More Tales of Pirx the Pilot

THE HUNT ^{Translated by Louis Iribarne}

He left Port Control hopping mad. It had to happen to him, to him! The owner didn’t have the shipment—simply didn’t have it—period. Port Control knew nothing. Sure, there had been a telegram: 72 HOUR DELAY—STIPULATED PENALTY PAID TO YOUR ACCOUNT—ENSTRAND. Not a word more. At the trade councilor’s office he didn’t get anywhere, either. The port was crowded and the stipulated penalty didn’t satisfy Control. Parking fee, demurrage, yes, but wouldn’t it be best if you, Mr. Navigator, lifted off like a good fellow and went into hold? Just kill the engines, no expenditure for fuel, wait out your three days and come back. What would that hurt you? Three days circling the Moon because the owner screws up! Pirx was at a loss for a reply, but then remembered the treaty. Well, when he trotted out the norms established by the labor union for exposure in space, they started backing down. In fact, this was not the Year of the Quiet Sun. Radiation levels were not negligible. So he would have to maneuver, keep behind the Moon, play that game of hide-and-seek with the sun using thrust. And who was going to pay for this? Not the owner, certainly. Who, then—Control? Did you gentlemen have any idea of the cost of ten minutes’ full bum with a reactor of seventy million kilowatts? In the end he got permission to stay, but only for seventy-two hours plus four to load that wretched freight—not a minute more! You would have thought they were doing him a favor. As if it were his fault. And he had arrival right on the dot, and didn’t come straight from Mars, either—while the owner…

With all this he completely forgot where he was, and pushed the door handle so hard on his way out that he was thrown up to the ceiling. Embarrassed, he looked around, but no one was there. All Luna Base seemed empty. True, the big work was under way a few hundred kilometers to the north, between the Hypatia region and the Toricelli crater. The engineers and technicians, who a month ago were all over the place here, had already left for the construction site. The UN’s great project, Luna Base 2, drew more and more people from Earth.

“At least this time there won’t be any trouble getting a room,” he thought, taking the escalator to the bottom floor of the underground city. The fluorescent lamps produced a cold daylight. Every other one was off. Economizing! Pushing a glass door, he entered a small lobby. They had rooms, all right! All the rooms you wanted. He left his suitcase (it was really more a satchel) with the porter and wondered if Tyndall would make sure that the mechanics reground the central nozzle. Ever since Mars the thing had been behaving like a damned medieval cannon! He really ought to see to it himself: the proprietor’s eye and all that. But he didn’t feel like taking the elevator back up those twelve flights, and anyway, by now they had probably split up. Sitting in the airport store, most likely, listening to the latest recordings.

He walked, not really knowing where; the hotel restaurant was empty, as if closed—but behind its lunch counter sat a redhead, reading a book. Or had she fallen asleep over it? Her cigarette was turning into a long cylinder of ash on the marble top… Pirx took a seat and reset his watch to local time; and suddenly it became late, ten at night. And on board, why, only a few minutes before, it had been noon. This eternal whirl with sudden jumps in time was just as fatiguing as in the beginning, when he was first learning to fly. He ate his lunch, now turned into supper, washing it down with seltzer, which seemed warmer than the soup. The waiter, down in the mouth and drowsy like a true lunatic, added up the bill wrong, and not in his own favor, a bad sign. Pirx advised him to take a vacation on Earth, and left quietly, so as not to waken the sleeping countergirl.

He got the key from the porter and rode up to his room. He hadn’t looked at the plate yet and felt strange when he saw the number: 173. The same room he had stayed in, long ago, when for the first time he flew “that side.” But after opening the door he concluded that either this was a different room or they had remodeled it radically. No, he must have been mistaken, that other was larger. He turned on all the switches, for he was sick of darkness, looked in the dresser, pulled out the drawer of the small writing table, but didn’t bother to unpack; he just threw his pajamas on the bed and set the toothbrush and toothpaste on the sink. He washed his hands—the water, as always, infernally cold, a wonder it didn’t freeze. He turned the hot water spigot—a few drops trickled out. He went to the phone to call the desk but changed his mind: there was really no point. It was scandalous, of course—here the Moon was stocked with all the necessities, and you still couldn’t get hot water in your hotel room!

