Imperial Earth

11. Sirius

After three hundred years of spaceships that were mostly fuel tanks, Sirius was not quite believable. She seemed to have far too many windows, and there were entrance hatches in most improbable places, some of them still gaping open as cargo was loaded. At least she was taking on some hydrogen, thought Duncan sourly; it would be adding insult to economic injury if she made the round trip on a single fueling. She was capable of doing this, it was rumored, though at the cost of doubling her transit time.

It was also hard to believe that this stubby cylinder, with the smooth mirror-bright ring of the radiation baffle surrounding the drive unit like a huge sunshade, was one of the fastest objects ever built by man. Only the interstellar probes, now far out into the abyss of their centuries-long journeys, could exceed her theoretical maximum—almost one percent of the velocity of light. She would never achieve even half this speed, because she had to carry enough propellant to slow down and rendezvous with her destination. Nevertheless, she could make the voyage from Saturn to Earth in twenty days, despite a minor detour to avoid the hazards—largely psychological—of the asteroid belt.

The forty-minute flight from surface to parking orbit was not Duncan’s first experience of space; he had made several brief trips to neighboring moons, aboard this same shuttle. The Titanian passenger fleet consisted of exactly five vessels, and as none possessed the expensive luxury of centrifugal gravity, all safety belts were secured throughout the voyage. Any passenger who wished to sample the joys and hazards of weightlessness would have just under two hours to experience it aboard Sirius, before the drive started to operate. Although Duncan had always felt completely at ease in free fall, he let the stewards float him, an inert and unresisting package, through the airlock and into the ship.

It had been rather too much to expect the Centennial Committee to provide a single cabin—there were only four on the ship—and Duncan knew that he would have to share a double. L.3 was a minute cell with two folding bunks, a couple of lockers, two seats—also folding—and a mirror-vision screen. There was no window looking out into space; this, the Welcome Aboard! brochure carefully explained, would create unacceptable structural hazards. Duncan did not believe this for a moment, and wondered if the designers feared an attempt by claustrophobic passengers to claw a way out.

And there were no toilet facilities—these were all in an adjacent cubicle, which serviced the four cabins around it. Well, it was only going to be for a few weeks...

Duncan’s spirits rose somewhat after he had gained enough confidence to start exploring his little world. He quickly learned to visualize his location by following the advice printed on the shipboard maps; it was convenient to think of Sirius as a cylindrical tower with ten floors. The fifty cabins were divided between the sixth and seventh floors. Immediately below, on the fifth level, was the lounge, recreation and dining area.

The territory above these floors was forbidden to passengers. Going upward, the remaining levels were Life Support, Crew Quarters, and—forming a kind of penthouse with all-round visibility—the Bridge. In the other direction, the four levels were Galley, Hold, Fuel, and Propulsion. It was a logical arrangement, but it would take Duncan some time to discover that the Purser’s Office was on the kitchen level, the surgery next to the freight compartment, the gym in Life Support, and the library tucked away in an emergency airlock overlapping levels Six and Seven...

During the circumnavigation of his new home, Duncan encountered a dozen other passengers on a similar voyage of exploration, and exchanged the guarded greetings appropriate among strangers who will soon get to know each other perhaps all too well. He had already been through the passenger list to see if there was anyone on board he knew and had found a few familiar Titanian names, but no close acquaintances. Sharing cabin L.3, he had discovered, was a Dr. Louise Chung; but the parting with Marissa still hurt too much for the ‘Louise’ to arouse more than the faintest flicker of interest.

In any event, as he found when he returned to L.3, Dr. Chung was a bright little old lady, undoubtedly on the far side of a hundred, who greeted him with an absent-minded courtesy which, even by the end of the voyage, never seemed to extend to a complete recognition of his existence. She was, he soon discovered, one of the Solar System’s leading mathematical physicists, and the authority on resonance phenomena among the satellites of the outer planets. For half a century she had been trying to explain why the gaps in Saturn’s rings were not exactly where all the bet theories demanded.

The two hours ticked slowly away, finally seeming to move with a rush toward the expected announcement: “This is Captain Ivanov speaking at minus five minutes. All crew members should be on station or standby, all passengers should have safety straps secured. Initial acceleration will be one hundredth gravity—ten centimeters second squared. I repeat, one hundredth gravity. This will be maintained for ten minutes while the propulsion system undergoes routine checks.”

And suppose it doesn’t pass those checks? Duncan asked himself. Do even the mathematicians know what would happen if the Asymptotic Drive started to malfunction? This line of thought was not very profitable, and he hastily abandoned it.

“Minus four minutes. Stewards check all passengers secured.”

Now that instruction could not possibly be obeyed. There were three hundred twenty-five passengers, half of them in their cabins and the other half in the two lounges, and there was no way in which the dozen harassed stewards could see that all their charges were behaving. They had made one round of the ship at minus thirty and ten minutes, and passengers who had cut loose since then had only themselves to blame. And anyone who could be hurt by a hundredth of a gee, thought Duncan, certainly deserved it. Impacts at that acceleration had about the punch of a large wet sponge.

“Minus three minutes. All systems normal. Passengers in Lounge B will see Saturn rising.”

Duncan permitted himself a slight glow of self-satisfaction. This was precisely why, after checking with one of the stewards, he was now in Lounge B. As Titan always kept the same face turned toward its primary, the spectacle of the great globe climbing above the horizon was one that could never be seen from the surface, even if the almost perpetual overcast of hydrocarbon clouds had permitted.

That blanket of clouds now lay a thousand kilometers below, hiding the whole world that it protected for the chill of space. And then suddenly—unexpectedly, even though he had been waiting for it—Saturn was rising like a golden ghost.

In all the known universe, there was nothing to compare with the wonder he was seeing now. A hundred times the size of the puny Moon that floated in the skies of Earth, the flattened yellow globe looked like an object lesson in planetary meteorology. Its knotted bands of cloud could change their appearance almost every hour, while thousands of kilometers down in the hydrogen-methane atmosphere, eruptions whose cause was still unknown would lift bubbles larger than terrestrial continents up from the hidden core. They would expand and burst as they reached the limits of the atmosphere, and in minutes Saturn’s furious ten-hour spin would have smeared them out into long colored ribbons, stretching halfway round the planet.

Somewhere down there in that inferno, Duncan reminded himself with awe, Captain Kleinman had died seventy years ago, and so had part of Grandma Ellen. In all that time, no one had attempted to return. Saturn still represented one of the largest pieces of unfinished business in the Solar System—next, perhaps, to the smoldering hell of Venus.

The rings themselves were still so inconspicuous that it was easy to overlook them. By a cosmic irony, all the inner satellites lay in almost the same plane as the delicate, wafer-thin structure that made Saturn unique. Edge on, as they were now, the rings were visible only as hairlines of light jutting out on either side of the planet, yet they threw a broad, dusky band of shadow along the equator.

In a few hours, as Sirius rose above the orbital plane of Titan, the rings would open up in their full glory. And that alone, thought Duncan, would be enough to justify this voyage.

“Minus one minute...”

He had never even heard the two-minute mark; the great world rising out of the horizon clouds must have held him hypnotized. In sixty seconds, the automatic sequencer in the heart of the drive unit would initiate its final mysteries. Forces which only a handful of living men could envisage, and none could truly understand, would awaken in their fury, tear Sirius from the grip of Saturn, and hurl her sunward toward the distant goal of Earth.

“... ten seconds... five seconds... ignition!”

