the Kreutz sun-grazer. Let’s see what happens.” The bomb flashed briefly. Instantaneously, the potato disintegrated. But there were no fragments to fly apart. Instead, a white amorphous mass gradually filled the screen, apparently growing white hairs as it approached. “All we’ve done is generate a dust ball.” The simulation ended. McNally opened the curtains and bright daylight streamed into the room.

Shafer moved over to the window and looked out. “I seem to remember the Sandia people carried out Tunguska fireball simulations some years ago,” he said over his shoulder. “And the 1908 data were best fit by a rocky asteroid.”

“But there were counterarguments,” Webb reminded him. “For example the lack of rocks spalling off along the trajectory, and the coincidence with the Beta Taurid comet swarm. And with a small change in the assumed trajectory they could accommodate a comet.”

Shafer asked, “What do the spectra say about the Earth-crossers?”

“There are hardly any available. They’re too faint.”

“Okay,” said Noordhof, resuming his place at the head of the conference table. “From what you people are saying it seems to me that I can come to an immediate decision. There’s too much at stake here to take chances. We have to invent something that will work whatever Nemesis is made of.”

“We could play with all sorts of deflection scenarios,” Judy said. “Solar sails, laser propulsion, kinetic energy impactors and so on. Either they take far too long to develop or they can’t deflect in the time available. Only nuclear weapons stand a chance, but as you’ve seen they could give us a cluster of debris or maybe even — if Nemesis turns out to be an old comet — a blanket of dust and a cosmic winter.”

“Hell,” said Sacheverell, “even a pure rock asteroid would give us that after it fried us.”

Noordhof put his hands on top of his head. “Am I going mad here? You are telling me the following: One, you will have to deflect Nemesis at less than a metre a second or it will break up and shower us with fragments. Two, you will have to deflect it at more than ten metres a second or it will hit us.”

“Depending on how far out it is,” Shafer said.

“And you can’t even guess that?” the Colonel asked.

“How can we?” Judy raised her hands. “We need to discover the thing.”

“Which brings me to Three. You have no hope of finding it on any timescale likely to be useful.”

“Pending discovery, we could adopt a hundred-day guideline for interception,” suggested Judy.

McNally was in pain again. “This hundred days you keep bugging me with…”

Noordhof reminded them: “It’s not the hundred days. The White House, in their infinite wisdom, have given us until Friday night. And this is Tuesday night, and so far you people have come up with zilch.”

Wisconsin Avenue, 20^h00 Eastern Standard Time

The Salem Witch screamed as she hurtled along the runway, her headlights picking up only snow rushing out from a point in the dark, and her wheels throwing arcs of slush high in the air. The screaming faded as the little executive jet slowed to a crawl. The pilot taxied bumpily along to a slipway and turned, slipping the Gulfstream in between the parked jumbos and 707s; an inconspicuous dwarf amongst the giants flying the flags of all the world.

They were in a dark corner of Dulles International Airport.

Human forms flickered in silhouette beyond more dazzling headlights. Three men stepped down from the aircraft. Two were in uniform; the third man, a civilian, was clutching a shiny new briefcase to his chest. A sudden gust caught the leading officer’s hat and he cursed briefly as he snatched it back from the bitter wind.

Traffic was light and the black Lincoln Continental took them fast and skilfully into town. The driver wore a naval uniform. There was no conversation. Along Wisconsin Avenue the car slowed, turned and halted, its headlights illuminating a wrought iron double gate straddled by a metal spider eight feet wide. The spider’s legs were white with snow. A second car, which had followed them discreetly from the airport, drove on. They waited while a camera appraised them from atop a gatepost. Then there was a metallic click, the spider split quietly into two halves and the car sighed on to the inner approach road. They drove through a grove of white-laden trees, lit up by red, white and blue spotlights, and effectively shielding the CIA Director’s home from curious eyes and laser microphones.

The avenue curved round to the back of a large, dark house and stopped at the door of a conservatory, lit up from within and throwing an orange glow into the surrounding woods. The three men climbed wearily out of the car, which drove off, its tyres scrunching over the snow. The leading officer opened a glass door and they were met with a surge of hot, foetid air. They walked, single file, along a narrow paved path taking them through dense jungle foliage, past a tinkling fountain and over a small bridge. Colourful fish with long diaphanous fins swam in the pond below. There was a strong smell of narcissus. A slice of Guatemala, preserved in the Washington winter.

There was a sandy, cactus-strewn clearing in the jungle and an elderly man, wearing an oversized grey pullover, was sitting at a circular table, smoking a pipe. He waved them towards white garden chairs around the table. A moth was throwing a giant frantic shadow on the table as it circled to its doom around the light overhead.

The Director’s wife came out with a tray of iced tea and biscuits. She had long blonde hair and the slim, elegant frame mandatory for the Washington hostess. The civilian, Sacheverell, guessed she was about fifteen years younger than her husband. She could have been on the cover of Vogue, he thought, about twenty years ago.

A breast brushed lightly over his shoulder as she leaned over him with the tray; the light physical contact tingled his nerves. She said, “Don’t forget your tablets, honeypie.” The Director growled and Sacheverell watched her slim form disappear through the French windows. The moth sizzled briefly overhead.

Sacheverell took stock of the evening’s company. There was Honeypie, alias Richard Heilbron, the Director of the CIA, tapping out his pipe on an ashtray and looking like a professor in some provincial university. There was Samuel B. Hooper, Chairman of the Joint Chiefs of Staff, a small, burly, white-haired man who looked as if he had been born radiating authority. And his companion, the gaunt, self-effacing Colonel Wallis who, with his combat crew a few hours earlier, had been tossed in a fire and grilled like the moth.

“Gentlemen, welcome,” said Heilbron. “How was your Martian Scenario, Sam?”

“A catastrophe. Foggy here manages a threat assessment conference with NMCC and Offutt, they deduce that there’s a blast coming from Mexico, and then they’re dead. There was no counterstrike, no nothing.”

“You got nothing away? Not even a Trident?”

“Not even a frigging rowing boat. If the Russians have pulled this off…”

“As you know we’re due to brief the President at twenty-one hundred. I understand we’ll be in the East Wing theatre and I’ve had your movie set up there, Doctor Sacheverell. What I want to do is go over the CIA evidence with you in advance.”

“Rich,” said Hooper, “I still think this is the most crack-brained tale I ever heard. I hope I’m about to hear some damned hard evidence.”

“What you’re about to hear, Sam, is guesswork. Open the folders in front of you, gentlemen. Look at the top two pages. Now this is a translation of a conversation in Russian intercepted by Menwith Hill a couple of weeks ago. It’s an exchange between the cosmonauts aboard Phobos Five and their mission control in Tyuratam.”

“Phobos Five?”

“Is a deep space probe which the Russian Republic launched six months ago with three men aboard. Their declared intention is to head for Mars, get into a low parking orbit, launch a couple of probes and come back in one piece. It’s a two-year round trip. Ever since the days when there was a Soviet Union we’ve known they would try for a manned landing on Mars early in the millennium and this looks like a prelude. It all fits nicely.”

The declaration of a nice fit, Sacheverell thought, came with a hint of world-weary scepticism.

Heilbron nodded towards a small cassette tape recorder on the table. “In this tape the cosmonauts are one week out. Three point three million kilometres away. Speed of light is three hundred thousand kilometres a second. Listen, and try to follow the transcript.”

There was a lot of static. Every few seconds a metallic bleep cut through the sound. Then a voice, speaking in Russian. Putting their weariness aside, Sacheverell and the officers followed the script intently:

Heilbron rewound the tape. Hooper picked a winged insect out of his tea and flicked it into the shadows. He said: “It’s a bit late for quiz games, Rich.”

Wallis said: “The guy on board answered pretty damn smart.”

Sacheverell, who had also noticed the fact, looked at the colonel with respect. He said: “Distance is 3.3 million kilometres. With a speed of light of three hundred thousand kilometres a second, that gives a round trip, from the question asked at Tyuratam to the answer intercepted at Menwith Hill, of twenty-two seconds. It fits with all the pauses except the last one.”

“I can see we’re in smart company tonight,” Heilbron said. “Excellent. We can use all the brains we can get on this one. Yes Sacheverell, all the pauses except the last one. What is that horrible noise? Then there’s a nineteen-second delay and the reply, ‘Vyssotsky is singing.’ ”

“Meaning?” Wallis asked.

“Now hold on, Heilbron,” General Hooper interrupted. “Are you trying to tell me the cosmonaut answered the question before he got it?”

“Precisely.”

“Christ, Sam, maybe Menwith just screwed up their tapes.”

“Negative. We’ve checked out the technical side.”

“What’s your conclusion, Mister Heilbron?”

“Patience, Colonel Wallis, there’s more, much more. We hadn’t paid a lot of attention to the Phobos launch until then, you understand. Plenty of stuff on tape etcetera but processing it wasn’t a high priority. The timing hiatus had been picked up by one of my bright young geniuses, a guy by the name of Pal. So I put him in charge of a small team, a sort of Operation Phobos. They found this — listen. This is from a conversation three days later. I haven’t bothered with a transcript. Listen to the timing pulses.” They listened to the high-pitched, frightened bat, coming between the deep Slavic tones of the man in the spaceship. Heilbron replayed it several times. The military men shook their heads. Sacheverell frowned.

“It’s impure,” he said. “Structured.” He was beginning to feel light-headed, whether from tiredness or the narcotic effect of the scented narcissus he couldn’t tell.

Heilbron nodded encouragingly. “Another Brownie point for our young friend. Now here’s the same timing pulse slowed down ten thousand times.” He wound the tape on, missed the start, wound it back again and then played it. Sacheverell felt the hair on the back of his neck prickling as the clandestine message came over, a clear, Morse-like, intelligent signal spreading out from the circle of light, through the Guatemalan jungle, over the big lawn and into the dark woods beyond. Heilbron let it run a minute and then stopped it. He said:

“They’ve slipped in a burst transmission. It goes on for hours. I’ve had my best people on it for a week, fifth-generation machines trying to talk to it. It even beat the NSA’s Cray T3D at Fort Meade.” Sacheverell recalled that more mathematicians were employed at the National Security Association’s Maryland headquarters than anywhere else on Earth. Heilbron went on: “The consensus now is that it’s some sort of one-way encryption system, unbreakable unless you have the key. And the conversation is phoney — the voice people tell me the acoustics aren’t quite right or something. What’s up there on Phobos Five is a tape recorder. They’re playing some sort of charade, ground control asking questions in anticipation of the answers on the tape. Only the tape carries messages and the guy on the ground mistimed, just once.”

“What are you telling us? That the Soyuz is unmanned?” Hooper asked.

“Three cosmonauts climbed on board. We took pictures.”

“Jesus, Rich,” said the Chairman, JCS, in exasperation. “First you tell us some machine on the spacecraft is answering pre-set questions, then you say there are people on board. Why don’t they just do their own talking instead of playing an answering machine?”

“Because they’re not there any more.”

Hooper gave the CIA chief a sceptical stare. “They jumped out?”

Heilbron said, “Take a look at Exhibit B.” There was a rustle as envelopes, about a foot square, were opened. Sacheverell, baffled, helped himself to more iced tea. The CIA Director produced a small red pill from a packet and swallowed it with his tea.

“Like I said,” Heilbron continued, “nobody was paying much attention to Phobos at the time and the pictures you’re going to see were just filed away at first. Look at the first one. This came from the French. It’s an unclassified Spot picture. What you’re looking at is the Baikonur cosmodrome. The scale’s about a hundred miles. Aral Sea’s off the picture to the left. The river”—a thin blue ribbon wandered left to right across the picture, passing through a city—“is the Sar-Daya.”

“What’s the town?” Wallis asked.

“The former Leninsk. It’s a hundred miles east of the Aral Sea. Following the Red Army takeover, the whole region has been closed again to Westerners. Leninsk is one of the new science cities: cinemas, culture palaces, sports stadiums and so on. They’ve built it on to Tyuratam old town — that’s the darker colouring on the left.”

“What are the arrows?” Wallis again.

“The one in the middle is the Cosmonaut Hotel. We’ve a first class source there, a lady who’s been with us since the old days.” Heilbron’s pipe gurgled and he poked at it. “Now look at the next few pictures, Sam, and despair.”

There was a rustle and Sacheverell found himself looking at a large black and white photograph with a “classified” stamp on its border. Heilbron continued: “You can just see the railway line and the highway next to it coming in from the bottom. It’s a busy line, all the way up from Leninsk. The big grey squares you see in the middle are the Soyuz assembly buildings. We think the ones on the left are for type G and Energia assembly — the brute force boosters. Now the tracks go further north and the railway line carries on. The next photo”—more rustle—“shows the launch complex. The little arrows show what used to be their ICBM silos before Salt Two. Mostly the old SS-X series. Forget them. It’s the Energia facility that’s got me running to the john. You see it in the next picture. We’d taken routine high-level reconnaissance pictures of the launch, and this was taken by a big Bird on a perigee passage. The thing that’s circled”—there was something like a full stop with a white circle round it—“is a military transport. You see the launch vehicle just to the right. On the next photo you see them putting up netting over everything. They’ve got something to hide.”

A cluster of tiny dots, each one a man, was scattered around between the vehicles. They seemed to be pulling something over the ground. “The netting’s up in the next picture. Perspective has changed a bit; we’re using a different satellite.” The same pattern of buildings was there, but now they were throwing long evening shadows. Cloud had edged in and some of the ground was obscured. A solitary dot threw a long shadow on the ground, arms and legs clearly visible. Sacheverell thought he could detect a moustache.

“They screwed up. Look at the next one.” The next one showed the netting in place, hiding truck, rocket and launch pad from prying satellite eyes. The sun had almost set.

“What am I supposed to see?” asked Hooper.