He tried the radio. The evening wrap-up—the lunar news. He hardly listened, wondering whether he shouldn’t send a telegram to the owner. Reverse the charges, of course. But no, that wouldn’t accomplish anything. These were not the romantic days of astronautics! They were long gone; now a man was nothing but a truck driver, dependent on those who loaded cargo on his ship. Cargo, insurance, demurrage… The radio was muttering something. Hold on—what was that?… He leaned across the bed and moved the knob of the apparatus.

“—in all probability the last of the Leonid swarm.” The soft baritone of the speaker filled the room. “Only one apartment building suffered a direct hit and lost its seal. By a lucky coincidence its residents were all at work. The remaining meteorites caused little damage, with the exception of one that penetrated the shield protecting the storerooms. According to our correspondent’s report, six universal automata designated for tasks on the construction site were totally destroyed. There was also damage to the high-tension line, and telephone communication was knocked out, though restored within a space of three hours. We now repeat the major news. Earlier today, at the opening of the Pan-African Congress…”

He shut off the radio and sat down. Meteorites? A swarm? Well, yes, the Leonids were due, but still the forecasts—those meteorologists were always fouling up, exactly like the synoptics on Earth. Construction site—it must have been that one up north. But all the same, atmosphere was atmosphere, and its absence here was damned inconvenient. Six automata, if you please. At least no one was hurt. A nasty business, though—a shield punctured! Yes, that designer, he really should have…

He was dog-tired. Time had got completely bollixed up for him. Between Mars and Earth they must have lost a Tuesday, since it went directly from Monday to Wednesday; that meant they also missed a night. “I better stock up on some sleep,” he thought, got up, and automatically headed for the tiny bathroom. But at the memory of the icy water he shuddered, did an about-face, and a minute later was in bed. Which couldn’t hold a candle to a ship’s bunk. His hand automatically groped around for the belts to buckle down the quilt, and he gave a faint smile when he couldn’t find them; after all, he was in a hotel, not threatened by any sudden loss of gravitation.

That was his last thought. When he opened his eyes, he had no idea where he was. It was pitch-black. “Tyndall!” he wanted to shout, and all at once—for no apparent reason—remembered how once Tyndall had burst terrified out of the cabin, in nothing but pajama bottoms, and desperately cried to the man on watch, “You! For God’s sake! Quick, tell me, what’s my name?” The poor devil was plastered; he had been fretting over some imagined insult or other and had drunk an entire bottle of rum.

In this roundabout way Pirx’s mind returned to reality. He got up, turned on the light, went to take a shower, but then remembered about the water, so carefully let out first a small trickle—lukewarm; he sighed, because he yearned for a good hot bath, but after a minute or two, with the stream beating on his face and torso, he actually began to hum.

He was just putting on a clean shirt when the loudspeaker—he had no idea there was anything like that in the room—said in a deep bass:

“Attention! Attention! This is an important announcement. Will all men with military training please report immediately to Port Control, Room 318, with Commodore-Engineer Achanian. We repeat. Attention, attention…”

Pirx was so astonished, he stood there for a moment in only his socks and shirt. What was this? April Fools’ Day? “With military training”? Maybe he was still asleep. But when he flung his arms to pull the shirt on all the way, he cracked his hand against the edge of the table, and his heart beat faster. No, no dream. Then what was it? An invasion? Martians taking over the Moon? What nonsense! Whatever it was, he had to go.