How strange that a word that had been technologically obsolete for at least two hundred years should have survived in the jargon of astronautics! Duncan barely had time to formulate this thought when he felt the onset of thrust. From exactly zero his weight leaped up to less than a kilogram. It was barely enough to dent the cushion above which he had been floating, and was detectable chiefly by the slackening tension of his waist belt.

Other effects were scarcely more dramatic. There was a distinct change in the timbre of the indefinable noises which never cease on board a spacecraft while its mechanical hearts are operating; and it seemed to Duncan that, far away, he could hear a faint hissing. But he was not even sure of that.

And then, a thousand kilometers below, he saw the unmistakable evidence that Sirius was indeed breaking away from her orbit. The ship had been driving into night on its final circuit of Titan, and the wan sunlight had been swiftly fading on the sea of clouds far below. But now a second dawn had come, in a wide swathe across the face of the world he was soon to leave. For a hundred kilometers behind the accelerating ship, a column of incandescent plasma was splashing untold quintillions of candlepower out into space and across the carmine cloudscape of Titan. Sirius was falling sunward in greater glory than the sun itself.

“Ten minutes after ignition. All drive checks complete. We will now be increasing thrust to our cruise level of point two gravities—two hundred centimeters second squared.”

And now, for the first time, Sirius was showing what she could do. In a smooth surge of power, thrust and weight climbed twenty-fold and held steady. The light on the clouds below was now so strong that it hurt the eye. Duncan even glanced at the still-rising disc of Saturn to see if it too showed any sign of this fierce new sun. He could now hear, faint but unmistakable, the steady whistling roar that would be the background to all life aboard the ship until the voyage ended. It must, he thought, be pure coincidence that the awesome voice of the Asymptotic Drive sounded so much like that of the old chemical rockets that first gave men the freedom of space. The plasma hurtling away from the ship’s reactor was moving a thousand times more swiftly than the exhaust gases of any rocket, even a nuclear one; and how it created that apparently familiar noise was a puzzle that would not be solved by any naïve mechanical intuition.

“We are now on cruise mode at one-fifth gee. Passengers may unstrap themselves and move about freely—but please use caution until you are completely adapted.”

That won’t take me very long, thought Duncan s he unbuckled himself; the ship’s acceleration gave him his normal, Titan weight. Any residents of the Moon would also feel completely at home here, while Martians and Terrans would have a delightful sense of buoyancy.

The lights in the lounge, which had been dimmed almost to extinction for better viewing of the spectacle outside, slowly brightened to normal. The few first-magnitude stars that had been visible disappeared at once, and the gibbous globe of Saturn became bleached and pale, losing all its colors. Duncan could restore the scene by drawing the black curtains around the observation alcove, but his eyes would take several minutes to readapt. He was wondering whether to made the effort when the decision was made for him.

There was a musical “Ding-dong-ding,” and a new voice, which sounded as if it came from a social stratum several degrees above the Captain’s, announced languidly: “This is the Chief Steward. Will passengers kindly note that First Seating for lunch is at twelve hundred. Please do not attempt to make any changes without consulting me: Thank you.” A less peremptory “Dong-ding-doing” signaled end of message.

Looking at the marvels of the universe made you hungry, Duncan instantly discovered. It was already 1150, and he was glad that he was in the First Seating. He wondered how many starving passengers were now converging upon the Chief Steward, in search of an earlier time slot.

Enjoying the sensation of man-made weight which, barring accidents, would remain constant until the moment of mid-voyage, Duncan went to join the rapidly lengthening line at the cafeteria. Already, his first thirty years of life on Titan seemed to belong to another existence.

12. Last Words

For one moment more, the achingly familiar image remained frozen on the screen. Behind Marissa and the children, Duncan could see the two armchairs of the living room, the photograph of Grandfather (as usual, slightly askew), the cover of the food-distribution hatch, the door to the main bedroom, the bookcase with the few but priceless treasures that had survived two centuries of interplanetary wandering... This was his universe. It held everything he loved, and now he was leaving it. Already, it lay in his past.

It lay only three seconds away, yet that was enough. He had traveled a mere million kilometers in less than half a day; but the sense of separation was already almost complete. It was intolerable to wait six seconds for every reaction and every answer. By the time a reply came, he had forgotten the original question and had started to say something else. And so the attempted conversation had quickly degenerated into a series of stops and starts, while he and Marissa had stared at each other in dumb misery, each waiting for the other to speak... He was glad that the ordeal was over.

The experience brought home to him, as nothing else had yet done, the sheer immensity of space. The Solar System, he began to suspect, was not designed for the convenience of Man, and that presumptuous creature’s attempts to use it for his own advantage would often be foiled by laws beyond his control. All his life, Duncan had assumed without question that he could speak to friends or family instantly, wherever he might be. Yet now—before he had even passed Saturn’s outer moons!—that power had been taken from him. For the next twenty days, he would share a lonely, isolated bubble of humanity, able to interact with his fellow passengers, but cut off from all real contact with the rest of mankind.

His self-pity lasted only a few moments. There was also an exhilaration—even a freedom—in this sense of isolation, and in the knowledge that he was setting forth on one of the longest and swiftest voyages that any man could make. Travel to the outer planets was routine and uneventful—but it was also rare, and only a very small fraction of the human race would ever experience it. Duncan remembered a favorite Terran phrase of Malcolm’s, usually employed in a different context, but sound advice for every occasion: “When it’s inevitable, relax and enjoy it.” He would do his best to enjoy this voyage.

Yet Duncan was exhausted when he finally climbed into his bunk at the end of his first day in space. The strain of innumerable farewells, not only to his family but to countless friends, had left him emotionally drained. On top of this, there were all the nagging worries of departure: What had he forgotten to do? What vital necessities had he failed to pack? Had all his baggage been safely loaded and stowed? What essential good-byes had he overlooked? It was useless worrying about these matters now that he was speeding away from home at a velocity increasing by twenty-five thousand kilometers an hour, every hour, yet he could not help doing so. Tired though he was, his hyperactive brain would not let him sleep.

It takes a real genius to make a bed that can be uncomfortable at a fifth of a gravity, and luckily the designers of Sirius had not accepted this challenging assignment. After thirty minutes or so, Duncan began to relax and to get his racing thoughts in order. He prided himself on being able to sleep without artificial aids, and it looked as if he would be able to dispense with electronarcosis after all. That was, of course, supposed to be completely harmless, but he never felt properly awake the next day.

You’re falling asleep, he told himself. You won’t know anything more until it’s time for breakfast. All your dreams are going to be happy ones...

A sound like a small volcano clearing its throat undid the good work of the last ten minutes. He was instantly wide awake, wondering what disaster had befallen Sirius. Not until several anxious seconds had passed did he realize that some antisocial shipmate had found it necessary to visit the adjacent toilet.

Cursing, he tried to recapture the broken mood and to return to the threshold of sleep. But it was useless; the myriad voices of the ship had started to clamor for his attention. He seemed to have lost control of the analytical portion of his brain, and it was busy classifying all the noises from the surrounding universe.

It had been hours since he had really noticed the far-off, ghostly whistling of the drive. Every second Sirius was ejecting a hundred grams of hydrogen at a third of the velocity of light—a trifling loss of mass, yet it represented meaningless millions of gigawatts. During the first few centuries of the Industrial Revolution, all the factories of Earth could not have matched the power that was now driving him sunward.

That incongruously faint and feeble scream was not really disturbing, but it was overlaid with all sorts of other peculiar sounds. What could possibly cause the “Buzz... click, click... buzz,” the soft “thump... thump... thump,” the “gurgle, hisssss,” and the intermittent “whee-wheee-whee” which was the most maddening of all?