“Look at the shadows,” said Heilbron. “The sun was shining under the netting. My geniuses used the outline of the shadows and the angle of the sun and they got the next picture.” They stared uncomprehendingly at a large Rorschach ink blot; Sacheverell thought he saw a squid with a huge quill pen.

“Now to me this looks like an ink blot,” said Heilbron, to Hooper’s evident relief. “But my genuises tell me these are the shadows of four men, the rocket, launch gantry, and a lifting crane. Use the computer to deproject and subtract out everything but the thing they’re lifting and Voila!”

“A carrot!” exclaimed Hooper, staring in bewilderment at the final, blurred computer picture.

“That’s right, Sam, it’s a carrot,” said Heilbron triumphantly. “It’s two metres long; they’re loading it under netting and they’re taking it to Mars.”

Wallis said, “I have it.” He pushed back his chair, stood up and paced up and down, staring into the middle distance. Then he came back, staring at Heilbron, and nodding his head in agreement.

“Well?” Hooper snapped.

“Some carrot, sir,” said Wallis.

Heilbron half-smiled. “Got it in one. Let me tell you about the carrot, Sam. Look at the last picture. It’s a nice present from our lady in the Cosmonaut Hotel.”

It was a black and white photograph. It had been taken through a door slightly ajar, the camera had been held about two feet back from the crack. Three men, dressed for a Russian winter, their fur hats and coats fringed with snow, stood at the reception desk.

“The little guy with specs is local, just reception for the other two. The guy with the Astrakhan hat we haven’t yet identified. But the other guy we do recognize. His name is Boris Voroshilov, former lecturer in physics from Tbilisi, now employed at Chelyabinsk-7. He designs nukes.”

“Richard…”

Heilbron raised his hand and continued. “Phobos Five is a cover. Somewhere out there the cosmonauts have sent an automated probe with a tape recorder on to Mars on the old orbit. Meanwhile our heroes have slipped their moorings and set out into the blue yonder on a new orbit, complete with carrot. Only it isn’t a carrot, Sam, it’s a ten megaton hydrogen bomb.”

Sacheverell said, “I know of only one application for a hydrogen bomb in deep space. Deflecting an asteroid.”

Heilbron pointed the end of his pipe at the JCJS. “Tell me something. Why would Zhirinovsky want to do a thing like that?”

Hooper’s face was like an executioner’s.

The CIA chief hammered it home: “Sam, we’re going to get it right in the Kansas breadbasket.”

Inquisition: the Interrogation

The priest settled into the witness’s chair. The notary said: “Identify yourself to this Congregation.”

“I am Jacques Grandami, of the Jesuit Order. I teach theology and natural philosophy at a number of colleges in France.”

Terremoto began the questioning: “You are acquainted with Vincenzo Vincenzi?”

Reptilian eyes flickered briefly in Vincenzo’s direction. “I know him from the school of theology in Paris, and later in Bologna.”

“What is your opinion of the man?”

“He claims to be devout.”

“Claims to be?”

“I cannot say that he is not. He has the outward appearance of piety. In Bologna he took part in the choral recitation of the divine office, and in the daily recitation of faults.”

“Why then do you seem to hesitate over his piety?”

“He is extremely disputatious, lacking the spirit of humility. He scorns reasoned argument which does not fit his opinion. He thus shows manifest contempt for the arguments of Scheiner, Ciermans, Malapert and other Jesuits against the Copernican system, which he advocates even though, as this Congregation knows, it has been condemned as false. Komensky of Prague, in his Refutatio Astronomiae Copernicianae, has written a brilliant refutation of the heliocentric doctrine. But Vincenzo refuses to acknowledge its intellectual force. Instead he has spoken to me, with approval, of the Bruno heresy that the Universe is infinite and that the stars are suns, with planets and living creatures on them. In addition to his false advocacy, he is not, I regret to say, true to his order. He belongs to the Order of Preachers but does not preach. He has taken a vow of poverty and yet lives in a villa provided by the Duke of Tuscany. He has taken a vow of celibacy but shares a bed with a woman.”

Terremoto made to dismiss Grandami but one of the cardinals, a man with a light freckled skin and an accent which seemed to place him in the far north of the country, stopped him. “One moment! You have said that you are a theologian.”

“I am, Your Eminence.”

“Then perhaps you can answer this question. What is the basis, in the Holy Scriptures, for belief in a stationary Earth?”

Grandami smiled unpleasantly. “How could Joshua have commanded the Sun to be still if it was not moving in the first place? Does the Psalmist not describe the Sun as going forth in a circuit to the ends of heaven? Does Job not write of the pillars of the Earth trembling?”

The cardinal bowed. “Thank you, Jacques Grandami. The Peace of Our Lord go with you.”

The interrogation began on the second day, without preliminaries. A row of grim faces met Vincenzo as he was guided to his bench. Cardinal Terremoto opened the proceedings. His piercing eyes were fixed on Vincenzo, and the corners of his mouth were turned down in an unconcealed scowl. Vincenzo felt his legs shaking and his stomach in queasy knots.

Terremoto looked right and left. “This Holy Congregation is now prepared to question the prisoner. Before we proceed, does the advocate have anything to say on the prisoner’s behalf?”

Marcello turned to his client. He whispered, “Recant, Vincenzo.”

The monk shook his head.

“Recant and throw yourself on the mercy of the court. All these people want is a public abjuration.”

Vincenzo’s head was lowered. Almost imperceptibly, he shook it again.

Marcello stood up. Terremoto’s small eyes were glaring into his own; the hostility was undisguised, bearing down on the young man like a physical force. The lawyer, fear gnawing at his heart, took an instant decision which he knew would affect his future career and forever change the life of his client. “Your Eminences, I regard the guilt of my client as sufficiently well established by these proceedings. As he persists in denying his guilt, and shows no sign of contrition for his erroneous beliefs, I must ask to be relieved of the duty to defend him.”

The cardinals murmured between themselves. There was some nodding of heads. Then Terremoto said, “Your duty to the prisoner is discharged. Leave us with good conscience.”

“Marcello!” Vincenzo cried out in shock. But the lawyer avoided the astronomer’s gaze, and Vincenzo could only watch as his former advocate picked up a sheaf of papers and scurried out of the courtroom, eyes to the ground and bent almost double. He momentarily buried his face in his hands.

The lawyer had hardly left the room when Terremoto began the questioning. “On whose authority do you state that the Earth rotates?”

“My lawyer has sold his soul.”

“Answer the question.”

“Authority? That of my eyes and brain, Eminence.” Vincenzo’s voice was shaking.

“I ask of written authority.”

“Your Eminence, the English monk Bede stated that the Earth is a ball floating in space a thousand years ago. Nicolas Oresme, over three hundred years ago, stated that the Earth is round and rotates about an axis. And the same was said by Cardinal Nicholas Cusanus over two centuries ago. They even say that Aristarchus and Eratosthenes…”

“Do you read Greek?”

“No, Eminence.”

“You therefore rely on hearsay, do you not?”

“I rely on generations of scholars produced by the Mother Church, from Reginbald of Cologne to the Jesuit writers of today and even such as Fra Paolo Foscarini of the Carmelites.”

“But amongst the heathen scholars of ancient times, does Aristotle not stand head and shoulders above the rest?”

“Eminence, you know that is so.”

“And have you studied his Physics and Metaphysics?”

“I have, in translation, and there he commits himself to a belief in an Earth around which the universe rotates. But I believe that view to be in error.”

“But did not Thomas Aquinas, four centuries ago, show that Aristotle’s system is compatible with the Christian doctrine? And is not Aristotle the foundation of natural science throughout the Christian domain? Is it not then possible that the error is yours?”

“Aristotle did not have the benefit of the telescope. Nor the record of centuries of planetary motions which we have.”

The Inquisitor looked down at some notes. The room was silent. The sound of a chirping cricket drifted in from the garden. And then Terremoto suddenly sprang a trap: “Do you deny that the Bible is the supreme authority in the affairs of philosophy?”

“I believe that the Bible is intended to teach men to go to heaven, not how the heavens go.”

“Ebbene! What presumptions are hidden in that neat phrase! Are you also qualified as a theologian?”

“I did not say that, Eminence.”

“You have, however, just seen fit to make a theological pronouncement. The Council of Trent, in its Fourth Session, was explicit about where authority lies: the Word of God is to be interpreted strictly according to the unanimous consent of the Fathers. I repeat my question.” Terremoto looked across at the notary, who read out in a high-pitched voice: “Do you deny that the Bible is the supreme authority in the affairs of philosophy?”

Vincenzo, colour drained from his face, said, “Eminence, I do.”

There was an audible gasp from one of the younger cardinals. Terremoto continued: “Is it also your opinion that the Holy Spirit has allowed the Holy Mother Church to be misled for the nineteen hundred years since Aristotle?”

Another trap, this one with steel teeth.

If Vincenzo replied yes, that the Church had received no guidance from above, then this was akin to denying the Virgin Birth or even the existence of God. If he said no, that the Holy Spirit could not have allowed such an error, then he was admitting to a wilful disregard of the teachings of the Church. Either answer would surely lead to the same fiery end. The notary leaned forward, his face screwed up in anticipation of recording the reply. The cardinals waited. The cricket outside the window chirruped on.

Vincenzo’s voice was little more than a murmur: “Your Grace, that is a theological question. I am incompetent to answer.”

Terremoto was relentless. “And yet you claim to be a devout Catholic. Did you not consider it your pious duty, even before meddling in hypotheses which attempt to revise the received wisdom of the Church, to ask such a question?”

“I believe with Doctor Paolicci of Padua that the mind of the Creator can be read in His Creation.”

“Do you accept that man was created in God’s image?”

There was an expectant silence. After the heresies they had heard, the cardinals did not know what to expect of the wretched old man who faced them. But Vincenzo simply said, quietly, “Of course, your Eminence.”

“Then how can he be otherwise than at the centre of the Universe?”

Vincenzo murmured something, wringing his hands as he did. The notary asked him to speak up, but the monk remained silent.

“The alternative diminishes mankind, does it not? And opens the door to unthinkable heresies?”

“God has two books, that of Nature and that of Scripture. They cannot contradict each other. I read the book of Nature. It says what it says.”

The remainder of the morning was taken up with a close interrogation on technical matters, on the precision of the Alfonsine Tables, the precession of the equinoxes, the motion of the eighth sphere, the angular sizes of the fixed stars, their lack of parallax and the fantastic stellar distances then implied in the Copernican system, and on the meaning of Christ’s sacrifice to creatures on the supposed other worlds of Giordano Bruno. Terremoto dominated the questioning throughout, his deep-chested voice booming through the courtroom. He showed himself to have a remarkable grasp of the scientific issues. Only the cricket outside the window seemed uncowed: unimpressed by the Cardinal’s powerful voice, it chirruped incessantly. By the time the court recessed, it was early afternoon and Vincenzo was drenched with sweat.

That evening, Vincenzo was offered the chance either to confess and recant or take five days to prepare his defence. To the Grand Inquisitor’s astonishment, Vincenzo refused both options. Instead, he made a simple statement. It was brief and to the point. He hesitated briefly, feeling the weight of the Inquisition’s hostility crushing down on him like a collapsing house, but then began to speak, his voice quavering but determined.

“I deny the simplicitas of Aristotle’s universe, whereby the Sun, Moon and planets orbit in epicycles upon epicycles about a stationary Earth. Through the Galilean tube, we see that the Moon is imperfect. It is pitted with craters. With our own eyes we see mountains and valleys like those on Earth. If the Moon is like the Earth, then the Earth is like the Moon. It is therefore just one of the heavenly bodies. The four Medicean planets, revolving around Jupiter, are the clearest proof that not everything revolves around the Earth. We see too, with the tube, that Venus goes through all the phases of the Moon, with the illuminated crescent always turned towards the Sun, and so clearly orbits the Sun and not the Earth. If our Earth is a heavenly body like the Moon, and also a planet like Venus, then we too must orbit the Sun.

“This Holy Congregation has referred to Aristotle, Ptolemy and the Holy Scripture as witnesses for the central position of the Earth. Aristotle also stated that the heavens are immutable. But did we not see a new star in 1572, one which was born, rose in brightness and then died? And if he was wrong in one astronomical matter why can he not be wrong in others? As for Ptolemy, have the new discoveries of the great navigators not made his geography obsolete? Why then should his chart of the heavens not be equally so? Many wise philosophers throughout history have believed that the Earth moves and the Sun stands still.

“As to the Scriptures, we should heed the warning of Saint Augustine, who tells us not to be concerned when the astronomers seem to contradict the scriptures. It implies only that another interpretation must be sought for the Sacred Texts. Pererius, of the Collegio Romano, tells us that non potest Sacrarum Literarum veris rationibus et experimentis humanarum doctrinarum esse contraria. In any case, what are we to make of the words of Job: ‘Who moves the earth from its place?’Your Eminences are not trained in natural philosophy and are not competent to make judgements in that realm. In the interpretation of the world, it is the book of Nature which we must read, not that of the Holy Scripture.”

A tangible ripple came from the cardinals’ table. Vincenzo, his die cast, carried on. “I believe that the stars are made of fire. There are many more stars in existence than those we see. The perspective tube of Galileo resolves the light of the Milky Way into myriads of stars. These must be suns like our own, at immense distances. That is why the constellations do not change and the stars do not trace out ellipses in the sky as the seasons progress: the stars are at such immense distances that the parallax is too small to be seen. You declare that the Earth is stationary as a matter of faith, and that I am therefore a heretic to hold otherwise. But suppose that, in years or centuries to come, the astronomers prove beyond doubt that it is the Sun which is stationary and that the Earth moves around it? Then you who try me, the cardinals of this congregation, will be seen as the heretics. The Mother Church will be exposed to scandal, and forced to reverse Her doctrine, and Her enemies will delight in exposing Her to ridicule. Eminences, you commit a grave error in making matters of faith out of astronomical questions.”