But something whispered to him while he jumped into his pants, “Yes, this had to happen, because you are here. That’s your luck, old man, you bring trouble…”

As he left the room his watch said eight. He wanted to stop somewhere and ask what the hell was going on, but the corridor was empty, and so was the escalator, as though a general mobilization had already taken place and everyone was scrambling God knows where at the front line. He ran up the steps; they were moving at a good clip to begin with, but he hurried as if he actually might miss a chance at derring-do. At the top he saw a brightly lit glass kiosk with newspapers and ran up to the window to ask his question, but there was no one to ask. The papers were sold by machine.

He bought a pack of cigarettes and a daily, which he glanced at without slowing his pace; it contained nothing but an account of the meteorite disaster. Could that be it? But why military training? Impossible! Down a long corridor he went toward Port Control. Finally he saw people. Someone was entering a room with the number 318, someone else was coming up from the opposite end of the corridor.

“I won’t find out anything now; I’m too late,” he thought as he straightened his jacket and walked in. It was a small room, with three windows; behind them blazed an artificial lunar landscape, the unpleasant color of hot mercury. In the narrower part of the trapezoidal room stood two desks, the entire area in front of them being crammed with chairs, evidently brought in on short notice, since almost every chair was different. There were around fourteen or fifteen people here, mostly middle-aged men with a few kids who wore the stripes of navy cadets. Sitting apart was some elderly commodore—the rest of the chairs remained empty. Pirx took a seat next to one of the cadets, who immediately began telling him how six of them had flown in just the other day to start their apprenticeship “that side,” but they were given only a small machine, it was called a flea, and the thing barely took three, the rest had to wait their turn, then suddenly this business cropped up. Did Mr. Navigator happen to know…? But Mr. Navigator was in the dark himself. Judging by the faces of those seated, you could tell that they, too, were shocked by the announcement—they probably all came from the hotel. It must have occurred to the cadet that he ought to introduce himself, because he started going through a few gymnastics, nearly overturning his chair. Pirx grabbed it by the back, and just then the door opened and in walked a short, dark-haired man slightly gray at the temples. He was clean-shaven, but his cheeks were blue with stubble; he had beetle brows and small, piercing eyes. Without a word he passed between the chairs, and behind the desk pulled down from a reel near the ceiling a map of “that side,” on a scale of one to one million. The man rubbed his strong, fleshy nose with the back of his hand and said, without preamble:

“Gentlemen, I am Achanian. I have been temporarily delegated by the joint heads of Luna Base 1 and Luna Base 2 for the purpose of neutralizing the Setaur.”

Among the listeners there was a faint stir, but Pirx still understood nothing; he didn’t even know what the Setaur was.

“Those of you who heard the radio are aware that here”—he pointed a ruler at the regions Hypatia and Alfraganus—“a swarm of meteors fell yesterday. We will not go into the effects of the impact of the others, but one—it may well have been the largest—shattered the protective shield over storage units B-7 and R-7. In R-7 was located a consignment of Setaurs, received from Earth barely four days ago. In the bulletins it was reported that all of these met with destruction. That, gentlemen, is not the truth.”

The cadet sitting next to Pirx listened with red ears; even his mouth hung open, as if to take in every word. Meanwhile Achanian went on:

“Five of the robots were crushed beneath the falling roof, but the sixth survived. More precisely—it suffered damage. We think so for the reason that as soon as it extricated itself from the ruins of the storage unit, it began to behave in a manner … to behave like a…”

Achanian couldn’t find the right word, so without finishing his sentence he continued:

“The storage units are situated near the siding of a narrow-gauge track eight kilometers from the provisional landing field. Immediately after the disaster, a rescue operation was initiated, and the first order of business was to check out all personnel, to see if anyone had been buried beneath the devastated buildings. This action lasted about an hour; in the meantime, however, it developed that from the concussion the central administration buildings had lost their full seal, so the work dragged on till midnight. Around one o’clock it was discovered that the breakdown in the main grid supplying the entire construction site, as well as the interruption of telephone communication, had not been caused by the meteors. The cables had been cut—by laser beam.”