Duncan rolled over and tried to bury his head in the pillows. It made no difference, except that the higher-pitched sounds got filtered out and the lower frequencies were enhanced. He also became more aware of the steady pulsation of the bed itself, at just about the ten cycles per second nicely calculated to produce epileptic fits.

Hello, that was something new. It was a kind of dispirited “ker-plunk, her-plunk, ker-plunk” that might have been produced by an ancient internal combustion engine in the last stages of decrepitude. Somehow, Duncan seriously doubted that i.c. engines, old or new, were to be found aboard Sirius.

He rolled over on the other side—and then became conscious of the slightly cold airstream from the ventilator hitting him on his left cheek. Perhaps if he ignored it, the sensation would sink below the threshold of consciousness. However, the very effort of pretending it wasn’t there focused attention upon the annoyance.

On the other side of the thin partition, the ship’s plumbing once again advertised its presence with a series of soft thumps. There was an air bubble somewhere in the system, and Duncan knew, with a deadly certainty, that all the engineering skills aboard the Sirius would be unable to exorcise it before the end of the voyage.

And what was that? It was a rasping, whistling sound, so irregular that no well-adjusted mechanism could possibly have produced it. As Duncan lay in the darkness, racking his brains to think of an explanation, his annoyance slowly grew to alarm. Should he call the steward and report something had gone wrong?

He was still trying to make up his mind when a sudden explosive change in pitch and intensity left him in no doubt as to the sound’s origin. Groaning and cursing his luck, Duncan resigned himself to a sleepless night.

Dr. Chung snored...

Some was gently shaking him. He mumbled “Go away,” then swam groggily upward from the depths of slumber.

“If you don’t hurry,” said Dr. Chung, “you’re going to miss breakfast.”

13. The Longest Voyage

“This is the Captain speaking. We will be performing a final out-of-ecliptic velocity trim during the next fifteen minutes. This will be your last opportunity for a good view of Saturn, and we are orienting the ship so that it will be visible through the B Lounge windows. Thank you.”

Thank you, thought Duncan, though he was a little less grateful when he reached B Lounge. This time too many other passengers had been tipped off by the stewards. Nevertheless, he managed to obtain a good vantage point, even though he had to stand.

Though the journey had scarcely begun, Saturn already seemed far away. The planet had dwindled to a quarter of its accustomed size; it was now only twice as large as the Moon would appear from Earth.

Yet though it had shrunk in size, it had gained in impressiveness. Sirius had risen several degrees out of the planet’s equatorial plane, and now at last he could see the rings in all their glory. Thin, concentric silver haloes, they looked so artificial that it was almost impossible to believe that they were not the work of some cosmic craftsman whose raw materials were worlds. Although at first sight they appeared to be solid, when he looked more carefully Duncan could see the planet glimmering through them, its yellow light contrasting strangely with their immaculate, snowy whiteness. A hundred thousand kilometers below, the shadow of the rings lay in a dusky band along the equator; it could easily have been taken for an unusually dark cloud belt, rather than something whose cause lay far out in space.

The two main divisions of the rings were apparent at the most casual glance, but a more careful inspection revealed at least a dozen fainter boundaries where there were abrupt changes in brightness between adjacent sections. Ever since the rings had been discovered, back in the seventeenth century, mathematicians like Dr. Chung had been trying to account for their structure. It had long been known that the attractions of Saturn’s many moons segregated the billions of orbiting particles into separate bands, but the details of the process were still unclear.

There was also a certain amount of variation within the individual bands themselves. The outermost ring, for example, showed a distinct mottling or beadiness, and a tiny clot of light was clearly visible near its eastern extremity. Was this, Duncan wondered, a moon about to be born—or the last remnants of one that had been destroyed?

Rather diffidently, he put the question to Dr. Chung.

“Both possibilities have been considered,” she said. “My studies indicate the former. That condensation may, with luck, become another satellite in a few thousand years.”

“I can’t agree, Doctor,” interjected another passenger. “It’s merely a statistical fluctuation in the particle density. They’re quite common, and seldom last more than a few years.”

“The smaller ones—yes. But this is too intense, and too near the edge of the B-ring.”

“But Vanderplas’ analysis of the Janus problem...”

At that moment, it became rather like the shoot-out in an old-time Western movie. The two scientists reached simultaneously for their hip computers and then retreated, muttering equations, to the back of the lounge. Thereafter, they completely ignored the real Saturn they had come so far to study—and which, in all probability, they would never see again.

“Captain speaking. We have concluded our velocity trim and are reorienting the ship into the plane of the ecliptic. I hope you had a good view—Saturn will be a long way off next time you see it.”

There was no perceptible sense of motion, but the great ringed globe began to creep slowly down the observation window. The passengers in front craned forward to follow it, and there was a chorus of disappointed “Ohs” as it finally sank from view below the wide skirting that surrounded the lower part of the ship. That band of metal had one purpose only—to block any radiation from the jet that might stray forward. Even a momentary glimpse of that intolerable glare, bright as a supernova at the moment of detonation, could cause total blindness; a few seconds’ exposure would be lethal.

Sirius was now aimed almost directly at the sun, as she accelerated toward the inner planets. While the drive was on, there could be no rear-viewing. Duncan knew that when he next saw Saturn with his unaided eyes, it would be merely a not-very-distinguished star.

A day later, moving at three hundred kilometers a second, the ship passed another milestone. She had, of course, escaped from the planet’s gravitational field hours earlier; neither Saturn—nor, for that matter, the Sun—could ever recapture her. The frontier that Sirius was crossing now was a purely arbitrary one: the orbit of the outermost moon.

Mnemosyne, only fifteen kilometers in diameter, could claim two modest records. It had the longest period of any satellite, taking no fewer than 1,139 days to orbit Saturn, at an average distance of twenty-one million kilometers. And it also had the longest day of any body in the Solar System, its period of rotation being an amazing 1,143 days. Although it seemed obvious that these two facts must be connected, no one had been able to arrive at any plausible explanation of Mnemosyne’s sluggish behavior.

Purely by chance, Sirius passed within fewer than a million kilometers of the tiny world. At first, even under the highest power of the ship’s telescope, Mnemosyne was only a minute crescent showing no visible features at all, but as it swiftly grew to a half-moon, patches of light and shade emerged which eventually resolved themselves into craters. It was typical of all the denser, Mercury-type satellites—as opposed to the inner snow-balls like Mimas, Enceladus, and Tethys—but to Duncan it now held a special interest. It was more to him than the last landmark on the road to Earth.

Karl was there, and had been for many weeks, with the joint Titan-Terran Outer Satellite Survey. Indeed, that survey had been in progress as long as Duncan could remember—the surface area of all the moons added up to a surprising number of million square kilometers—and the TTOSS team was doing a thorough job. There had been complaints about the cost, and the critics had subsided only when promised that the survey would be so thorough that it would never be necessary to go back to the outer moons again. Somehow, Duncan doubted that the promise would be kept.

He watched the pale crescent of Mnemosyne wax to full, simultaneously dwindling astern as the ship dropped sunward, and wondered fleetingly if he should send Karl a farewell greeting. But if he did, it would only be interpreted as a taunt.

It took Duncan several days to adjust to the complicated schedule of shipboard life—a schedule dominated by the fact that the dining room (as the lounge adjacent to the cafeteria was grandly called) could seat only one third of the passengers at a time. There were consequently three sittings for each of the three main meals—so for nine hours of every day, at least a hundred people were eating, while two hundred were either thinking about the next meal or grumbling about the last. This made it very difficult for the Purser, who doubled as Entertainment Officer, to organize any shipboard activities. The fact that most of the passengers had no wish to be organized did not help him.