The old man flopped down, drained. The cardinals, virtually accused of heresy, sat stunned. Terremoto’s expression had gone through all the stages of amazement, horror and finally outrage as Vincenzo’s audacious statement had proceeded. Their Eminences filed out without a word.

That night, Vincenzo slept not in the luxurious apartment of a Holy Office official, but in a damp cell in the Castel Sant’ Angelo. And while he slept, his judges discussed his case by candlelight, and decided on their next step: the territio realis.

The White House, East Wing Theatre, 21^h00

Sacheverell sat, his stomach churning, in the front row of the little theatre. The door opened and a tall, elderly man peered in. His shirt sleeves were rolled up and he was wearing an outrageously multi-coloured waistcoat.

“Coffee, son?” the old man asked.

“Thank you, sir. Two sugars.” The man shuffled out. Minutes passed, while Sacheverell’s mouth dried up. Then the door was opened with the push of a foot and the man reappeared, a paper cup in each hand. He sat down beside Sacheverell and passed a cup over. The astronomer noticed that the old man had one sock black, one blue.

“Two sugars. Now before we get started. We’re farmers; we’re bankers; we’re lawyers. Me, I’m just a country boy from Wyoming. So keep it simple.”

“Will do, Mister President.”

“Okay. This will be new to most of the people here. I’ve had a preliminary briefing from the Secretary of Defense and he tells me this asteroid thing will devastate us when it hits. But what does he know? You’re the horse’s mouth, son, and that’s where I want to hear it from.”

“I’ll do my best, sir,” Sacheverell gulped.

The President grinned. “What is an asteroid anyway?”

“An asteroid is a lump of rock, sir, going around the Sun just like the planets. They’re a few miles across and blacker than soot, very hard to find. Maybe there are a thousand or two big ones in orbit between the planets. It could be half a million years before one of them hits the Earth but when it does you get a giant explosion.”

“How giant?”

“Say a big one hit Mexico City. The blast wave would hit us here at three hundred miles an hour. Now with an ordinary explosion, say from a bomb, the blast is just a sudden wind, over in a fraction of a second. But with this one, a wind following the blast would go on for hours. Air temperature while it’s blowing would be four or five hundred degrees Centigrade, more or less like the inside of a pizza oven.”

“That was quite a speech, son. But I thought you said these things are only a few miles across.” The President’s country-boy grin had faded as Sacheverell had talked.

“It’s their speed, sir. You have to think of it as a big mountain covering twenty miles every second. When it hits the ground it vaporizes in about a tenth of a second. You could get half a million megatons easy. I’ve prepared a movie which should give an idea what to expect.”

The door opened and half a dozen men wandered in and spread themselves around the little theatre. Sacheverell had spoken to two of them, Heilbron and Hooper, only a few hours previously. Heilbron caught Sacheverell’s eye and nodded. The Secretary of Defense sauntered over and sat down beside Sacheverell. He was about fifty. Away from the television cameras, Sacheverell noticed, Bellarmine had a slightly jaundiced complexion and a receding hairline. “Hail!” he said. The Chief nodded amiably. Sacheverell, wedged between the President of the United States of America and the Secretary of Defense, felt his skin tingling.

Heilbron walked over. “Mister President, I’ve got a movie.”

“Okay let’s get into this,” said President Grant. He finished the coffee and crumpled the paper cup, letting it fall to the floor. “Seems we’re in for a matinée performance.”

Heilbron stepped up on to the dais and picked up a short pointer. The lights went down. Maps and photographs appeared in succession on the screen. Heavy-jowled Slavic faces appeared under fur hats. Heilbron kept waving the pointer flamboyantly. A shaky amateur movie showed a military transporter leaving some camp surrounded by a tall barbed-wire fence; another showed tarpaulin-covered train wagons being hauled across an icy, blasted landscape. When the dark conical shape of the hydrogen bomb appeared the President said “Stop!” and the movie froze, the black shape filling the screen in blurred close-up.

Grant stood up, the picture of the bomb illuminating his face and chest. “Jesus, is that it?”

“Just about, Mister President. We’ve intercepted a coded message from Phobos but it’s got us beat.”

“Rich, this strikes me as paper thin.”

“Sir, we’ve often had to act on less. I believe the balance of probability is strongly tipped towards a hostile act against us.”

“By whom?” The Russians alone? Khazakhstan? The whole damned Federation?”

Heilbron shrugged.

“Just what is the significance of this?” the President asked, turning grimly to Sacheverell.

Sacheverell put down his cup and walked nervously to the dais. Heilbron sat down wearily in Sacheverell’s chair, and the President sat on the edge of the little platform, his knees crossed. Suddenly, in the half-light, the astronomer found himself facing men who had shed their homely television faces, men with calculating eyes, and ice in their veins, and powers beyond those of the gods. He fought back a surge of near panic.

“Sir, it is technologically possible to divert a near-Earth asteroid on to a collision course with any given country.” Sacheverell realized with horror that his mouth had dried up, he was almost croaking. “It would take state of the art technology and extreme precision. The technique would be to blast some material off the asteroid at an exact place and time, diverting its orbit. The problem would be controlling the devastation, which could spill over into neighbouring countries. My movie illustrates a range of possibilities. Movie, please.”

The projector whirred quietly at the back of the room. Mysterious numbers and crosses appeared on the screen. A black and white title read

The title disappeared, replaced by a grid of lines covering the bottom half of the screen. The only movement was a tumbling of numbers on the top right of the screen, next to a label saying Lapsed time =. The audience waited.

A green spot came in rapidly from the top. It struck the grid. The lines buckled, and formed a hole with a raised rim. Green splodges hurried off the edge of the screen. Away from the hole the grid of lines was vibrating at high speed, like a violently shaken jelly. The lines vanished and there was an old movie taken at the Nevada test site. There was a timber-framed, Middle America house. At first, nothing was happening. But then the paintwork started to smoke, and curtains were burning. And suddenly the house was splintered wood and smoke streaking into the distance and Sacheverell was saying this is what to expect a thousand kilometres away.

Now there was a coloured map of the USA, with cities marked in bold font. Circles were radiating out from a spot in the middle of Kansas, like ripples on a pond, as if the map were under water. The numbers were loping along in minutes now, rather than seconds, and Sacheverell was saying you expect Richter Nine up here on the Canadian border and down here in Chicago. The map disappeared and more old footage followed; this time the camera was panning over horribly flat rubble. A few dazed individuals in Arab dress stared at the camera. Others were crawling over a mound of debris, like ants over a hill. Sacheverell was saying of course these are stone houses and we can’t be sure this applies exactly to New York or Chicago but you would surely cause massive destruction coast to coast. He was aware that he was beginning to gabble but he couldn’t help himself. His voice was now a croak.

Then of course there’s the fire, he said, rising to the tension he sensed in his audience. About thirty per cent of the land area of the States is combustible in the summer and twenty per cent in the winter. You would expect thousands of fires over an area the size of France. They could merge into one giant conflagration so you would take out the whole of central USA with flames from the exposure to the rising fireball and this is Hamburg during a firestorm only with red hot ash thrown over the whole country you might set the whole country alight and then of course there’s the biomass the biomass yes especially as fat melts at forty-five Centigrade I mean Celsius but they’re the same really you expect living people to fry in their own fat over most of the States your skin will bubble and peel off in a few seconds and then your blood and water will boil and then your fat will combust and you will just carbonize while the blast is sweeping you along at the speed of a jet.

The audience sat riveted.

Now the movie was showing something that looked like one of the more lurid products of a Hollywood studio. An ocean was boiling. Now the boiling green lines formed into a pattern; they reared up into a wave, a tumbling, foaming breaker which washed over little cartoon skyscrapers like a wave over pebbles, and Sacheverell was saying we’re not sure about the stability of waves that big but we’re working on it with the Sandia teraflop but a splash like this off the Eastern seaboard would wash over the Eastern States but the Appalachians would stop it and you would be okay in Bozeman, Montana. Then there were more flashing symbols, the projector stopped whirring and the lights went up. Sacheverell swallowed nervously, blinking in the light.

His audience remained frozen.

“You got casualty estimates for this, son?” The President finally asked, quietly.

“Hard to judge, sir. Most of the USA is less than two thousand kilometres from Kansas. A million-megaton bang on Kansas I reckon would leave two hundred million casualties from the prompt effects.”

“You mean injured?”

“No sir, dead.”

“What about survivors?” the Vice-President asked.

“With this scenario one to ten per cent of North America would survive the initial impact. But they would have big problems. Mainly lack of food, medical care and sanitation. I reckon most of them would be taken out with starvation, typhus, cholera, bubonic plague, stuff like that.”

“Comment, anyone?” the President asked, turning round.

“What you’re saying,” said the Secretary of Defense, his features drawn tensely, “Is that the technology is available to create a weapon a million times more powerful than a hydrogen bomb?”

Sacheverell nodded.

“You’re some sort of nut,” the Secretary of Defense said.

“It only takes a gentle push, sir. There are plenty of these asteroids around. The trick is to find one that passes close to the Earth. Then you soft land a small atom bomb on it. If you explode the bomb on the right place at the right time, you nudge the asteroid into an Earth-crossing orbit. It doesn’t need much. With a mid-course correction — a second explosion with a small atom bomb or even conventional explosives — you could target the asteroid to within a couple of hundred miles.”

Grant turned to Heilbron. “You say they’ve pulled it off already?”

“In my opinion it’s on the way in now.”

A slim, hawk-nosed man in his late fifties, wearing an expensive, dark three-piece suit, was standing at the back door of the theatre. He spoke angrily. “In the name of God, Rich, you’re telling us we’re at war.”

Grant raised his hand quickly. “Not here, Billy.” He turned to the DCI. “How many people know about this?”

“The seven of us in this room, two of my staff, and one of General Hooper’s aides. On the European side, about an equal number. About twenty people in all. And a team of eight trying to find the thing. They’re hidden away in a mountaintop observatory in Arizona.”

“Doctor Sacheverell, we know where to reach you?”

“Yes, sir. I’m one of the team, in Eagle Peak Observatory.”

“Don’t even discuss this with your dog. Gentlemen, that applies to us all. I want no apocalyptic statements, no veiled hints, no unusual moves. Nathan, Sam, the Green Room at 3 a.m.”

“With respect, sir…”

“Nathan, I’m about to entertain guests. Like I said, no unusual moves. What do you want me to do? Send him out for a pizza?”

The Green Room, Wednesday, 03^h00

Grant and his wife, accompanying King Charles, Camilla Parker-Bowles and His Britannic Majesty’s Ambassador, walked along the long Entrance Hall, the sound of Liszt’s Hungarian Rhapsodies coming from a dozen violins still entertaining a hundred guests in the State Dining Room. The President’s head was fuzzy from Chateau Latour and his cheeks ached from hours of enforced smiling. By protocol, he led them to the elevator taking them up to the residence for a private talk.

An hour later Charles and Camilla, looking exhausted, were being escorted by Secret Service men to Blair House, across the road from No. 1651. Grant gave it another hour and then came back down by the stairs to the Entrance Hall. He turned through the colonnade into the Cross Hall. Adam-style chandeliers and bronze standard lamps threw a warm glow on to the marble walls. Images of past presidents looked down at him. The violins were now silent. Somewhere three chimes of a clock cut into the stillness.

A door was ajar and he turned into the Green Room. Logs crackled in the fireplace, and a whiff of woodsmoke unexpectedly evoked a distant memory: a camp fire, sausages sizzling on a stick, smoke stinging his eyes, young men and women laughing. But before he could place the image in time, it had gone forever.

The Secretary of Defense, Nathan Bellarmine, was sprawled in a Federal-period chintz armchair at the fire. He had smooth, black hair, was slightly balding, and wore a dark three-piece suit. The dark waistcoat and Brylcreemed hair made him look slightly like a snooker player.

Occupying the chair at the other side of the fireplace was a small, hook-nosed, middle-aged man with white hair and eyes like dark pebbles: this was Arnold Cresak, the President’s National Security Adviser and a long-standing confidant.

The third man in the room was Hooper, sitting upright on a hard-backed chair, underneath Durrie’s nostalgic Farmyard in Winter. There were dark shadows under the soldier’s eyes. Grant waved them down as they began to rise, tossed his dinner jacket on to the carpeted floor and himself sank with a sigh into deep upholstery.

“Is the room clean?”

Cresak nodded. “It’s been swept.”

The President loosened his black tie. “I don’t like this early hours stuff, but what can we do? What are we doing?”

Bellarmine said: “I informed the British Prime Minister, and the Presidents of France and Germany, as you instructed. They sent us a couple of specialists Monday morning. I now have a team of seven trying to locate the asteroid. They’re being run by a Colonel Noordhof, who’s with USAF Space Command. I assigned him to 50 Wing, Falcon Colorado. Special Projects, which covers no end of sin.”

“Look, one whisper and we’re fried. Who are these seven samurai?”

“We have McNally, the NASA Administrator. The rest are top scientists, for example Shafer, the CalTech genius.”

“Shafer. The hippie scientist?”

Bellarmine said: “With two Nobel Prizes. He was on the cover of Time last month.”

“I don’t trust these superbrains: you don’t know what they’re really thinking. And what are we doing with Europeans on the team? That sounds to me like a couple of loose cannon.”

“We want the top people whoever they are. We’re in a life-or-death situation here.”

“They know the timescale we’re working to?”

Bellarmine nodded. “Consensus is the chances of success are very slim.”

The President held the palms of his hands towards the fire. “Sam, where in your opinion will the Russians hit us?”

“Kansas. First, they maximize their chance of hitting land. Second, they get Omaha, Cheyenne Peak and the revamped silos. If you believe this Sacheverell they’ll roast the States in less time than it takes to roast a chicken.”

“Kansas is a reasonable guess,” said Cresak. “But so is California. Maybe they’re going for our economic base. They don’t even care if they miss because a Pacific splash would submerge the West Coast.”