Pirx blinked. He couldn’t help feeling that he was participating in some sort of play, a masquerade. Such things didn’t happen. A laser! Sure! And why not throw in a Martian spy while you were at it? Yet this commodore-engineer hardly looked like the type who would get hotel guests up at the crack of dawn in order to play some stupid joke on them.

“The telephone lines were repaired first,” said Achanian. “But at that same time a small transporter from the emergency party, having reached the place where the cables were broken, lost radio contact with Luna Base. After three in the morning we learned that this transporter had been attacked by laser and, as a result of several hits, now stood in flames. The driver and his assistant perished, but two of the crew—fortunately they were in suits, having got themselves ready to go out and repair the line—managed to jump free in time and hide in the desert, that is, the Mare Tranquilitatis, roughly here…” Achanian indicated with his ruler a point on the Sea of Tranquillity, some four hundred kilometers from the little crater of Arago.

“Neither of them, as far as I know, saw the assailant. At a particular moment they simply felt a very strong thermal blast, and the transporter caught fire. They jumped before the tanks of compressed gas went off; the lack of an atmosphere saved them, since only that portion of the fuel which was able to combine with the oxygen inside the transporter exploded. One of these people later died, in as yet undetermined circumstances. The other succeeded in returning to the construction site, crossing a stretch of about one hundred forty kilometers, but he ran and exhausted his suit’s air supply and went into anoxia. Fortunately he was discovered and is now in the hospital. Our knowledge of what happened is based entirely on his account and needs further verification.”

There was a dead silence. Pirx could see where all of this was leading, but he still didn’t believe it; he didn’t want to…

“No doubt you have guessed, gentlemen,” continued the dark-haired man in an even voice—his profile stood out black as coal against the blazing mercury landscapes of the moon—“that the one who cut the telephone cables and high-tension line, and also attacked the transporter, is our sole surviving Setaur. This is a unit about which we know little; it was put into mass production only last month. Engineer Klarner, one of Setaur’s designers, was supposed to have come here with me, to give you gentlemen a full explanation not only of the capabilities of this model, but also of the measures that now must be taken to neutralize or destroy the object.” The cadet next to Pirx gave a soft moan. It was a moan of pure excitement, uttered without even the pretense of sounding horrified. The young man was not aware of the navigator’s disapproving look. But, then, no one noticed or heard anything but the voice of the commodore-engineer.

“I’m no expert in intellectronics and therefore cannot tell you much about the Setaur. But among those present, I believe, is a Dr. McCork. Is he here?”

A slender man wearing glasses stood up. “Yes. I didn’t take part in the designing of the Setaurs; I’m only acquainted with our English model, similar to the American one but not identical. Still, the differences are not so very great. I can be of help.”

“Excellent. Doctor, if you would come up here. I’ll just present, first, the current situation. The Setaur is located somewhere over here”—Achanian made a circle with the end of his ruler around an edge of the Sea of Tranquillity—“which means it is at a distance of thirty to eighty kilometers from the construction site. It was designed, as the Setaurs in general were designed, to perform mining tasks under extremely difficult conditions, at high temperatures, with a considerable chance of cave-ins; hence these models possess a massive frame and thick armor… But Dr. McCork will be filling you gentlemen in on this aspect. As for the means at our disposal to neutralize it: the headquarters of all the lunar bases have given us, first of all, a certain quantity of explosives, dynamite and oxyliquites, plus line-of-sight hand lasers and mining lasers—of course, neither the explosives nor the lasers were made for use in combat. For conveyance, the groups operating to destroy the Setaur will have transporters of small and medium range, two of which possess light anti-meteorite armor. Only such armor can take the blow of a laser from a distance of one kilometer. True, that applies to Earth, where the energy absorption coefficient of the atmosphere is an important factor. Here we have no atmosphere; therefore those two transporters will be only a little less vulnerable than the others. We are also receiving a considerable number of suits, oxygen—and that, I’m afraid, is all. Around noon there will arrive from the Soviet sector a ‘flea’ with a three-man crew; in a pinch it can hold four on short flights, to deliver them inside the area where the Setaur is located. I’ll stop here for the moment. Now, gentlemen, I would like to pass around a sheet of paper, on which I will ask you to write clearly your names and fields of competence. Meanwhile, if Dr. McCork would kindly tell us a few words about the Setaur… The most important thing, I believe, would be an indication of its Achilles’ heel…”

McCork was now standing by Achanian. He was even thinner than Pirx had thought; his ears stuck out, his head was slightly triangular, he had almost invisible eyebrows, a shock of hair of indeterminate color, and all in all seemed strangely likable.