Nevertheless, the day was loosely structured by a series of events, at which a good attendance was guaranteed by sheer boredom. There would be a thirty-minute newscast from Earth at 0800, with a repeat at 1000, and updates in the evening at 1900 and 2100. At the beginning of the voyage, the Earth news would be at least an hour and a half late, but it would become more and more timely as Sirius approached her destination. When she reached her final parking orbit, a thousand kilometers above the Equator, the delay would be effectively zero, and watches could at last be set by the radio time signals. Those passengers who did not realize this were liable to get into a hopeless state of confusion and, even worse, to miss meal sittings.

All types of visual display, including the contents of several million volumes of fiction and nonfiction, as well as most of the musical treasures of mankind, were available in the tiny library; at a squeeze, it could hold ten people. However, there were two movie screenings every evening in the main lounge, selection being made—if the Purser could be believed—in the approved Democratic manner by public ballot. Almost all the great film classics were available, right back to the beginning of the twentieth century. For the first time in his life, Duncan saw Charlie Chaplin’s Modern Times, much of the Disney canon, Olivier’s Hamlet, Ray’s Pather Panchali, Kubrick’s Napoleon Bonaparte, Zymanowski’s Moby Dick, and many other old masterpieces that had not even been names to him. But by far the greatest popular success was If This Is Tuesday, This Must Be Mars—a selection from the countless space-travel movies made in the days before space flight was actually achieved. This invariably reduced the audience to helpless hysterics, and it was hard to believe that it had once been banned for in-flight screening because some unimaginative bureaucrat feared that its disasters—such as accidentally arriving at the wrong planet—might alarm nervous passengers. In fact, it had just the opposite effect; they laughed too much to worry.

The big event of the day, however, was the lottery on the ship’s run, simple but ingenious device for redistributing the wealth among the passengers. All that one had to do was to guess how far Sirius had traveled along her heliocentric trajectory during the previous twenty-four hours; any number of guests was permitted, at the cost of one solar each.

At noon, the Captain announced the correct result. The suspense was terrific, as he read out the figures very slowly: “Today’s run has been two—two—seven—five—nine—zero—six—four—point—three kilometers.” (Cheers and moans.) Since everyone knew the ship’s position and acceleration, it required very little mathematics to calculate the first four or five figures, but beyond that the digits were completely arbitrary, so winning was a matter of luck. Although it was rumored that navigating officers had been bribed to trim the last few decimal places by minute adjustments to the thrust, no one had ever been able to prove it.

Another wealth-distributor was a noisy entertainment called “Bingo,” apparently the main surviving relic of a once-flourishing religious order. Duncan attended one session, then decided that there were better ways of wasting time. Yet a surprising percentage of his very talented and intellectually superior companions seemed to enjoy this rather mindless ritual, jumping up and down and shrieking like small children when their numbers were called...

They could not be criticized for this; they needed some such relaxation. For they were the loneliest people in the Solar System; hundreds of millions of kilometers separated them from the rest of mankind. Everybody knew this, but no one ever mentioned it. Yet it would not have taken an astute psychologist to detect countless slightly unusual reactions—even minor symptoms of stress—in the behavior of Sirius’s passengers and crew.

There was, for example, a tendency to laugh at the feeblest of jokes, and to go into positive convulsions over catch phrases such as “This is the Captain speaking” or “Dining room closes in fifteen minutes.” Most popular of all—at least among the men—was “Any more for Cabin 44.” Why the two middle-aged and rather quiet lady geologists who occupied this cabin had acquired a reputation for ravening insatiability was a mystery that Duncan never solved.

Nor was he particularly interested; his heart still ached for Marissa and he would not seek any other consolation until he reached Earth. Moreover, with the somewhat excessive conscientiousness that was typical of the Makenzies, he was already hard at work by the second day of the voyage.

He had three major projects—one physical and two intellectual. The first, carried out under the hard, cold eye of the ship’s doctor, was to get himself fit for life at one gravity. The second was to learn all that he could about his new home, so that he would not appear too much of a country cousin when he arrived. And the third was to prepare his speech of thanks, or at least to write a fairly detailed outline, which could be revised as necessary during the course of his stay.

The toughening-up process involved a fifteen-minute session, twice a day, in the ship’s centrifuge or on the ‘race track.’ Nobody enjoyed the centrifuge; not even the best background music could alleviate the boredom of being whirled around in a tiny cabin until legs and arms appeared to be made of lead. But the race track was so much fun that it operated right around the clock, and some enthusiasts even tried to get extra time on it.

Part of its appeal was undoubtedly due to sheer novelty; who would have expected to find bicycles in space? The track was a narrow tunnel, with steeply banked floor, completely encircling the ship, and rather like an old-time particle accelerator—except that in this case the particles themselves provided the acceleration.

Every evening, just before going to bed, Duncan would enter the tunnel, climb onto one of the bicycles, and start pedaling slowly around the sixty meters of track. His first revolution would take a leisurely half minute; then he would gradually work up to full speed. As he did so, he would rise higher and higher up the banked wall, until at maximum speed he was almost at right angles to the floor. At the same time, he would feel his weight steadily increase; the bicycle’s speedometer had been calibrated to read in fractions of a gee, so he could tell exactly how well he was doing. Forty kilometers and hour—ten times around Sirius every minute—was the equivalent of one Earth gravity. After several days of practice Duncan was able to maintain this for ten minutes without too much effort. By the end of the voyage, he could tolerate it indefinitely—as he would have to, when he reached Earth.

The race track was at its most exciting when it contained two or more riders—especially when they were moving at different speeds. Though overtaking was strictly forbidden, it was an irresistible challenge, and on this voyage there were no serious casualties. One of Duncan’s most vivid and incongruous memories of Sirius would be the tinkle of bicycle bells, echoing round and round in a brightly lit circular tunnel whose blurred walls flashed by only a few centimeters away... And the race track also provided him with a more material souvenir, a pseudomedieval scroll which announced to all who were interested that I, DUNCAN MAKENZIE, OF OASIS CITY, TITAN, AM HEREBY CERTIFIED TO HAVE BICYCLED FROM SATURN TO EARTH, AT AN AVERAGE VELOCITY OF 2,176,420 KILOMETERS AN HOUR.

Duncan’s mental preparation for life on Earth occupied considerably more time, but was not quite so exhausting. He already had a good knowledge of Terran history, geography, and current affairs, but until now it had been mostly theoretical, because it had little direct application to him. Both astronomically and psychologically, Earth had been a long way off. Now it was coming closer by millions of kilometers a day.

Even more to the point, he was now surrounded by Terrans; there were only seven passengers from Titan aboard Sirius, so they were outnumbered fifty to one. Whether he liked it or not, Duncan was being rapidly brainwashed and molded by another culture. He found himself using Terran figures of speech, adopting the slightly sing-song intonation now universal on Earth, and employing more and more words of Chinese origin. All this was to be expected; what he found disturbing was the fact that his own swiftly receding world was becoming steadily more unreal. Before the voyage was finished, he suspected that he would have become half-Terran.

He spent much of his time viewing Earth scenes, listening to famous political debates, and trying to understand what was happening in culture and the arts, so that he would not appear to be a complete barbarian from the outer darkness. When he was not sitting at the viddy, he was likely to be flicking through the pages of a small, dense booklet optimistically entitled Earth in Ten Days. He was fond of trying out bits of new-found information on his fellow passengers, to study their reactions and to check on his own understanding. Sometimes the response was a blank stare, sometimes a slightly condescending smile. But everyone was very polite to him; after a while, Duncan realized that there was some truth in the old cliché that Terrans were never unintentionally rude.