“And an Atlantic one would decapitate us,” said Hooper. “But who cares? We’re dead wherever it hits.”

“Okay.” Grant took a deep breath and visibly tensed. He looked like a man about to jump off a cliff. “Now say we don’t find Nemesis in time.”

Hooper said, “Sir, in that case the parameters define a very narrow envelope.”

“Sam, I’m a tired old man. If you mean we have limited options just say so.”

“We have to assume the worst-case situation.”

“Which is?”

“A blue sky impact. The asteroid comes in from daylight. The first we know about it is when it hits the upper atmosphere at sixty thousand miles an hour and we get a two-second warning.”

“Excuse me, but did you say a two-second warning?”

“Yes sir. Two seconds.”

“As His Royal Majesty expressed it to me, in his very British way, it would freeze the balls off a brass monkey in here.” The President poked at the fire and threw in a couple of logs. “Anyone want a hot chocolate?” Cresak leaned over to a work table next to the fireplace, pulled a telephone from a drawer and muttered an order.

“Now in those two seconds,” Hooper continued, “while it’s punching our air away, it seems it will also generate a massive electric current overhead. So it screws up our C-cubed systems.”

“I thought we had fibre-optic cables from here to Omaha,” the President said.

“A few, not a complete network. The real trouble is, the optical links still need electronic relays to boost the signal every so many miles. If the EMP zaps the relays, then the optical links go dead. Of course our satellite links collapse and we get cut off, isolated from everything at the critical moment.”

“Well now that’s just dandy. A few thousand engineers spend a few gigabucks of public money trying to fix it so we maintain integrity of command while the nukes are falling, only when it comes to the crunch you tell me what we really need are smoke signals.”

Hooper remained impassive. “The links might survive through a nuclear war, Chief, but the asteroid, now that’s a new ballgame.”

Bellarmine said, “So we lose contact with our counter-strike forces at the moment of atmospheric entry, and impact takes place two seconds later?” The Chairman of the Joint Chiefs of Staff nodded.

“I like your technique, Nathan,” Grant said, turning his palms once again towards the rising flames. “I like the casual way you slipped the word counterstrike into the conversation.”

An elderly man, wearing a dark blazer with the presidential seal on the breast pocket, came in, followed by a young maid. A table was set up with four steaming mugs. They left without a word.

Bellarmine turned to Hooper. “Could we counterstrike?”

The soldier shook his head. “Not effectively, Mister Secretary. When Nemesis cuts loose we’ll turn into a snake without a head. Even at Defcon One we couldn’t contact our silos, and our bombers would be torn to bits even if we got them aloft.”

“We still have our submarines,” Bellarmine said.

“How do we contact them? VLF, blue-green lasers and ELF. Very Low Frequency needs a wire a kilometre long trailed behind a TACAMO bomber. But all our command posts would be overwhelmed even before we contacted the bomber. The blue-green lasers beam down from the ORICS satellites. But”—Hooper checked off the points with his fingers—“One: the subs and satellites have to be in the right positions. Two: you have Kansas up there in the stratosphere giving us an umbrella of red-hot ash over the States. Three: you have an ionosphere gone crazy. So the signals don’t get up to our satellites in the first place.”

“And ELF?”

“We use a forty-mile antenna buried under Wisconsin. The radio pulses vibrate the whole Laurentian Shield. The vibration can be picked up from anywhere on Earth.”

Grant grunted. “So? That’s Nemesis-proof.”

“We still have to be alive to send messages.”

Bellarmine said, “Not necessarily. If we keep broadcasting Condition Red with the ELF, and other communications channels break down, standing orders are for submarine commanders to launch their nuclear weapons.”

The soldier leaned forward intently and said, “There’s a problem with that.”

“You may as well lay it on, Sam,” said the President.

“If we launch missiles they’ll run into Kansas on the way up and disintegrate. It’s like Brilliant Pebbles in reverse, a sort of natural Star Wars destroying our own counterstrike. Anyway, our submarine fleet carries only a small fraction of our megatonnage. Even if we get off a few Tridents the new ABM rings round Moscow, Kiev, Leningrad and so on could handle them. Mister President, it’s simple. If they get Nemesis in first our capacity to respond is smashed. Russia will incur acceptable losses, but we’ll be dead and gone.”

The President sighed. “Okay Nathan, get it off your chest. What are our options?”

“They’re stark. We can accept the annihilation of America and do nothing about it. We can wait for the impact and then try to hit back with our offensive capability smashed. Or we can beat them to the punch. Launch a nuclear strike now.”

“Uhuh.”

The President closed his eyes. Hooper wondered what thoughts were running through the old man’s head. The soldier said, “Only the third option has military credibility.”

A surge of fear suddenly went through Cresak’s nervous system like an electric shock. It was more than the fact that the unimaginable prospect of a nuclear war had entered the discussion; it was the fact that it had slipped in, by stealth, almost without conscious reasoning. “Crap,” he said, his voice unsteady. “The Russians would hit back. Then Nemesis would come in and finish off whatever was left of us.”

“The time for the Major Attack Option has never been better,” Bellarmine said. “They don’t expect it, their political system’s in chaos, and we have a dozen Alpha lasers in orbit to handle any Russian missiles that do get launched.”

“You’re insane,” said Cresak. “What about Carter’s PD-59? They could survive a strike long enough to obliterate us.”

“Nuclear war is winnable,” said Hooper emphatically. The situation has moved on since McNamara and Carter; we have the Alpha shields now. The winner is the one who hits first. Central Command computers show that a first strike will be decisive and that’s why our command and control systems are geared for a first-strike capability. We’ve always known that a second strike, one under attack, would fail utterly. Sir, we’ll never get another chance like this.”

“This is lunacy,” said the National Security Adviser. His voice was shaky but determined. He ticked the points off with his fingers, one by one. “The Russians kept their C3 system intact through all the political upheavals. Even with SALT and START they still have seven thousand ICBMs and a thousand submarine-launched missiles. They have two thousand bomb-proof bunkers to protect their top leadership. The situation has changed in Russia too. They’ve now got a streamlined chain of command, straight from their General Staff to their missile units. The new leadership have thrown away the old safeguards. They’ve obtained the unlock codes from the old KGB. The political officers have long gone from the system. They’ve taken away the electromechanical switches for sealing bomb doors.”

“Get to the point, Arnold. What are you driving at?” asked the President.

“Sir, they could respond in seconds. And if even a handful of their Sawflies got through, America would be finished.”

“Hell, Arnold, we can handle it,” Hooper said. “The Alpha lasers. And the leadership would be fried before they even reached their bunkers.”

The President sipped at his chocolate. It was too sweet. “What’s the modern view on nuclear winter?” he asked.

Hooper pulled a thin blue document from a battered briefcase at the side of his chair. “Our climate modellers have looked at all sorts of smoke injection scenarios. Mostly they darken the sun for about three months and could wipe out agriculture in the growing season. That’s another reason for an early strike, to let the sky clear by July.”

Grant said, “Sam, let’s not get too excited. There may not even be an asteroid. All we have is a string of circumstantial evidence that Heilbron has woven into a pattern. We can’t go levelling the planet just because the DCI has an overactive imagination.”

“With respect, sir,” Bellarmine insisted, “if there is an asteroid, chances are the first we know of it is when it hits, by which time we’re too late for an effective counterstrike. The only realistic option is Number Three.”

“I believe we’re seeing a sort of collective insanity here,” Cresak said, his fear betraying itself in his voice.

“Okay, let’s get down to basics,” said Grant. “What’s the strategic purpose of your third option, Sam?”

Hooper put down his mug of chocolate. His face showed real bafflement. “I must be missing something, sir.”

“What purpose is served by destroying Russia?”

“Retaliation,” said Hooper, the bafflement giving way to incredulity.

Bellarmine sensed something. He said, “Mister President. It’s been the official policy of every administration since World War Two that a Russian attack on mainland America will be met with the Major Attack Option.”

“Public policy, yes,” Grant replied. “And you know damn well our true policy is that if the diplomatic game ever gets hot we hit first. Hooper’s right. It’s the only chance of winning a nuclear exchange.”

“So!” Bellarmine raised his hands in an Italian-like gesture. “For fifty years mutual assured destruction has kept the West safe. What’s the difference between this asteroid thing and a big missile attack? The logic’s identical. We play it out.”

“Why?”

Bellarmine stayed silent. His expression was an exercise in suppressed bewilderment and outrage.

Cresak drove the point home. “I guess maybe the Chief thinks it’s pointless. Two big dust bowls instead of one.”

Bellarmine said, “Arnold, your jaw has got disengaged from your brain. Responsibility for the Russian people lies with their leadership, not with us. Our policy has been spelled out, clear as crystal, ever since World War Two. We serve future generations better by following through than by just backing off when the chips are down. The lesson will be remembered for a thousand years.”

“No doubt the cave dwellers for the next thousand years will be grateful for the lesson,” Cresak replied, his voice heavy with sarcasm. “And the two hundred million innocent people you burn will see the point too. We don’t seem to have progressed since the Salem witches.”

“Sure!” Bellarmine snarled. “Our ancestors thought they were doing right and they got it wrong. And if we get entangled in moral problems now we’ll get it just as wrong as they did. This is the White House, not a department of moral philosophy. Our business is to respond, according to publicly laid-down policy, to circumstances imposed on us by the Russians.”

“It’s getting hot in here,” said the President.

Hooper said, “Look. We’re under attack, so we defend. Period. Like any country, man or creature since time began. The only live issues are targeting policy and battle management.”

“What targets do you have in mind, Sam?”

“I’ve arranged a murder session with JSTPS in Offutt at twelve hundred hours. You’ll have our prepared options within forty-eight hours. The target sets will depend on whether we launch under attack or go for pre-emption. Mister President, I’m pushing for pre-emption. We have to finish this East — West thing once and for all. The prime target will be Russia but we should also take out Armenia, Belorussia, Moldavia, Kazakhstan, Georgia, Uzbekistan, Tajikistan and Estonia. We may also want to think about Cuba, Vietnam and China while we’re about it. I’m thinking of updating the old SIOP-5D list.”

Grant peered into Hooper’s eyes. The soldier stared unflinchingly back. “Some shopping list,” the President said. “What, specifically, do you mean by take out?”

“I mean destroy all nuclear and conventional military forces, the military and political leadership, the major economic and industrial centres, and all cities with more than 25,000 population.”

“LeMay would have been proud of you, Sam. Why China?”

“We’ll be so weak after Nemesis that we can’t afford to leave potential enemies around. Mister President, I want your unconditional assurance on this matter. That in the event of an asteroid strike on America becoming a proven eventuality, you will order a retaliatory counterstrike.”

A log collapsed in the fire, sending a little shower of sparks up the chimney. Grant lowered his head, strumming his fingers lightly on his knee. The others stared at him, frozen like models from a tableau in a wax museum. Thirty seconds passed, each one a century long.

“At this moment of time I will give no such assurance.”

“I don’t believe I’m hearing this,” said Bellarmine. His tone was aggressive. “Massive retaliation has been the backbone of our defence posture for generations, endorsed by successive administrations. It can’t be capriciously set aside by one individual. Not even a President. Your first duty is the defence of America. If you fail in that, you fail in your duty as President of these United States.”

“Why thank you, Nathan, a homily on my duty as President is just what I need at this time of night.” President Grant stretched and yawned. “Well, I’ve enjoyed our little fireside chat. Could this thing hit tonight?”

“Unlikely. Of course we don’t know for sure.” Bellarmine was trembling with anger.

“What’s the warning time for a night impact?”

“We think ten to forty minutes, sir,” said the Chief of Staffs.

“Better than two seconds. Nathan, Arnold, I want you guys to come up with a joint memorandum on the policy options facing us on the assumption that Nathan’s team fails to identify Nemesis or can’t find any way to stop it. I want it in time for the extraordinary NSC meeting on Friday midnight.”

The President stared into the fire for some moments. Then he seemed to come to a decision. “We must keep our options open. I’m prepared to go some way with you, Sam. Increase our state of alert. Let’s go to Orange.”

Bellarmine nodded his agreement. “Sam, upgrade to Defcon 3 worldwide.”

The President stood up, and the men followed him into the hallway. “Oh by the way, gentlemen. Merry Christmas.” He made his way towards the secret stairway at the East Hall which would take him to the third floor and the Family Quarters, an old man longing for rest. Cresak went back into the Green Room and sat down, staring into the leaping flames. Hooper went off, heading for the back exit. Bellarmine paced up and down the long corridor for ten minutes, feeling stunned. Then he too went towards the rear of the building.

The air was sharp and cold, and there was a bitter breeze. The grounds were white with a foot of freshly fallen snow. A pine tree, its coloured lights swaying in the breeze, stood on the central lawn. Hooper, wearing a long army coat and a white scarf, was standing on the steps of the North Portico, flapping his arms against his sides. A few Secret Service men hovered in the background; they looked frozen stiff.

“Was I hearing right in there, Mister Secretary?” asked Hooper, his breath misty in the freezing air.

“Give me a lift,” said Bellarmine grimly. “We have to talk.”

“Too damn right. Where you heading?”

“Virginia.”

“Big place. Defcon Three can wait awhile.”

Hooper pressed a button and a glass partition slid up, cutting them off from the army driver. The general lit up a small cigar and its tip glowed red in the dark.

“You have to smoke these disgusting things?” Bellarmine asked.

“Privilege of rank,” Hooper replied, exhaling a dense smoke cloud. “Anyway, these disgusting things just happen to be fine Havana cheroots. Heilbron gets his field people to bring them in from Cuba.”

They passed on to the Ellipse. A group of youths stood shivering, scarves round their necks and woollen hats pulled down almost to their eyes. Bellarmine just caught the words “Say No To Torture” on a placard as the beam of light from the car swept across it.

“A pacifist for a president, at a time like this,” said Hooper. Now the headlights were picking up the broad swathe of Constitution Avenue.