Before he spoke, he took off his steel-rimmed glasses, as if they were in the way, and put them on the desk.

“I’d be lying if I said we had allowed for the possibility of the kind of thing that’s happened here. But besides the mathematics, a cyberneticist has to have in his head some grain of intuition. It was precisely for this reason that we decided not to put our model into mass production just yet. According to the laboratory tests, Mephisto works perfectly—that’s the name of our model. And Setaur is supposed to have better stabilization for braking and activating. Or so I thought, going by the literature—now I’m not so sure,

“The name suggests mythology, but it’s only an acronym, from Self-programming Electronic Ternary Automaton Racemic, racemic since in the construction of its brain we use both dextro- and levorotatory monopolymer pseudo crystals. But I guess that’s not important here. It is an automaton equipped with a laser for mining operations, a violet laser; the energy to emit the impulses is supplied it by a micropile, working on the principle of a cold chain reaction, so that the Setaur—if I remember correctly—can put out impulses of up to forty-five thousand kilowatts.”

“For how long?” someone asked.

“From our point of view, forever,” immediately replied the thin scientist. “In any case for many years. What exactly happened to this Setaur? In plain language, I think it got hit over the head. The blow must have been unusually strong, but, then, even here a falling building could damage a chromium-nickel skull. So what took place? We’ve never conducted experiments of this kind; the cost would be too great”—McCork gave an unexpected smile, showing small, even teeth—“but it is generally known that any sharply localized damage to a small, that is, relatively simple, brain or ordinary computer results in a complete breakdown in function. However, the more we approximate the human brain by imitating its processes, then the greater the degree to which such a complex brain will be able to function despite the partial damage it has suffered. The animal brain—a cat’s brain, for example—contains certain centers, the stimulation of which produces an attack response, manifested as an outburst of aggressive rage. The brain of the Setaur is built differently, yet does possess a certain general drive, a potentiality for action, which can be directed and channeled in various ways. Now, some sort of short circuit occurred between that motive center and an already initiated program for destruction. Of course I am speaking in grossly oversimplified terms.”

“But why destruction?” asked the same voice as before.

“It is an automaton designed for mining operations,” Dr. McCork explained. “Its task was to have been to dig levels or drifts, to bore through rock, to crush particularly hard minerals—broadly speaking, to destroy cohesive matter, obviously not everywhere and not everything, but as a result of its injury such a generalization came about. Anyway, my hypothesis could be completely wrong. That side of the question, the purely theoretical, will be worth considering later, after we have made a carpet of the thing. At present it is more important for us to know what the Setaur can do. It can move at a speed of about fifty kilometers an hour, over almost any terrain. It has no lubricating points; all the friction-joint surfaces work on teflon. Its suspensions are magnetic, its armor cannot be penetrated by any revolver or rifle bullet. Such tests have not actually been made, but I think that possibly an antitank gun… Of course, we don’t have any of those, do we?”

Achanian shook his head. He picked up the list that had been returned to him and read it, making little marks beside the names.

“Obviously, the explosion of a fair-sized charge would pull it apart,” McCork went on calmly, as if he were talking about the most ordinary things. “But first you would have to bring the charge near it, and that, I am afraid, will not be easy.”

“Where exactly does it have its laser? In the head?” asked someone from the audience.