Of course, it was absurd to apply a single label to half a billion people—or even to the three hundred and fifty on the ship. Yet Duncan was surprised to find how often his preconceived ideas—even his prejudices—were perfectly accurate. Most Terrans did have a quite unconscious air of superiority. At first, Duncan found it annoying; then he realized that several thousand years of history and culture justified a certain pride.

It was still too early for him to answer the question, so long debated on all the other worlds: “Is Earth becoming decadent?” The individuals he had met aboard Sirius showed no trace of that effete oversensibility with which Terrans were frequently charged—but, of course, they were not a fair sample. Anyone who had occasion to visit the outer reaches of the Solar System must possess exceptional ability or resources.

He would have to wait until he reached Earth before he could measure its decadence more precisely. The project might be an interesting one—if his budget and his timetable could stand the strain.

14. Songs of Empire

In a hundred years, thought Duncan, he could never have managed to arrange this deliberately. Masterful administration of the unforeseen, indeed! Colin would be proud of him...

It had all begun quite accidentally. When he discovered that the Chief Engineer bore the scarcely uncommon name of Mackenzie, it had been natural enough to introduce himself and to compare family trees. A glance was sufficient to show that any relationship was remote: Warren Mackenzie, Doctor of Astrotechnology (Propulsion) was a freckled redhead.

It made no difference, for he was pleased to meet Duncan and happy to chat with him. A genuine friendship had developed, long before Duncan decided to take advantage of it.

“I sometimes feel,” Warren lamented, not very seriously, “that I’m a living cliché. Did you know that there was a time when all ship’s engineers were Scots and call Mac-something-or-other?”

“I didn’t know it. Why not Germans or Russians? They started the whole thing.”

“You’re on the wrong wavelength. I’m talking about ships that float on water. The first powered ones were driven by steam—piston engines, working paddle wheels—around the beginning of the nineteenth century. Now, the Industrial Revolution started in Britain, and the first practical steam engine was made by a Scot. So when steamships began to operate all over the world, the Macs went with them. No one else could understand such complicated pieces of machinery.”

“Steam engines? Complicated? You must be joking.”

“Have you ever looked at one? More to it than you might think, though it doesn’t take long to figure it out... Anyway, while the steamships lasted—that was only about a hundred years—the Scots ran them. I’ve made a hobby of the period; it has some surprising parallels with our time.”

“Go on—surprise me.”

“Well, those old ships were incredibly slow, averaging only about ten klicks, at least for freighters. So really long journeys, even on Earth, could take weeks. Just like space travel.”

“I see. In those days, the countries on Earth were almost as far apart as the planets.”

“Well, some of them. The most perfect analogy is the old British Commonwealth, the first and last world empire. For almost a hundred years, countries like Canada, India, and Australia relied entirely on steamships to link them to Britain; the one-way journey could easily take a month or more, and was often a once-in-a-lifetime affair. Only the wealthy, or people on official business, could afford it. And—just like today—people in the colonies couldn’t even speak to the mother country. The psychological isolation was almost complete.”

“They had telephones, didn’t they?”

“Only for local use, and only a few even then. I’m talking about the beginning of the twentieth century, remember. Universal global communication didn’t arrive until the end of it.”

“I feel that the analogy is a little forced,” protested Duncan. He was intrigued but unconvinced, and quite willing to listen to Mackenzie’s arguments—as yet, with no ulterior motive.

“I can give you some more evidence that makes a better case. Have you heard of Rudyard Kipling?”

“Yes, though I’ve never read anything of his. He was a writer, wasn’t he? Anglo-American—sometime between Melville and Hemingway. English Lit’s almost unknown territory to me. Life’s too short.”

“True, alas. But I have read Kipling. He was the first poet of the machine age, and some people think he was also the finest short-story writer of his century. I couldn’t judge that, of course, but he exactly described the period I’m talking about. ‘McAndrew’s Hymn,’ for example—an old engineer musing about the pistons and boilers and crankshafts that drive his ship round the world. Its technology—not to mention its theology!—has been extinct for three hundred years; but the spirit behind it is still as valid as ever.”

“And he wrote poems and stories about the far places of the empire which make them seem quite as remote as the planets are today—and sometimes even more exotic! There’s a favorite of mine called ‘The Song of The Cities.’ I don’t understand half the allusions, but he tributes to Bombay, Singapore, Rangoon, Sydney, Aukland... make me think of Luna, Mercury, Mars, Titan...”

Mackenzie paused and looked just a little embarrassed.

“I’ve tried to do something of the same kind myself—but don’t worry, I won’t inflict my verses on you.”

Duncan made the encouraging noises he knew were expected. He was quite sure that before the end of the voyage he would be asked for his criticism—translation, praise—of Mackenzie’s literary efforts.

It was a timely reminder of his own responsibilities. While the voyage was still beginning, he had better start work.

Exactly ten minutes, George Washington had directed—not a second more. Even the President will be allowed only fifteen, and all the planets must have equal time. The whole affair is scheduled to last two and a half hours, from the moment we enter the Capitol until we leave for the reception at the White House...

It still seemed faintly absurd to travel three billion kilometers to make a ten-minute speech, even for an occasion as unique as a five hundredth anniversary. Duncan was not going to waste more than the bare minimum of it on polite formalities; anyway, as Malcolm had pointed out, the sincerity of the speech of thanks is often inversely proportional to its length.

For his amusement—and, more important, because it would help to fix the other participants in his mind—Duncan had tried to compose a formal opening, based on the list of guests that Professor Washington had provided. It started off: “Madame President, Mr. Vice President, Honorable Chief Justice, Honorable Leader of the Senate, Honorable Leader of the House, Your Excellencies the Ambassadors for Luna, Mars, Mercury, Ganymede, and Titan”—at this point he would incline his head slightly toward Ambassador Farrell, if he could see him in the crowded gallery—“distinguished representatives from Albania, Austrand, Cyprus, Bohemia, France, Khmer, Palestine, Kalinga, Zimbabwe, Eire...” He calculated that if he acknowledged all fifty or sixty regions that still existed on some form of individual recognition, a quarter of his time would be expended before he had even begun. This, obviously, was absurd, and he hoped that all the other speakers would agree. Regardless of that protocol, Duncan had decided to opt for dignified brevity.

“People of Earth” would cover a lot of ground—to be precise, five times the area of Titan, an impressive statistic which Duncan knew by heart. But that would leave out the visitors; what about “Friends from other worlds”? No, that was too pretentious, since most of them would be complete strangers. Perhaps: “Madame President, distinguished guests, known and unknown friends from many worlds...” That was better, yet somehow it still didn’t seem right.

There was more to this business, Duncan realized, than met the eye, or the ear. Plenty of people would be willing to give him advice, but he was determined, in the good old Makenzie tradition, to see what he could do himself before calling for help. He had read somewhere that the best way to learn to swim is by being thrown into deep water. Duncan could not swim—that skill being singularly useless on Titan—but he could appreciate the analogy. His career in Solar politics would start with a spectacular splash, and before the eyes of millions.

It was not that he was nervous; after all, he had addressed his whole world as an expert witness during technical debates in the Assembly. He had acquitted himself well when he weighed the complex arguments for and against mining the ammonia glaciers of Mount Nansen. Even Armand Helmer had congratulated him, despite the fact that they had reached opposing conclusions. In those debates, affecting the future of Titan, he had had real responsibility, and his career might have come to an abrupt end if he had made a fool of himself.

His Terran audience might be a thousand times larger, but it would be very much less critical. Indeed, his listeners would be friendly unless he committed the unpardonable sin of boring them.