“What do you want — Rambo?”

“Rambo we could handle.” Hooper inhaled the cigar smoke. “Nathan, we can’t let it happen.”

“Meaning?”

“You know what I mean.”

The car was driving past the Vietnam War Memorial. Beyond it the rotunda of the Lincoln Memorial was lit up with a ghostly glow. Bellarmine began to feel his lungs outlined by cigar smoke. “Grant’s mother was a Quaker,” he said. “Can it be relevant?”

Hooper took another big draw. “No pacifist should hold the office of President.”

“Sam, talk like that is highly dangerous.”

“Uhuh.”

The car crossed the Woodrow Wilson Memorial bridge; little ice floes on the Potomac reflected orange in the street lights. Snow, compacted by earlier traffic, covered the Beltway. The driver pulled out to pass a truck and grit pattered briefly on the windscreen.

After twenty minutes, marked by a stunned silence and a rapidly increasing smoke density, a sign said Langley and the car turned off the highway. They drove along a tunnel of light. The CIA Headquarters was lit up by yellow spotlights. It reminded Bellarmine of a Soviet housing complex, all massive concrete blocks and narrow windows. The driver stopped near the main entrance.

Hooper repeated, grimly, “No pacifist has the right to hold the office of President.”

“So you said.” The driver opened the door and Bellarmine stepped out into the icy air. After Hooper’s smoke-filled car, the fragrance of the night was delicious. While the driver held the door, the Secretary of Defense turned back and leaned in to the car. “The question is: what are we going to do about it?”

Eagle Peak, Wednesday

Webb rummaged in a cardboard box in the dormitory cupboard, and found a woollen hat to match the multi-coloured jumper. He pulled the hat on and headed for the kitchen, intending to make a hot chocolate before facing the chilly outside air once more. Shafer was staggering into the kitchen with a rabbit-sized boulder, coated with snow. Noordhof opened the door of the microwave cooker, and Shafer heaved the boulder in, setting the timer for five minutes.

Webb rattled a saucepan on to the cooker and added milk. “It won’t work,” he said, looking for a tin of hot chocolate in a cupboard stuffed with the detritus of past visiting observers.

“Mark’s idea,” said Shafer. “He’s just shown me a Newsweek article by Broadbent from some months back. Mark can’t confirm without clearance, which would take time, but listen to what this guy says.” He picked up the opened magazine from a kitchen work surface:

“In the euphoria of the First Cold War thaw, and with the easing of security in government laboratories around the States, previously tight-lipped administrators appeared to confirm what many academic scientists outside the system had long claimed: that Star Wars was a spectacular, and highly expensive, failure. A year of investigative reporting by our team, however, has turned up a different story.

“Blah blah blah. The guy goes on to say there was an element of disinformation in the ‘Star Wars Failed’ stuff. He says the Army have an array of antennae not too far from Albuquerque. They call it the Beta maser, and it’s arguably in contravention of the ABM Treaty. You’ll note that Mark isn’t contradicting me. Broadbent even says that on one experimental run the Beta maser destroyed a warhead they’d launched from Mid-Pacific, the moment it appeared over the horizon. So if the Beta exists maybe it could do something to the asteroid, but Mark has the right to remain silent, which right you’ll notice he’s exercising.”

Noordhof said nothing, but he was looking pleased with himself.

“That is one impressive zap,” said Kowalski, looking up from a sheaf of papers. “Assuming there’s truth in the story, maybe it’s the answer to our prayers. Colonel, you must cut through the tape. Get us clearance for this stuff right away.”

“No need,” said Shafer. “We can work out what we need from the article. If these guys can really vaporize a warhead at say five thousand miles’ range, it means they penetrate the ablation shield and raise the missile’s internal temperature to a thousand degrees within two or three seconds. So let’s see how hot this rock gets in five minutes with a miserable kilowatt and use it to get its thermal conductivity.”

The milk was coming to the boil. Webb pummelled hard-caked chocolate powder in a tin. “It won’t work,” he repeated, stirring in the chocolate. Noordhof scowled.

The microwave oven pinged and Shafer put his hand on the rock. “Warm to the touch. It went in at zero Centigrade so it’s gone through thirty degrees in five minutes, say five or six degrees a minute.”

Webb took a sip at the hot chocolate and sighed happily. “I expect your rock is still cold inside.”

Shafer nodded. “So is Nemesis. And if it’s rock the maser heat will get conducted down quickly. Okay, say a kilowatt gives us half a degree a second on this little stone, and the Beta maser heats a target at five hundred degrees a second.” The Nobel man counted fingers. “Hey, these guys must be beaming one megawatt per square metre at five thousand miles’ range, can you believe that?”

Noordhof radiated happiness. “Nothing could withstand it. And laser beams don’t spread out with distance. We’ll ablate Nemesis clean out of the solar system, punch boulders off it. Hey, who needs the eggheads? I thought of this all by myself.”

Shafer shook his head sorrowfully. “No dice, Mark. Laser beams do spread out. Imagine two mirrors at the ends of a tube, reflecting light back and forth, one of the mirrors with a pinhole. You generate fluorescence inside the tube, and the light reflects and gets pumped up to huge intensity. The only light that makes it out through the hole has travelled the full length of the beam, but there’s still an angular spread. It’s the wavelength of the light divided by the diameter of the gun.”

“Maybe it’s a very big gun,” Noordhof interrupted, “Giving a very small dispersion.”

“You have the Alpha lasers in orbit. They’re hydrogen-fluoride, emitting at 2.7 microns. I guess their peak power can reach ten or twenty megawatts, but they can’t be more than a few metres across.”

Noordhof waved the magazine at Shafer. His tone was a mixture of triumph and desperation. “But this guy is talking about masers, not lasers. Everything is much bigger at radio wavelengths.”

Shafer shook his head again. “No way can you guys be hiding an array more than ten kilometres across, not even in the New Mexico desert. Ergo, if you’re beaming centimetre waves the angular spread is at least one part in a million.”

Noordhof spread his hands. “So? Nothing!”

“Nothing at five thousand miles. But if you catch Nemesis a million kilometres away the centimetre wave beam is spread out over one kilometre, the whole size of the asteroid. With attenuation like that you couldn’t boil an egg. Uncertainties in thermal conductivity or internal temperature will make no difference. I’m sorry Mark, but your top secret, Darth Vader, gigabuck, Space Dominance, missile-zapping Star Wars supermaser is as useful as a peashooter. We’re back to nukes.”

Webb couldn’t resist it: “I told you it wouldn’t work.”

“Where the hell do you think you’re going, Webb? Are you looking for Nemesis in the woods?”

“I’m looking for inspiration, Colonel. From the performance I’ve seen here, I’m more likely to find it with the squirrels.”

Noordhof opened the microwave door angrily. “Well, you might take the friggin’ rock out with you.”

Shafer was still laughing when Webb left the building.

At the far end of the little car park there was a gap in the trees which, on closer examination, turned out to be the beginning of a natural path. It was close to a cluster of garbage bins and Webb suspected that it might be a raiding route for some animals. He took off along it, and found that the path skirted the foot of Eagle Peak, rising gently as it went, with the cliff easily visible to the left through the heavy ponderosa trees. After about twenty minutes, far beyond Noordhof’s hundred-metre limit, he turned off to the base of the cliff, brushed the powdery snow off a broad boulder and sat down on it. There was the merest hint of cable rising above the trees about a mile back; otherwise there were no signs of human artefact. For the first time since he had been snatched from another snow-covered mountain, halfway round the planet, Webb had time to stop and think.

A last-minute asteroid deflection was a crass thing, a hefty punch with a barely controllable outcome. A punch on the nose, slowing Nemesis down long enough for the Earth to slip past, was more effective than a sideways swipe. But as the warning time dwindled so the punch became increasingly desperate, to the point where either you risked breaking the asteroid into a lethal swarm or you could do nothing to ward it off. Just which side of the threshold they were on they wouldn’t know until they had identified Nemesis.

The Russians, however, had had a different problem: that of precision. Probably, Webb thought, they had used a standoff explosion of a few megatons to give a crude impulse of a metre a second or thereabouts. The bigger the bomb the more potential asteroid weapons were available, and the Russians had hundred-megatonners in their arsenal. For every asteroid liable to hit the Earth they would have a hundred or more potential weapons in the form of near-missers.

But after that they would have had to finesse. A hit within a few hundred miles — or even a thousand miles — of Kansas would be adequate to obliterate the States. But a thousand miles is precision! After the initial big explosion, possibly years in the past, they would have required a series of small shepherding explosions, maybe little more than Hiroshimas, to guide the asteroid in.

All of which implied a fair amount of clandestine space activity, maybe using the Phobos or Venera series as a cover. Leclerc’s knowledge of past Russian space trips was the key.

There was a movement in the woods. A couple of crows were cautiously dropping from branch to branch about fifty yards away. And something small was scurrying through the trees. A white fox popped its head up and looked at Webb curiously. In a flash of inspiration, Webb suddenly realized that there was another key. He jumped up and the fox and crows disappeared.

In passing he looked in the kitchen and the common room, and knocked on Leclerc’s door. He threw off the hat and jumper. Back down to the conference room. “Where’s André?” he asked. Judy looked up briefly from a terminal and shrugged.

Webb picked up a pile of blank paper and made his way to the common room. It was empty. Warm afternoon sunlight was streaming in through the panoramic window. A green leather chair had a worn, comfortable look about it. He settled in. The sun was warm on his thighs and a light scented breeze was coming in through the window.

In some anonymous galaxy near the boundaries of space and time, two neutron stars had collided. With collision velocities close to the speed of light, the stars had annihilated their own matter, transforming it into a flash of radiation of incomprehensible intensity. Before even the Sun and Earth had formed, the radiation was spreading out through the Universe as a thin, expanding spherical shell. And then came the Sun and planets, and life evolved in the oceans, and then the reptiles had crawled on to land and the big archosaurs had ruled the Earth until the solar system entered a spiral arm, whence they had died in a massive bombardment of dust and impacts. It was an episode which had left the mammals and the insects, in their turn, to inherit the Earth. By the time the first primates had appeared the gamma rays were invading the Local Supercluster of galaxies; when homo sapiens was learning to carve on rocks the radiation was sweeping through the cave man’s own galaxy; and finally, at the very instant the apes had learned how to throw little metal machines around the Earth, the shell had momentarily rushed through the solar system, on its endless voyage to other stars and other galaxies.

But as the energetic photons swept past, a tiny handful had been picked up by the satellites which the apes had just developed; a millisecond gamma ray burst was duly recorded; theoreticians speculated; papers were written and debated; and arriving from cataclysms scattered through the cosmic wilderness, other gamma ray bursts were being picked up, recorded, discussed and debated, and catalogued.

And this was Webb’s problem. The Universe snaps and crackles across the whole electromagnetic spectrum. Neutron stars collide; massive stars run out of thermonuclear fuel, collapse and then destroy themselves in a gigantic thermonuclear explosion; red dwarfs dump their atmospheres on to white dwarf companions; relativistic jets squirt from the nuclei of galaxies and stars. Somewhere in this tremendous background of noise was a local event. A sprinkling of X-rays, perhaps, from an illegal nuclear explosion; or a brief flash of light in the sky. An explosion on Nemesis would throw hundreds of thousands of tons of debris into space. Maybe ice, maybe boulders, but surely dust. A cone of dust, fanning out into space and sparkling in the sunlight; a beacon in the dark interplanetary void.

Amongst the thousands of X-ray flashes picked up by CHANDRA, there might just be a signature of a different sort. Or maybe even the wide-angle camera on SPITZER had picked up a fading infrared glow as the debris from the crater dispersed into the zodiacal dust cloud. Or the Hubble had picked up something.

The first thing was to calculate the signatures that would discriminate between natural astrophysical processes and the effects of a bomb. He would have to investigate a wide range of physical processes. Maybe the hefty thump of 14 MeV neutrons from the thermonuclear fireball yielded a characteristic signature; or the timescale for dispersal of the dust yielded a light curve unlike that from any eclipsing binary. Webb sighed and pulled over a coffee table with a dish of Liquorice Allsorts and jelly babies. It was going to be a long session.

Lunch came and went unnoticed. Colleagues came and went through the common room; Webb was not disturbed. The level of the sweets in the dish next to Webb slowly declined. Around six in the evening Judy went into the kitchen and the smell of curry soon wafted around the common room. Kowalski appeared shortly afterwards, dressed in his Eskimo suit, and then Shafer and Noordhof emerged from the conference room, arguing about something; their voices changed to a low murmur but Webb appeared not to notice. Someone handed Webb a coffee and switched on a lamp. The sun set. Papers scrawled with formulae piled up on the coffee table. The sweets disappeared.

Around midnight Webb completed his calculations: he had his electromagnetic signatures. The best bet had turned out to be the simplest: an unexplained flash of light, seen in the telescope of some amateur comet hunter somewhere on the planet. It might just have been recorded in the IAU Circulars, the electronic clearing house for transient and unexpected astronomical phenomena.

He looked at his watch in surprise, and realized that he hadn’t eaten. There was a plate of chicken curry, boiled rice and a Nan bread in the microwave oven. He fired it up, was tempted by the can of Red Stripe on the kitchen table but decided against it. He gulped the food down and then went straight through to the conference room along the now darkened corridor. The room too was dark apart from the light from the terminals. Judy and Sacheverell were sitting at terminals. Starfields were drifting across their vision.

“How did the briefing go, Herb?” Webb asked.

“No sweat,” Sacheverell said without looking up.

“We’re filtering out the main belters automatically,” Shafer said, “otherwise we’d snarl up.”

“And between Spacewatch, Flagstaff and ourselves we’ve found thirty Earth-crossers already,” Judy said. “Thirty-one,” she added as the terminal beeped.

“How are you handling them?” Webb asked.