“Actually it has no head, only a sort of bulge, a swelling between the shoulders. That was to increase its resistance to falling rock. The Setaur measures two hundred twenty centimeters in height, so it fires from a point about two meters above the ground; the muzzle of the laser is protected by a sliding visor; when the body is stationary it can fire through an angle of thirty degrees, and a greater field of aim is obtained when the entire body turns. The laser, as I said, has a maximum power of forty-five thousand kilowatts. Any expert will realize that this is considerable; it can easily cut through a steel plate several centimeters thick…”

“At what range?”

“It’s a violet laser, therefore with a very small angle of divergence from the line of incidence. So the range will be, for all practical purposes, limited to the field of vision; since the horizon here on a level plane is at a distance of two kilometers, two kilometers at the very least will be the range of fire.”

“We will be receiving special mining lasers of six times that power,” Achanian put in.

“But that is only what the Americans call overkill,” McCork replied with a smile. “Such power will provide no advantage in a duel with the Setaur’s laser.”

Someone asked whether it wouldn’t be possible to destroy the automaton from aboard some cosmic vessel. McCork declared himself not qualified to answer; Achanian meanwhile glanced at the sign-up sheet and said:

“We have here a navigator first class. Pirx … would you care to comment on this?”

Pirx got up.

“Well, in theory, a vessel of medium tonnage like my Cuivier, which has a sixteen-thousand-ton rest mass, could certainly destroy such a Setaur, if it got it in its line of thrust. The temperature of the exhaust gases exceeds six thousand degrees for a distance of nine hundred meters. That would be sufficient, I think…?”

McCork nodded.

“But this is sheer speculation,” Pirx continued. “The vessel would have to be somehow brought into position, and a small target like the Setaur, which really isn’t any larger than a man, could always have time to move out of the way, unless it were immobilized. The lateral velocity of a vessel maneuvering near the surface of a planet, within its field of gravity, is quite small; sudden pursuit maneuvers are completely out of the question. The only remaining possibility, then, would be to use small units, say, the Moon’s own fleet. Except that the thrust here would be weak and of not very high temperature, so perhaps if you used one of those crafts as a bomber instead… But for precision bombing you need special instruments, sights, range-finders, which Luna Base doesn’t have. No, we can rule that out. Of course it will be necessary, even imperative, to employ such small machines, but only for reconnaissance purposes—that is, to pinpoint the automaton.”

He was about to sit down when suddenly a new idea hit him.

“Oh, yes!” he said. “Jump holsters. Those you could use. I mean—you would have to have people who knew how to use them.”

“Are they the small, individual rockets one straps on over the shoulders?” asked McCork.

“Yes. With them you can execute jumps or even sail along without moving; depending on the model and type, you get from one to several minutes aloft and reach an altitude of fifty to four hundred meters.”

Achanian stood.

“This may be important. Who here has been trained in the use of such devices?”

Two hands went up. Then another.

“Only three?” said Achanian, “Ah; you, too?” he added, seeing that Pirx, who now saw what was coming, had also raised his hand. “That makes four. Not very many… Well ask among the ground crew. Gentlemen! This is—it goes without saying—strictly a voluntary mission. I really ought to have begun with that. Who wants to take part in the operation?”

A slight clatter ensued, for everyone present was standing up.

“On behalf of Control, I thank you,” said Achanian. “This is fine… And so we have seventeen volunteers. We will be supported by three units from the lunar fleet, and in addition will have at our disposal ten drivers and radio operators to help man the transporters. I will ask you all to remain here, and you”—he turned to McCork and Pirx—“please come with me, to Control.”

Around four in the afternoon Pirx was sitting in the turret of a large caterpillar transporter, jolted by its violent motions. He was wearing a full suit, with the helmet on his knees, ready to put it on at the first sound of the alarm, and across his chest hung a heavy laser, the butt of which poked him unmercifully; in his left hand he had a map, and he used the right to turn a periscope, observing the long, spread-out line of the other transporters, which pitched and tossed like boats across the debris-strewn tracts of the Sea of Tranquillity. That desert “sea” was all ablaze with sunlight and empty from one black horizon to the other. Pirx received reports and passed them on, spoke with Luna Base 1, with the officers of the other machines, with the pilots of the reconnaissance modules, whose microscopic exhaust flames every so often appeared among the stars in the black sky; yet with all of this he still couldn’t help feeling at times that he was having some kind of highly elaborate and silly dream.