This, however, he could not yet guarantee, for he still had no idea how he was going to use the most important ten minutes of his life.

15. At The Node

On the seas of Earth, they had called it “Crossing the Line.” Whenever a ship had passed from one hemisphere to another, there had been light-hearted ceremonies and rituals, during which those who had never traversed the Equator before were subjected to ingenious indignities by Father Neptune and his Court.

During the first centuries of space flight, the equivalent transition involved no physical changes; only the navigational computer knew when a ship had ceased to fall toward one planet and was beginning to fall toward another. But now, with the advent of constant-acceleration drives, which could maintain thrust for the entire duration of a voyage, Midpoint, or “Turnaround,” had logical impact. After living and moving for days in an apparent gravitational field, Sirius’ passengers would lose all weight for several hours, and could at least feel that they were really in space.

They could watch the slow rotation of the stars as the ship was swung through one hundred eighty degrees, and the drive was aimed precisely against its previous line of thrust, to slowly whittle away the enormous velocity built up over the preceding ten days. They could savor the thought that they were now moving faster than any human beings in history—and could also contemplate the exciting prospect that if the drive failed to restart, Sirius would ultimately reach the nearest stars, in not much more than a thousand years...

All these things they could do; however, human nature having certain invariants, a majority of Sirius’ passengers had other possibilities in mind.

It was the only chance most of them would ever have of experiencing weightlessness long enough to enjoy it. What a crime to waste the opportunity! No wonder that the most popular item in the ship’s library these last few days had been the Nasa Sutra, an old book and an old joke, explained so often that it was no longer funny.

Captain Ivanov denied, with a reasonably convincing show of indignation, that the ship’s schedule had been designed to pander to the passengers’ lower instincts. When the subject had been raised at the Captain’s table, the day before Turnaround, he had put up quite a plausible defense.

“It’s the only logical time to shut down the Drive,” he had explained. “Between zero zero and zero four, all the passengers will be in their cabins, er, sleeping. So there will be a minimum of disturbance. We couldn’t close down during the day—remember, the kitchens and the toilets will be out of action while we’re weightless. Don’t forget that! We’ll remind everyone in the late evening, but some idiot always gets overconfident, or drinks too much, and doesn’t have enough sense to read the instructions on those little plastic bags you’ll find in your cabins—no thanks, Steward, I don’t feel like soup.”

Duncan had been tempted; Marissa was beginning to fade, and there was no lack of opportunity. He had received unmistakable signals from several directions, and for groups with all values of n from one to five. It would not have been easy to make a choice, but Fate had saved him the trouble.

It was a full week, and Turnaround was only three days ahead, before he had felt confident enough of his increasing intimacy with Chief Engineer Mackenzie to drop some gentle hints. They had not been rejected out of hand, but Warren obviously wanted time to weigh the possibilities. He gave Duncan his decision only twelve hours in advance.

“I won’t pretend this might cost me my job,” he said, “but it could be embarrassing, to say the least, if it got around. But you are a Makenzie, and a Special Assistant to the Administrator, and all that. If the worst comes to the worst, which I hope it won’t, we can say your request’s official.”

“Of course. I understand completely, and I really appreciate what you’re doing. I won’t let you down.”

“Now there’s the question of timing. If everything checks out smoothly—and I’ve no reason to expect otherwise—I’ll be through in two hours and can dismiss my assistants. They’ll leave like meteors—they’ll all have something lined up, you can be sure of that—so we’ll have the place to ourselves. I’ll give you a call at zero two, or as soon after as possible.”

“I hope I’m not interrupting any—ah—personal plans you’ve made.”

“As it happens, no. The novelty’s worn off. What are you smiling at?”

“It’s just occurred to me,” Duncan answered, “that if anyone does meet the pair of us at two o’clock on the morning of Turnaround, we’ll have a perfect alibi...”

Nevertheless, he felt a mild sense of guilt as he drifted along the corridors behind Warren Mackenzie. The weightless—but far from sleeping—ship might have been deserted, for there was no occasion now for anyone to descend below the freight deck on Level Three. It was not even necessary to pretend that they were heading for an innocent assignation.

Yet the guilt was there, and he knew why. He was taking advantage of a friendship for secret purposes of his own, by suggesting that his interest in the Asymptotic Drive was no more than would be expected from anyone with a scientific or engineering background. But perhaps Warren was not as naïve as he seemed; he could hardly be unaware that the Drive posed a threat to the entire economy of Duncan’s society. He might even be trying to help, in a tactful way.

“You may be disappointed,” said Warren as they passed through the bulkhead floor separating Levels Three and Two. “There’s not much to see. But what there is is enough to give some people nightmares—which is why we discourage visitors.”

Not the most important reason, thought Duncan. The Drive was not exactly a secret; there was an immense literature on the subject, from the most esoteric mathematical papers down to popularizations so elementary that they amounted to little more than: “You pull on your bootstraps, and away you go.” But it would be fair to say that Earth’s Space Transportation Authority was curiously evasive when it came down to the practical details, and only its own personnel were allowed on the minor planet where the Drive was assembled. The few photos of Asteroid 4587 were blurred telescopic shots showing two cylindrical structures, more than a thousand kilometers long, stretching out into space on either side of the tiny world, which was an almost invisible speck between them. It was known that these were the accelerators that smashed matter together at such velocities that it fused to form the node or singularity at the heart of the Drive; and this was all that anyone did know, outside the STA.

Duncan was now floating, a few meters behind his guide, along a corridor lined with pipes and cable ducts—all the anonymous plumbing of any vehicle of sea, air, or space for the last three hundred years. Only the remarkable number of handholds, and the profusion of thick padding, revealed that this was the interior of a ship designed to be independent of gravity.

“D’you see that pipe?” said the engineer. “The little red one?”

“Yes—what about it?”

Duncan would certainly never have given it a second glance; it was only about as thick as a lead pencil.

“That’s the main hydrogen feed, believe it or not. All of a hundred grams a second. Say eight tons a day, under full thrust.”

Duncan wondered what the old-time rocket engineers would have thought of this tiny fuel line. He tried to visualize the monstrous pipes and pumps of the Saturns that had first taken men to the Moon; what was their rate of fuel consumption? He was certain that they burned more in every second than Sirius consumed in a day. That was a good measure of how far technology had progressed, in three centuries. And in another three...?

“Mind your head—those are the deflection coils. We don’t trust room-temperature superconductors. These are still good old cryogenics.”

“Deflection coils? What for?”

“Ever stopped to think what would happen if that jet accidentally touched part of the ship? These coils keep it centered, and also give it all the vector control we need.”

They were now hovering beside a massive—yet still surprisingly small—cylinder that might have been the barrel of a twentieth-century naval gun. So this was the reaction chamber of the Drive.

It was hard not to feel a sense of almost superstitious awe at the knowledge of what lay within a few centimeters of him. Duncan could easily have encircled the metal tube with his arms; how strange to think of putting your arms around a singularity, and thus, if some of the theories were correct, embracing an entire universe...

Near the middle of the five-meter-long tube a small section of the casing had been removed, like the door of some miniature bank vault, and replaced by a crystal window. Through this obviously temporary opening a microscope, mounted on a swinging arm so that it could be moved away after use, was aimed into the interior of the drive unit.

The engineer clipped himself into position by the buckles conveniently fixed to the casing, stared through the eyepiece, and made some delicate micrometer adjustments.

“Take a look,” he said, when he was finally satisfied.

Duncan floated to the eyepiece and fastened himself rather clumsily in place. He did not know what he had expected to see, and he remembered that the eye had to be educated before it could pass intelligible impressions to the brain. Anything utterly unfamiliar could be, quite literally, invisible, so he was not too disappointed at his first view.