“No sweat.” Sacheverell again. “The Teraflop is coping with everything we throw at it. We come back to the new ones after an hour or two. Look.” He pressed a terminal key and the single picture was replaced with a dozen small squares, each centred on a bright spot. The little pictures, like frames from a movie, showed clearly that the spot was drifting against the stellar background. “Usually they’ve moved several pixels, sometimes dozens. We might not get an orbit but if it has a strong tangential drift we know it’s not an immediate hazard.”

“Where are you searching?” Webb asked Shafer.

“Where you expect to find them,” Sacheverell interrupted. “In and around the ecliptic plane. I hope you’re not going to start on crap about high inclination dark Halleys.”

“They’re not practical weapons, Herb. Anyway it doesn’t matter where you look, you haven’t a hope.”

Sacheverell looked up from the screen. “Hey, we finally agree on something.”

“But don’t tell the Colonel what we’re agreed on. He’s already had a bad day.” Webb sat down at a spare terminal and quickly typed into the Internet. Once into the IAU Circulars, he began to read every one, starting from the most recent and going back through time. Each unexplained flash of light, each gamma ray burst, each surge of X-rays reported in the sky, had to be matched against the theoretical expectations he now carried in his head. It was a slow, painstaking, tedious grind.

Around 3 a.m. Judy disappeared, and half an hour thereafter Webb too felt he had to take a break. He wandered across the darkened hallway to the dimly lit common room and flopped down in an armchair. The urge to sleep was almost irresistible. There was a smell of perfume. “Hey, Mister!” Judy said in a soft voice. “Not even Superman could keep that up.” Startled, he saw that Judy was in the armchair opposite. In the dim light he could just make out that she was wearing a long green dressing gown; her hair was tousled and her blue eyes were strained with tiredness.

Without thinking, he said, “What’s a nice girl like you doing in nuclear weapons? You should be having babies.”

She bristled, but then burst out laughing when she detected Webb’s sly grin. “Webb the sexist! I’m sure. I’m in nukes for the same reason you’re in astrophysics, Oliver. I love the subject.”

He felt unable to think. When he spoke, the words were slurred with exhaustion. “So the lady loves nukes. I still can’t think why.”

In spite of her exhaustion, enthusiasm came through in her voice. “Think of a nuclear fireball in the first microsecond of its formation. The power to devastate a small country in something the size of a beachball. There’s a wonderful purity about a nuke, Ollie. It sweeps away everything; even elements are transmuted. It’s as near as we can get on Earth to the Creation.”

“You make getting nuked sound like a religious experience,” Webb replied, hardly caring what he said. “But you want to destroy things, and I want to understand them. I happen to think we were created from something like your fireball.”

“The Big Bang?” she asked.

Webb shook his head. “The nucleus of the Galaxy. This is something that nobody in their right mind believes. But I still say women are for childbearing. They’re supposed to create, not destroy.”

“All females defend their young. Having had our babies we need to protect them. I do create, Oliver, I create peace. Is that not a noble pursuit in a barbaric world? You have the nerve to sit there and bask in the purity of your subject, with Nemesis on the way in? We can only manage miserable ten-megaton firecrackers, but you? You go cosmic.”

“I also love dogs,” said Webb.

“I prefer cats. And cars. I can strip a Pontiac to its gudgeon pins and reassemble it in a day.”

Webb said, “You can strip me to my gudgeon pins any day. I’m a fair cook, and I climb mountains.” He thought, This conversation is getting surreal.

She shook her head. “I’d rather fly over them in my Piper. But maybe you can cook me a dinner some time.”

Webb’s skin tingled at the invitation and he thought, hell I must still be alive. “Which brings me to boyfriends. Got any?”

“Lots of them, all strictly platonic. So far I find nukes more interesting.”

“Are all nuclear physicists as beautiful as you?”

“Only the females.” She stretched her slim legs out on the coffee table between them, nudging papers aside with her bare feet. “What about you?”

“The ladies? I have an effect on them. But haven’t had time to explore the subject. I notice you paint your toenails, ma’am.”

“I hope you paint yours, Oliver. Otherwise we have nothing in common.”

Noordhof marched in and switched on a light. He took one look at the exhausted scientists, blinking in the light, and said, “You two. Get to bed before you collapse, and that’s an order. You’re no damn use in that state.”

Judy waved and more or less staggered towards the dormitory. Webb felt his way along the pitch black corridor and stepped outside. The snowy landscape glowed softly in the light of the Milky Way and the stars. He breathed in the scented air, letting his eyes, strained by hours of terminal-staring, adapt to the dark.

The IAU circulars had revealed nothing.

Mars was high in the south, a bright red, unwinking beacon which, in a couple of hundred years, would hold a teeming human population, a population which would marvel at the havoc their ancestors had wreaked on the beautiful blue planet. A few lights were scattered over the desert far below.

He strolled on to the road which, that morning, he had pounded down with Leclerc and Whaler. Some animal screamed in the distance, a prolonged scream which set Webb’s nerves jangling.

The next step would be the SPITZER catalogue and maybe some ultraviolet stuff, maybe even going as far back as the IUE which had closed down in 1997. But he knew it wouldn’t wash; these were shots so long they had to be a last resort.

Something.

Something; a new idea trying to climb out from his subconscious. But what?

The animal screamed again, closer; or was it another animal? And what makes an animal scream in the night?

Suddenly cold and nervous, Webb turned back towards the observatory. He was asleep within two minutes of collapsing into bed.

Webb was in the cloister of a monastery, hiding behind a potted palm. In the cobbled central courtyard, hooded monks were building a scaffold. The carpenter, a monk with Noordhof’s face, had a row of six-inch nails protruding from his grinning mouth. They were hammering the scaffold together at superhuman speed, only the scaffold turned out to be a big wooden cross and the hammering was overwhelming and it transformed into an urgent tapping at Webb’s door, dragging him from his lurid subconscious world into the real one. The dream faded and Webb thought that perhaps Judy had overdone the chillies.

“Oliver!”

Feeling drugged, the astronomer heaved himself out of bed, put on a robe and opened the door, blinking in the subdued light of the hallway. Judy; still in her dressing gown, still with tousled blonde hair and tired, strained eyes. “Kenneth called. They think they’ve found something. He’s gone up in the cable car with Herb.”

Webb followed Judy down to the darkened conference room. Noordhof and Shafer were clustered round a terminal, the light from the screen giving a blue tinge to their faces. Shafer was in boxer shorts and singlet, and his hair was drawn back into a ponytail by an elastic band. Noordhof was fully dressed. The colonel moved aside and Webb looked at a hundred thousand stars. A wisp of nebulosity crossed the bottom of the screen, probably a remnant from some past stellar cataclysm. The starfield wasn’t drifting: someone had set the telescope for a long exposure.

“You see the little triangle of stars near the middle? The top one has moved.” Judy said.

“What’s its angular rate?” Webb asked.

“Extremely low,” Shafer said. “About a pixel an hour.”

“So it’s either heading away from us or straight at us.”

“It’s coming at us,” Shafer informed Webb. “It’s slowly brightening.”

“Have you any orbit at all?”

The physicist pointed to an adjacent terminal. The centre of the screen showed a coin-sized disc. A series of near-parallel lines criss-crossed the screen, the longer ones going from edge to edge; each line passed through the centre of the disc. “This is one of Herb’s programmes. We’re projecting the two-sigma error ellipses on to the target plane.”

“Only you don’t have distance information so the ellipses come out like lines.”

“That’s the problem. You see they’ve been shrinking as the data accumulate, but they still pass through the Earth. Collision is a definite possibility.”

“I agree, Willy, but so is a miss. These are still long lines. We need an accurate orbit and we’re not going to get that with a one-hour time base.”

“You said it yourself, Ollie. The Earth’s gravity pulls things in when they get close. In the last stages these lines will shrink to a point.”

“What are the chances, Ollie? Is this Nemesis?” Noordhof asked anxiously.

“At a minimum, it’s going to be a very close encounter.”

“What does that mean? Do I wake the President or not?”

Another elongated ellipse suddenly appeared on the screen, shorter than its predecessors. Its centre still passed firmly through the coin-sized Earth.

“This is it, right?”

Webb lowered his head in thought. “Mark, we’re not going to answer your question with the orbital dynamics to hand.”

“But we can’t wait. Not if this is the big one.”

Webb asked, “Do we have brightness information?”

Shafer nodded. “Herb says its magnitude has gone from twenty-one point five to twenty-one point two in the last hour.”

“I thought we weren’t looking fainter than seventeen?”

Shafer shrugged. “Mark ordered it. He’s still fixated with Baby Bears.”

Noordhof said, “Screw you, Willy. I made the right call and there’s the living proof.”

“Kenneth and Herb are trying to get its spectrum with the ninety-four-inch,” Judy volunteered.

Webb said, “At m equals 21? Full marks for effort. Look, the orbital accuracy is horrendous but we might be able to use δm. Anyone got a calculator?” Shafer thrust one into Webb’s hand. “Point three magnitude change translates into a roughly thirty per cent brightening in the last hour.”

“Maybe it’s just a rotating brick,” Shafer suggested.

“Too much light change in too short a time. Chances are the bulk of it is due to its approach. With inverse square its distance from us has decreased by fifteen per cent in the last hour. A spectrum is pointless. It’ll be on us in seven or eight hours.”

Shafer said: “Jesus.” The tone sounded more like a sudden conversion to Christianity than an oath.

Noordhof had an unlit cigar between his fingers. “If this is Nemesis we’re dead. Is it Nemesis?”

“Willy’s point about rotation is partly right. We just don’t know the approach rate precisely enough to be sure.”

“Wonderful!” Noordhof snarled. He crushed the cigar and threw it to the floor.

“Let’s guess it’s approaching at twenty kilometres a second. In six hours that puts it”—Webb tapped buttons on the calculator—“Crikey. Less than half a million kilometres away. What’s the time?”

Noordhof looked at the big railway clock. “Four fifteen.”

“From the way you guys have been operating I guess Kenneth’s supernova telescope has picked this thing up near the meridian. We’re probably looking at an eighty per cent sunlit face rather than a night-time crescent.”

“Make this quick, Webb,” said Noordhof. “The White House are going to need every second we can give them.”

Webb crossed to the blackboard and used his sleeve to wipe a clear space. There was just enough light to scribble. “A one-kilometre carbonaceous asteroid has magnitude 18 at one AU. This thing is 0.003 AU away which with inverse square luminosity would make it a hundred thousand times brighter than that, size for size. Use the magnitude/brightness formula

Put m₂ 18 and L₁/L₂ 100,000. At that distance, a one-kilometre asteroid would have magnitude 5.5. You could see it with the naked eye.” Webb stabbed the air with a piece of chalk. “But this one is 20.5, fifteen magnitudes fainter. For every five mags you go down, you lose a factor of a hundred in brightness. Ten mags down gives it only one ten thousandth of the intrinsic luminosity of a one-kilometre asteroid, ditto the surface area. This beast is less than a hundredth of a kilometre in diameter. Hey, we can relax. It’s only ten metres across.”

Shafer laughed. “A glorified beachball!”

“Are you sure?” Noordhof wanted to know.

Webb nodded. “At the ninety-nine per cent level. Even if it hits it’ll just be a brilliant fireball in the sky. We get these all the time. Colonel, you’re a fool. You’ve thrown away priceless hours of observing time. Forget the Baby Bears.”

An expression close to terror crossed Noordhof’s face. “I was about to waken the President.” A collective outburst of laughter relieved the tension. Judy headed for the kitchen and started to fill the coffee percolator.

“By the way,” Webb asked, “Where’s André?”

“He’s not in his room,” Judy called through.

“And he’s not up top,” Noordhof said.

Shafer put his hand to his mouth. “Ollie, I haven’t seen Leclerc since lunchtime.”

Webb looked at Noordhof. “Mark, it’s been a bad day. First a blind alley with your laser. Then a false alarm with this beachball. And now it seems that one of your team has gone missing.”

The Tenerife Robot

Judy pulled her dressing gown lapels round her neck and made for the dormitory. Webb, swaying with tiredness, headed in the same direction.

“Where do you think you’re going, Webb?”

“I’d have thought that was obvious, boss.” Webb saluted ironically.

“I’ve given thought to your friend’s automated telescope. The one in Tenerife. You say you can work it from here?”

“I can work it from here. The instructions go to Scott’s Oxford terminal and get routed through. Anyone sniffing cables at Tenerife would believe the operator was in Oxford.”

“With an external phone line? And an open modem?”

“Yes, for direct access. But it’s password protected and I have the password.”

“And your friend?”

“Scott’s in Patras. His wife is Greek and they’re with her family over Christmas. I have an open invitation to use the robotic telescope until it’s properly commissioned.”

“So, with half a million megatons coming in, and a telescope sitting idle, your action plan is to fall asleep.”

“I was waiting for your authorization, remember? Are you telling me you’re getting over your paranoia?”

“I have to balance risks here. Go ahead with it.”

“The sun’s up over Tenerife by now, Mark, but I’ll check that I can access it from here. Meantime, Herb and Kenneth must be turning into icemen, trying to get the spectrum of your beachball. Why don’t you call them back down?”

Webb sat heavily down at the terminal Judy had been at. The chair was still warm. Another small ellipse had appeared on the screen, the disc representing the Earth still firmly inside it. By the time the bolide arrived the Pacific would be in darkness, and a brilliant shooting star would light up the night sky, to be seen only by the uncomprehending eyes of flying fish. He routed the picture over to an empty terminal, and typed in a file transfer protocol. Immediately, the terminal asked for his user-name and password. He gave these and a fresh window appeared on screen: he was now in effect sitting at his own computer in Wadham College. He asked for a second FTP to be opened up, the one linking him to the robotic telescope. Webb was asked for a PIN number. He supplied it and found himself in effect in Tenerife, at the console of Scott’s telescope, in little more time than it took to say Beam me up Scottie. The whole procedure had taken less than thirty seconds.

Webb could now use the mouse to control the movement of the telescope, little numbers at the top right hand of the screen giving the celestial co-ordinates at the centre of the starfield. The shutters of the telescope dome were closed in daylight hours, but he had confirmed that he could contact the telescope from here.

Then he switched to the external camera, mounted on a pillar about fifty yards from the main instrument.

The picture came through immediately. The camera was looking back at the telescope, whose silver dome was gleaming in the morning sunlight. He rotated the telescope dome and saw it swivel immediately. He scanned slowly, and the camera panned over the rocky foreground. A cluster of telescopes came into view, the massive William Herschel conspicuous amongst them. Someone was walking outside the big dome. He carried on scanning, and the camera picked up the tops of clouds further down the mountain; they were above the inversion layer, and the atmosphere was likely very dry. He pressed another button and temperature, pressure, humidity and prevailing wind at the site were displayed. Then he swung the camera over the Tenerife sky; it was cloudless. Everything was operating smoothly. Tonight he would use the robot to search for Atens. As the signal came in to Eagle Peak it would automatically be reproduced a few hundred miles away, at Albuquerque, and the Teraflop would interrogate each picture element on the screen, comparing it with a digitized star chart and the co-ordinates of known asteroids. Any discrepancy would be recorded as a flashing point on the terminal VDU.

The thing would be to get as close as he could to the horizon, close to the sun but before the dawn light flooded the CCDs. Experimentally, he typed in an altitude and azimuth. Again the telescope’s response was swift.

In fact, remarkably swift: there was something odd.

Webb felt his scalp prickling.

His exhaustion suddenly lifted. He typed in another celestial co-ordinate. He tried a third and a fourth, each one with the same amazingly fast response.

He took a surreptitious look around. Shafer was at a terminal, leaning back in his chair, arms flopped at his side. With his eyes half shut and mouth half open, and with his stubble and ponytail, he looked more like a moron in a gangster movie than one of the sharpest scientists on the planet. Noordhof was at the conference table reading some report. Both men seemed past the point of exhaustion. Quietly, Webb logged on to the Internet and navigated his way to an infrared satellite image of Europe and North Africa. The image was less than ten minutes old. Tenerife and La Palma were covered with cloud. No mountain tops protruded above them. And yet the Tenerife camera was showing a clear, sunny sky.

Slowly, a fact almost beyond comprehension sank into Webb’s mind.

The observations from the robot telescope were a fake.

Lake Pepsi

Wallis rolled one of the general’s Havana cheroots from one end of his mouth to the other, spat, and heaved again on the oars. Little whirlpools spun away from the boat and it lurched erratically forwards.

Wallis thought he might as well be rowing a corpse. The CJCS lay back, motionless, a hand trailing in the water. His small mouth gaped open and a strip of hairy stomach lay exposed between his Hawaiian tunic and the top of his trousers.

The corpse was calculating. From time to time Wallis thought he saw the fat man’s eyes briefly studying him from behind the reflecting sunglasses. They were about half a mile out from the shore, the general’s jeep a little splodge of fawn next to the jetty.

The lake, set in a ring of wooded hills, was like the caldera of some ancient volcano. A flock of snow geese flew in formation, honking high overhead, preferring the winter in Baja California to the one in Siberia: voting with their wings.

He needs an opening, Wallis decided. He said: “Quite a place you’ve got here, as they say in old movies.”

The corpse stirred. “Margaret’s,” said Hooper. The comment was unnecessary: his marriage into one of the wealthiest families in America, with both showbiz and dubious New York family connections, had long been a staple of tabloid gossip. “This particular land was bought on some killing with Pepsi futures. You’re practically rowing on the stuff. Foggy, feather your oars and stow your barnacles or whatever it is matelots do. Now we’re going to drink a little beer, catch a coupla fish and have ourselves a friendly little talk.”

The Chairman of the Joint Chiefs of Staff sat up and opened the lid of the wicker picnic basket. He moved aside a six-pack of Red Stripe and the small black briefcase which never left his side. He struggled with some fishing tackle; it looked new and the general gave the impression of a man who couldn’t tell a fly from a spinnaker. A little white worm wriggled in silent agony as a hook was thrust through it, and then it was whipped through the air into the water. The geese vanished behind Jacob’s Mountain and the honking faded away.

“Margaret likes her barbecues, good chance to meet people. Probably Teddy, the Clinton people and a few of her showbiz friends, maybe the Newmans. Oh, and some Mexican band. You may not want to come after you’ve heard me out.”

“General, I’ve long since deduced that I’m not here for the fishing.”

“Son, what you are here for will blow your mind apart. First I want to ask you a few questions. All on a hypothetical level, none of it’s for real, if you get my drift.”

“I get your drift.”

Hooper gave a half-smile. “Sure you do, you’re a bright boy. How come they call you Foggy?”

“It goes back to Parrot Island, sir. I guess I go around in a kind of haze.”

“Which haze doesn’t fool me. You’re bright enough to know that if you report this conversation I will deny that it ever took place. Talking about boys, how’s your one getting on? He’s on some sort of camping trip in Allegheny, ain’t he?”

Wallis’s heart gave a jump. It was a distinct thump in the chest. “Didn’t know you knew about it, sir,” he said casually. His son had arranged it with a teenage friend only the week before. Nobody outside the family circle had known about it.

“Real mountain man country up there. Straight out of Deliverance. You got balls letting your boy go out there. Still, I reckon they’ve got to find their own feet some time.” Below the sunglasses, Hooper’s mouth had formed into a prim smile, and the incredible fact dawned on Wallis that his commanding officer had issued a threat.

“General, why are we here?” Wallis threw his half-smoked cigar in the water with a nervous gesture. The atmosphere was suddenly tense.

“Nemesis.”

“The Martian scenario.”

“A tiny handful of people in America know about it. You’re one of them.”

“No doubt for good reason, sir.” Wallis waited, an unformed sense of dread washing over him.

“Colonel, in what circumstances would you commit treason?”

Wallis stared, aghast, but all he got was his own distorted image, bulbous in the fly’s eyes of his commanding officer’s sunglasses.

“Sir, the question is an insult. I don’t want this conversation to continue.”

“The honour of your country is at stake.”

“If you put it that way.” Wallis retreated into his shell, slipping into a formal, military-style tone. “As you well know, sir, my oath of allegiance calls on me to serve my country, and to obey the orders of my superior officers to the limits of my conscience. If there’s something in the book about treason I guess I missed it.”

Hooper’s eyes showed approval. “Sinews of an army, son. Without loyalty and discipline and obedience, sometimes even blind obedience, you don’t have an army, you have a rampaging horde. Trouble is, obedience is morally neutral — it serves all sorts of masters. But this man’s army is based on values. Cripes, the lettuce Margaret puts on my sandwiches. ’Kay, let’s start easy. Suppose your superior officer was under some incredible strain, to the point where he was cracking up, couldn’t think straight? If he gives some wacky order, or even worse, if he fails to act when he should, what would you do about it?”

“It’s in the book, sir. I’d go over his head.”

“Uhuh. And if said superior officer was right at the top?” Hooper opened a Red Stripe; he tossed the ring into the water, and it glinted as it spiralled down to oblivion. He held out a sandwich to Wallis but the colonel shook his head.

“Excuse me, but the man at the top is the President.”

Hooper didn’t reply. He sipped froth off the top of the can. Wallis said, quietly, “I advise you to proceed with extreme caution, General. You’re on a minefield.”

“Who isn’t these days? I repeat my question.”

“I get the drift, General, but we serve a democracy, not some banana republic. If the man at the top gets it wrong the people throw him out, not the Army.”

“Sure.” The general re-cast the line. It whipped through the air, and fresh ripples spread over the smooth lake surface. “A hypothetical, like I said. Suppose Eagle One has cracked under the strain. Gone pacifist, can’t fulfil his duties, whatever. So he has to be removed. But say the act of removing him leads to a nuclear strike against America?”

“How could that situation arise?”

“Simple. What do you impeach the President with? Failing to counterstrike against the Russians? Do we go public with Nemesis? And what would our Kremlin friends do then? Wait for us to zap them? Fact is, they would—”

“Now hold it there, sir. The only thing you go public with is that the President is unfit for office because he’s ill.”

“Get real, Wallis, there are intelligent men in the Kremlin. They would read the signs. They would have to pre-empt our strike. You want to gamble America on the Russians being dumb? That’s some chip to put on the table.”

“The fact remains that the National Command Authority rests with the President, not with traitors.”

“Colonel, your head is stuffed with mush. Remember your school history? Remember how the good guys always won, eventually? How can this be? It’s not God, it happens by definition. The winners shape what later generations believe to be good. By definition, retrospective definition, the patriots are the guys who win and the traitors are the guys who lose. Maybe it’s okay for Eagle One to let our country be attacked and do nothing. Maybe he can waive his Oath of Office. Maybe our Peacemakers and our B52s and our entire defence posture, they were always a big bluff, we never intended to retaliate when the nukes were pouring down on our frigging cities. Is that your line, Colonel? Who’s the patriot — the guy who supports his country or the one who brings it down by supporting faulty constitutional structures?”

“General, I would like for us to go back now.”

“They’ll bite, Foggy, give them time. Deal with the facts. Fact One, Nemesis is coming in: we’re under attack now. Fact Two, the Chief is psychologically paralysed: he’s unable to discharge his duty to defend America. Fact Three, any appeal to the people by way of Senate or Supreme Court or any constitutional mechanism alerts the Russians and exposes us to nuclear annihilation. That’s why you’re here, that’s the problem, and I still haven’t heard your solution.”

“Are you asking me to join a conspiracy?”

Hooper paused, then he grinned slyly and said: “Hell no, Foggy, this is a purely hypothetical discussion, remember? You’re being asked to think. For the first time in your life, to judge by your performance so far.”

“Sure. Hypothetical like the man from Mars.”

Hooper forced the point relentlessly. “What we have here is a flaw built into the Constitution. Say your Commander in Chief is abandoning his responsibilities, betraying his Oath of Office. Now say that public impeachment of said Chief would alert the enemy and bring forth the Day of Judgement. What I need from you is an answer: what would you do about it?”

“Not my problem.”

“On the contrary, Foggy, for reasons which will emerge this evening, you’re the key. Answer my question.”

Wallis felt as if doors were closing all around him. He said, “I’ll have that beer now.”

Hooper tried another tack. He wedged the fishing rod between his knees and reached for a can, tossing it to the soldier; water lapped against the underside of the boat with the slight movement. He opened his briefcase and pulled out a sheet of paper. “Typed it out this morning. Listen:

“Okay so far? Now listen to this:

“Straight from the horse’s mouth, boy, from Thomas Jefferson. The guy who wrote the frigging Constitution. You know, reading this, Jefferson practically anticipated Nemesis.”

“I know what you’re asking me. I need time.”

“Time, laddie, is the one commodity we do not have. Hey!” The line went taut. Hooper began to pull at the rod, reeling it in. “Hell, Foggy,” the CJCS went on in a more conciliatory tone, “we’ve all been programmed with particular values and these work for us nearly all the time, but democracy is only a tool. It has limits like any other tool and sometimes you have to do things for the public good that the public would lynch you for if… damn you, I’m trying to talk to this guy… look, this is a new game and you need new rules… stop wriggling…” Hooper stood up and the boat rocked dangerously as he reached out for a writhing fish.

“Steelhead, General, it’s a beauty.”

“Time’s running out, Colonel, and we need to know where you stand.”

“We?”

“Party starts about eight o’clock. We’ll be looking for answers.” Hooper, grimacing horribly, held up the squirming fish. “Now what the hell’s bells do I do with this?”

The Party

There’s a conspiracy to overthrow the President, maybe kill him. They want me to join it, and I’m thinking about it.

The gorilla leaned precariously backwards, mouth agape, scratching its armpits and making what it imagined were gorilla-like noises. A French whore, her slim legs straddling the neck of her onion-selling companion, stretched her arm over the gorilla, unsteadily trying to pour a glass of red Martini down its throat. The onion seller staggered, the whore screamed, Martini arced through the air and a little crowd cheered as they collapsed on to the grass and the gorilla jumped up and down shouting Ooh! Ooh! Ooh!

God, I hate these people.

Wallis had another problem. She was a dusky, blonde, man-eating southern belle, full of pouting coyness; she was dressed in a red crinoline dress of alarming cleavage; and she was also, Wallis had learned with increasing desperation, persistent to the point of obtuseness. Ten minutes of guttural snarling in response to her subtle probing had failed to dislodge her.

“What exactly do you do, honey?” she finally asked outright, in an Alabama drawl.

“I’m a sanitary engineer,” he said in a sudden inspiration.

“You mean you’re not in movies?” she asked in dismay, the demure pout vanishing and the accent becoming pure Bronx.

“Hell no, I’m in excrement, Miss. You know the Chinese have been spreading sewage on their fields for thousands of years? Well a bunch of us thought, why can’t we do the same here? So we’ve got a pilot plant going, trying to turn the sludge into little pellets for fertilizer. It’s working fine except the stuff smells, but we’re working on that too. Say, that guy near the marquee — oh, he’s just gone in — wasn’t that Hal Brooker?”

“Hal Brooker the movie producer?” she asked, turning.

“Yeah I think so. They tell me he’s casting for some costume piece about the Civil War. Anyway, the beauty is, we extract the methane from the crap and use it as a fuel to operate the process. So the plant costs nothing to run, isn’t that exciting?”

“Real exciting,” she said. “Listen, it’s been nice talking to you.”

“But there’s more. Methane is a greenhouse gas,” Wallis called after the retreating figure. “By burning it up we’re helping the environment.” But Miss Low Cleavage had vanished along the flight path to the marquee.