What he saw was, indeed, perfectly ordinary—merely a grid of fine hairlines, crossing at right angles to from a reticule of the kind commonly used for optical measurements. Though he searched the brightly lit field of view, he could find nothing else; he might have been exploring a piece of blank graph paper.

“Look at the crossover at the exact center,” said his guide, “and turn the knob to the left—very slowly. Half a rev will do—either direction.”

Duncan obeyed, yet for a few seconds he could still see nothing. Then he realized that a tiny bulge was creeping along the hairline as he tracked the microscope. It was as if he was looking at the reticule through a sheet of glass with one minute bubble or imperfection in it.

“Do you see it?”

“Yes—just. Like a pinhead-sized lens. Without the grid, you’d never notice it.”

“Pinhead-sized! That’s an exaggeration, if I ever heard one. The node’s smaller than an atomic nucleus. You’re not actually seeing it, of course—only the distortion it produces.”

“And yet there are thousands of tons of matter in there.”

“Well, one or two thousand,” answered the engineer, rather evasively. “It’s made a dozen trips and is getting near saturation, so we’ll soon have to install a new one. Of course it would go on absorbing hydrogen as long as we fed it, but we can’t drag too much unnecessary mass around, or we’ll pay for it in performance. Like the old seagoing ships—they used to get covered with barnacles, and slowed down if they weren’t scraped clean every so often.”

“What do they do with old nodes when they’re too massive to use? Is it true that they’re dropped into the sun?”

“What good would that do? A node would sail right through the sun and out the other side. Frankly, I don’t know what they do with the old ones. Perhaps they lump them all together into a big granddaddy node, smaller than a neutron but weighing a few million tons.”

There were a dozen other questions that Duncan was longing to ask. How were these tiny yet immensely massive objects handled? Now that Sirius was in free fall, the node would remain floating where it was—but what kept it from shooting out of the drive tube as soon as acceleration started? He assumed that some combination of powerful electric and magnetic fields held it in place, and transmitted its thrust to the ship.

“What would happen,” Duncan asked, “If I tried to touch it?”

“You know, absolutely everyone asks that question.”

“I’m not surprised. What’s the answer?”

“Well, you’d have to open the vacuum seal, and then all hell would break loose as the air rushed in.”

“Then I don’t do it that way. I wear a spacesuit, and I crawl up the drive tunnel and reach out a finger...”

“How clever of you to hit exactly the right spot! But if you did, when your finger got within—oh—something like a millimeter, I’d guess—the gravitational tidal forces would start to tear away at it. As soon as the first few atoms fell into the field, they’d give up all their mass-energy—and you’d think that a small hydrogen bomb had gone off in your face. The explosion would probably blow you out of the tube at a fair fraction of the speed of light.”

Duncan gave an uncomfortable little laugh.

“It would certainly take a clever man to steal one of your babies. Doesn’t it ever give you nightmares?”

“No. It’s the tool I’m trained to use, and I understand its little ways. I can’t imagine handling power lasers—they scare the hell out of me. You know, old Kipling had it all summed up, as usual. You remember me talking about him?”

“Yes.”

“He wrote a poem called ‘The Secret of the Machines,’ and it has some lines I often say to myself when I’m down here:

“But remember, please, the Law by which we live,

We are not built to comprehend a lie,

We can neither love nor pity nor forgive.

If you make a slip in handling us you die!

“And that’s true of all machines—all the natural forces we’ve ever learned to handle. There’s no real difference between the first caveman’s fire and the node in the heart of the Asymptotic Drive.”

An hour later, Duncan lay sleepless in his bunk, waiting for the Drive to go on and for Sirius to begin the ten days of deceleration that would lead to her rendezvous with Earth. He could still see that tiny flaw in the structure of space, hanging there in the field of the microscope, and knew that its image would haunt him for the rest of his life. And he realized now that Warren Mackenzie had betrayed nothing of his trust; all that he had learned had been published a thousand times. But no words or photos could ever convey the emotional impact he had experienced.

Tiny fingers began to tug at him; weight was returning to Sirius. From an infinite distance came the thin wail of the Drive; Duncan told himself that he was listening to the death cry of matter as it left the known universe, bequeathing to the ship all the energy of its mass in the final moment of dissolution. Every minute, several kilograms of hydrogen were falling into that tiny but insatiable vortex—the hole that could never be filled.

Duncan slept poorly for the rest of the night. He had dreams that he too was falling, falling into a spinning whirlpool, indefinitely deep. As he fell, he was being crushed to molecular, to atomic, and finally to subnuclear dimensions. In a moment, it would all be over, and he would disappear in a single flash of radiation...

But that moment never came, because as Space contracted, Time stretched endlessly, the passing seconds becoming longer... and longer—until he was trapped forever in a changeless Eternity.

16. Port Van Allen

When Duncan had gone to bed for the last time aboard Sirius, Earth was still five million kilometers away. Now it seemed to fill the sky—and it was exactly like the photographs. He had laughed when more seasoned travelers told him he would be surprised at this; now he was ruefully surprised at his surprise.

Because the ship had cut right across the Earth’s orbit, they were approaching from sunward, and the hemisphere below was almost fully illuminated. White continents of cloud covered most of the day side, and there were only rare glimpses of land, impossible to identify without a map. The dazzling glare of the Antarctic icecap was the most prominent surface feature; it looked very cold down there, yet Duncan reminded himself that it was tropical in comparison with much of his world.

Earth was a beautiful planet; that was beyond dispute. But it was also alien, and its cool whites and blues did nothing to warm his heart. It was indeed a paradox that Titan, with its cheerful orange clouds, looked so much more hospitable from space.

Duncan stayed in Lounge B, watching the approaching Earth and making his farewells to many temporary friends, until Port Van Allen was a dazzling star against the blackness of space, then a glittering ring, then a huge, slowly turning wheel. Weight gradually ebbed away as the drive that had taken them halfway across the Solar System decreased its thrust to zero; then there were only occasional nudges as low-powered thrustors trimmed the attitude of the ship.

The space station continued to expand. Its size was incredible, even when one realized that it had been steadily growing for almost three centuries. Now it completely eclipsed the planet whose commerce it directed and controlled; a moment later a barely perceptible vibration, instantly damped out, informed everybody that the ship had docked. A few seconds later, the Captain confirmed it.

“Welcome to Port Van Allen—Gateway to Earth. It’s been nice having you with us, and I hope you enjoy your stay. Please follow the stewards, and check that you’ve left nothing in your cabins. And I’m sorry to mention this, but three passengers still haven’t settled their accounts. The Purser will be waiting for them at the exit...”

A few derisive groans and cheers greeted this announcement, but were quickly lost in the noisy bustle of disembarkation. Although everything was supposed to have been carefully planned, chaos was rampant. The wrong passengers went to the wrong checkpoints, while the public-address system called plaintively for individuals with improbable names. It took Duncan more than an hour to get into the spaceport, and he did not see all of his baggage again until his second day on Earth.

But at last the confusion abated as people squeezed through the bottleneck of the docking hub and sorted themselves out in the appropriate levels of the station. Duncan followed instructions conscientiously, and eventually found himself, with the rest of his alphabetical group, lined up outside the Quarantine Office. All other formalities had been completed hours ago, by radio circuit; but this was something that could not be done by electronics. Occasionally, travelers had been turned back at this point, on the very doorstep of Earth, and it was not without qualms that Duncan confronted this last hurdle.

“We don’t get many visitors from Titan,” said the medical officer who checked his record. “You come in the Lunar classification—less than a quarter gee. It may be tough down there for the first week, but you’re young enough to adapt. It helps if both your parents were born...”

The doctor’s voice trailed off into silence; he had come to the entry marked MOTHER. Duncan was used to the reaction, and it had long ago ceased to bother him. Indeed, he derived a certain amusement from the surprise that discovery of his status usually produced. At least the M.O. would not ask the silly question that laymen so often asked, and to which he had long ago formulated an automatic reply: “Of course I’ve got a navel—the best that money can buy.” The other common myth—that male close must be abnormally virile “because they had one father twice”—he had wisely left unchallenged. It had been useful to him on several occasions.

Perhaps because there were six other people waiting in line, the doctor suppressed any scientific curiosity he may have felt, and sent Duncan “upstairs” to the Earth-gravity section of the spaceport. It seemed a long time before the elevator, moving out along one of the spokes of the slowly spinning wheel, finally reached the rim; and all the while, Duncan felt his weight increasing remorselessly.

When the doors opened at last, he walked stiff-legged out of the cage. Though he was still a thousand kilometers above the Earth, and his new-found weight was entirely artificial, he felt that he was already in the cruel grip of the planet below. If he could not pass the test, he would be shipped back to Titan in disgrace.

It was true that those who just failed to make the grade could take a high-speed toughening-up course, primarily intended for returning Lunar residents. This, however, was safe only for those who had spent most of their infancy on Earth, and Duncan could not possibly qualify.

He forgot all these fears when he entered the lounge and saw the crescent Earth, filling half the sky and slowly sliding along the huge observation windows—themselves a famous tour de force of space engineering. Duncan had no intention of calculating how many tons of air pressure they were resisting; as he walked up to the nearest, it was easy to imagine that there was nothing protecting him from the vacuum of space. The sensation was both exhilarating and disturbing.

He had intended to go through the check list that the doctor had given him, but that awesome view made it impossible. He stood rooted to the spot, only shifting his unaccustomed weight from one foot to the other as hitherto unknown muscles registered their complaints.

Port Van Allen circled the globe every two hours, and also rotated on its own axis three times a minute. After a while, Duncan found that he could ignore the station’s own spin; his mind was able to cancel it out, like an irrelevant background noise or a persistent but neutral odor. Once he had achieved this mental attitude, he could imagine that the was alone in space, a human satellite racing along the Equator from night into day. For the Earth was waxing visibly even as he watched, the curved line of dawn moving steadily away from him as he hurtled into the east.

As usual, there was little land visible, and what could be seen through or between the clouds seemed to have no relationship to any maps. And from this altitude there was not the slightest sign of life—still less of intelligence. It was very hard to believe that most of human history had take place beneath that blanket of brilliant white, and that, until a mere three hundred years ago, no man had ever risen above it.

He was still searching for signs of life when the disc started to contract to a crescent once more, and the public-address system called on all passengers for Earth to report to the shuttle embarkation area, Elevators Two and Three.

He just had time to stop of the “Last Chance” toilet—almost as famous as the lounge windows—and then he was down by elevator again, back into the weightless world of the station’s hub, where the Earth-to-orbit shuttle was being readied for its return journey.

There were no windows here, but each passenger had his own vision screen, on the back of the seat in front of him, and could switch to forward, rear, or downward as preferred. The choice was not completely free, though this fact was not widely advertised. Images that were likely to be too disturbing—like the final moments of docking or touchdown—were thoughtfully censored by the ship’s computer.

It was pleasant to be weightless again—if only during the fifty minutes needed for the fall down to the edge of the atmosphere—and to watch the Earth slowly changing from a planet to a world. The curve of the horizon became flatter and flatter; there were fleeting glimpses of island and the spiral nebula of a great storm, raging in silence far below. Then at last a feature that Duncan could recognize—the characteristic narrow isthmus of the California coastline, as the shuttle dropped out of the Pacific skies for its final landfall, still the width of a continent away.

He felt himself sinking deeper and deeper into the superbly padded seat, which spread the load so evenly over his body that there was the minimum of discomfort. But it was hard to breathe, until he remembered the “Advice to Passengers” he had finally managed to read. Don’t try to inhale deeply, it had said; take short, sharp pants, to reduce the strain on the chest muscles. He tried it, and it worked.

Now there was a gently buffeting and a distant roar, and the vision screen flared into momentary flame, then switched automatically from the fires of reentry to the view astern. The canyons and deserts dwindled behind, to be replace by a group of lakes—obviously artificial, with the tiny white flecks of sailboats clearly visible. He caught a glimpse of the huge V-shaped wake, kilometers long, of some vessel going at great speed over the water, although from this altitude it seemed completely motionless.

Then the scene changed with an abruptness that took him by surprise. He might have been flying over the ocean once more, so uniform was the view below. Still so high that he could not see the individual trees, he was passing over the endless forests of the American Midwest.

Here indeed was proof of Life, on a scale such as he had never imagined. On all of Titan, there were fewer than a hundred trees, cherished and protected with loving care. Spread out beneath him now were incomputable millions.

Somewhere, Duncan had encountered the phrase “primeval forest,” and now it flashed again into his mind. So must the Earth have looked in the ancient days, before Man had set to work upon it with fire and axe. Now, with the ending of the brief Agricultural Age, much of the planet was reverting to something like its original state.

Though the fact was very hard to believe, Duncan knew perfectly well that the “primeval forest” lying endlessly beneath him was not much older than Grandfather. Only two centuries ago, this had all been farmland, divided into enormous checkerboards and covered in the autumn with golden grain. “That concept of seasons was another local reality he found extremely difficult to grasp...) There were still plenty of farms in the world, run by eccentric hobbyists or biological research organizations, but the disasters of the twentieth century had taught men never again to rely on a technology that, at its very best, had an efficiency of barely one percent.

The sun was sinking, driven down into the west with unnatural speed by the shuttle’s velocity. It clung to the horizon for a few seconds, then winked out. For perhaps a minute longer the forest was still visible; then it faded into obscurity.

But not into darkness. As if by magic, faint lines of light had appeared on the land below—spiders’ webs of luminosity, stretching as far as the eye could see. Sometimes three or four lines would meet at a single glowing knot. There were also isolated islands of phosphorescence, apparently unconnected with the main network. Here was further proof of Man’s existence; that great forest was a much busier place than it appeared to be by daylight. Yet Duncan could to help comparing this modest display with pictures he had seen from the early Atomic Age, when millions of square kilometers blazed at night with such brilliance that men could no longer see the stars.

He suddenly became aware of a compact constellation of flashing lights, moving independently of the glimmering landscape far below. For a moment, he was baffled; then he realized that he was watching some great airship, cruising not much faster than a cloud with its cargo of freight or passengers. This was one experience Titan could not provide. He determined to enjoy it as soon as the opportunity arose.

And there was a city—quite a big one, at least a hundred thousand people. The shuttle was now so low that he could make out blocks of buildings, roads, parks, and a stadium blazing with light, presumably the scene of some sporting event. The city fell astern, and a few minutes later everything was lost in a gray mist, lit by occasional flashes of lightning, not very impressive by the standards of Titan. Inside the cabin, Duncan could hear nothing of the storm through which they were now flying, but the vibration of the engines had taken on a new note and he could sense that the ship was dropping rapidly. Nevertheless, he was taken completely by surprise when there was a sudden surge of weight, the slightest of jolts—and there on the screen was a sea of wet concrete, a confusion of lights, and half a dozen buses and service vehicles scurrying around in the driving rain.

After thirty years, Duncan Makenzie had returned to the world where he was born, but which he had never seen...