God, I hate these people, Wallis thought again. He drifted casually across the lawn, drink in hand, judging the ebb and flow of the crowd. Past the pool. Don’t catch anybody’s eye. Expensive bridgework sparkled at him out of a tanned face; Wallis pretended not to see it. People were dancing. The Tijuana Brass were sending soft, metallic notes over the rich, the beautiful and the Mexican waiters in short red jackets and tight black trousers.

Report the conspiracy and condemn my son to death. A boy of sixteen, somewhere in the Alleghenies.

Down the steps to the patio, where a large pig was covered in banana leaves, with its body cavity stuffed and its alimentary canal replaced by a long metal spit. The pig rotated unhappily about its horizontal axis while flames roasted its flesh and its fellow mammals nibbled at canapés and drank tequila from salt-encrusted glasses. The smell of burning charcoal and flesh hovered over the party. Wallis passed by.

Report it to whom? How deep does the treason go?

About fifty yards out from the lodge, the crowds began to thin. Little clusters of people chattered and laughed under the floodlit magnolia trees and the monkey puzzles. The trees were draped with tinsel and linked by long chains of multi-coloured lanterns; but the Christmas lights were more for effect than illumination, and here the shadows were dark. An overheated Santa Claus, his face flushed, was into a serious discussion with a Barbary pirate. Wallis nodded to them but he passed by unnoticed. Then he was at the edge of the lawn, marked out by bougainvillaea. He glanced behind, and casually strolled through them, into the shadows and the fir trees.

He went steadily on, the carpet of pine crackling under his feet. A couple of hundred yards in he stopped. There were shafts of light through the branches, but no human silhouettes: he was alone. Latin American rhythm was still in the air, but the night sounds of the forest were beginning to compete.

But what if the President is the traitor, and the conspirators are the loyal Americans? Are the patriots really the guys who win, by definition?

He came across a track, just visible in the darkness. Whether made by humans or large animals he could not say, but he followed it. It climbed steeply up. About half a mile from the lodge, panting with exertion, he cut away from the path and wandered randomly, still climbing. He came to a clearing about twenty yards wide, and sat down. The ground was bone dry and covered with moss. Pinewood scented the air. There was a gust of laughter and a woman’s scream from far below. Someone had fallen or jumped into the pool.

I don’t need to think about stuff like that. The President is my commanding officer. I obey his orders. Period.

A half moon had risen over the mountains to the right, and it was reflecting off the snowy peaks, and the roofs of the Mercs and Porsches parked behind the lodge. The Pacific was a huge black hole over to the left.

The classic Nuremberg Defence. I vass only obeying orders.

Wallis had a brief, fantastic urge to get out of it, find a freeway, hitch a lift to anywhere. But not at night, in flowing Arab robes. Not even in California.

There was a metallic glint from far along the approach road to the lodge. Wallis could just make out a shadowy figure, standing. The man might have been speaking into a walkie-talkie.

I’m not cut out for this frigging moral dilemma stuff.

The soldier lay back, his eyes by now dark-adapted. The

broad swathe of the Milky Way was overhead, dazzling, amazing. The filmy ribbon was divided by a great black rift; it swirled across the sky, a highway for gods and ghosts and creatures of the mind.

Was Jefferson right? Country before obedience? But who sets the acceptable limits on obedience? The guys giving the orders?

Something came into his vision, approaching from the Pacific. It was a moving star. It grew brighter and Wallis sat up. A faint chopping sound came over “Stranger on the Shore” and the shrilling cicadas. A helicopter. Two miles out from the lodge, its lights were extinguished. It was just visible in the moonlight. It flew low over the trees, descending. The soldier lost it behind a hill but it reappeared, sinking towards the lodge. It touched down about three hundred yards back from the car park. A solitary figure came out, bent double, and moved briskly towards the back of the lodge. The chopper revved up, rose and soared away, following the line of the approach road and disappearing from Wallis’s sight.

Wallis wondered about that. He was startled to find himself wondering about the beliefs, quietly held and strongly cherished, which had guided his life.

Maybe everything I’ve ever believed is junk. Maybe patriotism and loyalty and morality are just brain implants, devices put in my head from the age of five for purposes of control. Maybe it’s all just a game and there’s no right and wrong beyond my own sense of right and wrong. So follow my private conscience and screw the rules?

He lit up a small Jamaica cheroot, his match throwing a brief circle of light around him. He was still thinking in confused circles, a cigar later, when the hairs on the back of his head began to prickle. There was the faintest crackle of breaking pine needles, somewhere behind him. Casually, he stood up and turned. A young man, standing in the shadows. Twenty yards away. Smart, dark suit, close-cropped hair. Motionless as a statue.

“Sorry to startle you, sir. General Hooper’s compliments. He requests that you rejoin the party.”

“Evening, fella. Now how the hell did you find me way up here?” With a gut-wrenching start, Wallis realized that he must have been under surveillance from the moment he had left the party.

“If you’ll follow me down, sir.”

The party was three drinks noisier. The Tijuana Brass were into some frenetic number, but a young couple were dancing, waist-high in the water, to some private music of their own. Wallis followed the young man across the lawn, past the pool and over the patio. The young man nodded farewell and made off in unparty-like, military strides. A fat man in dark glasses and a blue sombrero had a slice of pork wedged between two thick slices of bread in one hand, and a large cigar in the other. He saw Wallis and detached himself from a group. Silver sequins covered the man’s sombrero and extended down over his black suit, as if he had been showered with sticky confetti. Wallis recognized him first by the whiff of Macanudo cigar smoke.

“Ah, there you are, Foggy. Great party, huh? Saw you and the Farmington girl. Should’ve stuck in there, boy, that family owns half of Texas.”

“Which half?”

“The one Margaret doesn’t own.”

“I’m an old married man, sir,” said Wallis.

“Sure you are, yes sirree. Son, you can’t just hide away like that, the world’s too small and we’re too smart. You want to mix mix mix. We got a visitor. Follow follow follow.”

Hooper, wriggling his fat bottom energetically, rumba’d his way past the now half-eaten pig. He gobbled the last of his sandwich and lifted two red Martinis from a passing silver tray, leaving the smoking cigar. He blew the waiter a kiss, but the man’s Aztec features remained frozen. Then the soldiers were through the open French windows of the lodge. A log fire crackled in the downstairs room, throwing its flickering light over a dozen hugging couples.

Wallis followed his leader up the pinewood stairs and along a corridor whose floor was soft with Chinese carpet and whose subdued lighting showed walls lined with paintings signed by de Heem, Marieschi and Laurencin. They passed Wallis’s bedroom and turned left into a small study, all red decor and mock colonial furniture. The band had started up on “Rudolf the Red-Nosed Reindeer” and the door shut it off with a pneumatic clunk.

A werewolf, in a dark three-piece suit, was lounging back in a grey swivel chair behind a desk, the hairs of its face bristling. A lamp and a thin, red book were on the desk, which was otherwise bare. Eyes assessed Wallis from behind the mask. The werewolf indicated chairs and the soldiers sat down. Hooper took off his sombrero and dropped it to the floor, and the bonhomie went off with it. The soldiers put their drinks on the desk.

“The Ayrab — is he with us or not?” the werewolf asked.

“We have a definite maybe,” Hooper replied.

“What’s his hangup?”

“Some crap about his oath of allegiance.”

“Look,” said Wallis, “what General Hooper tells me is that I have two duties, one to my President and one to my country. The two have always coincided. Until now. What we have now is a President unable to act because he’s frozen by cowardice or pacifism or whatever, and I have to ask, which comes first, President or country?”

The werewolf nodded encouragement, but its eyes were filled with caution.

“My oath of allegiance is to the Constitution, not the President. But, we have procedures. Remove him constitutionally, I tell the General here. But he tells me that the act of so removing the President is too dangerous. The Russians will cotton on to what’s happening and try to nuke us, out of fear for themselves. The story he’s trying to sell me is that the price of constitutional action is the obliteration of America. Which would make the Constitution a bit pointless in the first place.”

“He’s grasped the issue. I told you he’s a bright boy,” said Hooper.

“But what the General forgot to mention,” Wallis continued, “is that the Chief might act at the last. Maybe he’s praying for a miracle. When the Almighty fails to oblige, the President might still come up with the Major Attack Option. We just won’t know until Nemesis is practically in our air space. Any removal of the Chief before the last seconds is blatant mutiny.”

Hooper made a noise like escaping steam, and gulped down the second of his drinks. Bellarmine took off his mask and said: “Colonel, it’s the only way we ever thought to operate.”

“I don’t know why I’m listening to this. This chatter is about treason. The decision to nuke belongs to the President of the United States and him alone.”

“I don’t believe so,” the Secretary of Defense replied calmly. He opened the book in front of him. “Truman document NSC memorandum number thirty invests the authority to launch nukes with the President. Okay. But there’s an answer,” he continued. “Listen to this. Here is Section Four of the Twenty-fifth Amendment to the Constitution:

“Now hold on, sir,” said Wallis. “Who are the executive department? Surely at least the Cabinet? What about presidential aides?”

“Why not the whole frigging civil service?” Hooper interrupted. “Let’s wait for the cruise missiles to swarm out of Chesapeake Bay like Venus arising and then get the Speaker out of his bed, assemble Congress for a nice cosy debate and have the typists standing by for the written declaration. The missiles will get here faster than you can read it, never mind type it, but hell, I’m just a soldier, I guess we have to get the Supreme Court in on the act while the bombs are falling.”

“Ease off, Sam, you’re on too much choke,” said the Secretary of Defense. “Wallis, I respect your need for a legal basis, but it exists. The authority for launching nuclear weapons passes through the President, the Vice-President and myself as SecDef. The procedural requirement is that a decision to launch is made in consultation with Hooper here as Chief of JCS.”

“That means two against two,” said Wallis, “with the President carrying the ultimate authority.”

“There’s a loophole,” said Bellarmine. “In the context of the Situation Room, with a nuclear strike in the balance, and each and every second of huge importance, Hooper and I alone are the principal officers of the executive department. On the issue of presidential fitness to discharge his powers and duties, Hooper and I alone make the decision. We don’t consult the cabinet, and we dispense with written declarations. The guys who wrote this stuff just didn’t have this situation to handle.”

“Seems to me that, by the Twenty-fifth, if you remove Grant you end up with the Vice-President,” said Wallis. “Where does McCulloch stand?”

Bellarmine said, “He hasn’t been briefed. He knows nothing about Nemesis.”

“Come on, pal, McCulloch’s a chimpanzee,” Hooper interrupted. “Fat wino shopkeeper with an IQ about sixty. He couldn’t even grasp the issues. Everybody knows Grant just chose him for the Southern vote. You want a chimpanzee to make the decision for a nuclear strike? Is that what you want, Wallis? The decision left to a chimpanzee?”

“Yes, sir, if it’s next in the chain of command.”

Bellarmine tapped his fingers on the table. “McCulloch won’t be available for consultation.”

“What does that mean in plain English, sir?”

Hooper said, “Foggy, you might want to consider whether that’s an appropriate tone to address the Secretary. What you’ve just been told is all you need to know. McCulloch won’t be available for consultation.”

“But by the Twenty-fifth, you need the Vice-President to remove the President.”

“He won’t be available for consultation,” Hooper repeated in a voice which closed the matter.

Bellarmine continued. “Our problem is this, Colonel Wallis. Suppose we remove Grant by wielding the Twenty-fifth. Would the Communications personnel then accept my authority as President pro tempore? The big enemy is the clock. The whole transfer of command has to be over in seconds. There will be no time for long explanations. Or even short ones.”

“The swiftest rebellion in history,” said Hooper. “It has to be over and the new chain of command in place in the seconds between the asteroid entering our air space and the blast reaching our silos.”

“Which is where you come in, Wallis, you and your Signals background,” Bellarmine continued. “A transfer will come through for you in the next day or two. You will be given command of the communications room. Briefing sessions are being set up for you. You will be in charge of the personnel at the crucial moment. The decision that Communications accepts my authority will be made by you. Our counterstrike will then be enabled.”

“You’re trying to slip one over on me,” Wallis insisted. “If the President is removed you still have the Vice-President.”

Hooper banged a fist on the table. “We have here the most doggone stubborn soldier in this man’s army.” Bellarmine raised a hand to silence the Chief of the JCS.

Wallis bowed his head for some seconds. Then he said, thinking as he spoke, “I suppose if the Vice-President is out of it, and the President is legitimately removed by the Twenty-fifth, and SecDef at least is the only relevant principal officer in the circumstances, then yes”—he seemed to come to a decision—“the SecDef does become the Acting President. Gentlemen, I can’t connive in the removal of the Vice-President from the decision-making process. But if for whatever reason he is absent at the crucial moment, I can then follow your orders with a clear conscience.”

In a moment of panic, Wallis realized that with these words he had become a party to a plot to overthrow the President of the United States and launch a nuclear strike in which the dead would be counted in the hundreds of millions. “Oh Holy Christ,” he added, suddenly feeling nauseous.

Bellarmine half-smiled.

“Margaret’s fixed up for a fireworks display about now,” Hooper said, picking up his sombrero.

“I’ll want to bring some of my own people with me, people who know me,” Wallis said, cold sweat developing on his brow.

Hooper stood up. “Sure and begorrah. Just let me have their names. We shouldn’t miss it.”

Bellarmine turned into a werewolf again.

The crowd Ooh’d and Aah’d as rockets whooshed into the night sky, exploding with a Whump! into multi-coloured stars, while a dazzling waterfall of silver flame poured expensively on to the far end of the lawn. Wallis thought of the shadowy figure he had seen on the approach road, and the polite young man who had known just where to find him in the dark woods.

If I’d made for the freeway, I would probably now be wrapped in chains, and spiralling down towards the bottom of Lake Pepsi: an act of patriots, for love of country.

Soft flesh was pressing against his arm. Another starlet-in-waiting, hormones awash, dark eyes staring up into his; she said isn’t it exciting; and he slid an arm around her waist and said Yeah sister, cool, like I’m glad I slipped out of the AIDS hospice for the night.