Things had happened with increasing frenzy. He wasn’t the only one to whom it seemed that Construction had succumbed to something like panic. For, really, what could one halfwit automaton do, even armed with a light-thrower? So when at the second “summit meeting,” right at noon, there began to be talk of turning to the UN, at least to the Security Council, for “special sanction,” namely permission to bring in heavy artillery (rocket launchers would be best), and possibly even atomic missiles—Pirx objected, along with others, that in that way, before they got anywhere, they would be making complete asses of themselves in front of all Earth. Besides, it was obvious that for such a decision from the international body they would have to wait days if not weeks, and meanwhile the “mad robot” could wander off God knows where. Once it was hidden in the inaccessible rifts of the lunar crust, you wouldn’t be able to get at it with all the cannons in the world; it was essential to act decisively and without delay.

It became clear then that the biggest problem would be communications, which had always been a sore point in lunar undertakings. Supposedly, there existed about three thousand different patents for inventions designed to facilitate communications, ranging from a seismic telegraph (using microexplosions as signals) to “Trojans,” stationary satellites. Such satellites had been placed in orbit last year, but they didn’t improve the situation one bit. In practice the problem was solved by systems of ultrashortwave relays set on poles, a lot like the old pre-Sputnik television transmission lines on Earth. This was actually more reliable than communication by satellite, because the engineers were still racking their brains over how to make their orbiting stations unsusceptible to solar storms. Every single jump in the activity of the sun, and the resultant “hurricanes” of electrically charged high-energy particles that tore through the ether, immediately produced a static that made it difficult to maintain contact—sometimes for several days.

One of those solar “twisters” was going on right now, so messages between Luna Base 1 and Construction went by way of the ground relays, and the success of Operation Setaur depended—to a large degree, at least—on the “rebel’s” not taking it into its head to destroy the girdered poles that stood, forty-five of them, on the desert separating Luna City from the cosmodrome near the construction site. Assuming, of course, that the automaton would continue to prowl in that vicinity. It had, after all, complete freedom of movement, requiring neither fuel nor oxygen, neither sleep nor rest; in all, it was so self-sufficient that many of the engineers for the first time fully realized how perfect was this machine of their own making—a machine whose next step no one could foresee.

The direct Moon-Earth discussions which had begun at dawn between Control and the firm Cybertronics, including the staff of Setaur’s designers, went on and on; but not a thing was learned from them that hadn’t already been said by little Dr. McCork. It was only the laymen who were still trying to talk the specialists into using some great calculator to predict the automaton’s tactics. Was the Setaur intelligent? Well, yes, in its own fashion. That “unnecessary”—and at the present moment highly dangerous—“wisdom” of the machine angered many participants in the action; they couldn’t see why in hell the engineers had bestowed such freedom and autonomy on a machine made strictly for mining tasks. McCork calmly explained that this “intellectronic redundancy” was, in the current phase of technological development, the same thing as the excess of power generally found in all conventional machines and engines: it was an emergency reserve, put there in order to increase safety and dependability of function. There was no way of knowing in advance all the situations in which a machine, be it mechanical or informational, might find itself. And therefore no one really had the foggiest notion of what the Setaur would do. Of course the experts, including those on Earth, had telegraphed their opinions; the only problem was that these opinions were diametrically opposed. Some believed the Setaur would attempt to destroy objects of an “artificial” nature, precisely like the relay poles or high-tension lines; others thought, on the contrary, that it would expend its energy by firing at whatever stood in its path, whether a lunar rock or a transporter filled with people. The former were in favor of an immediate attack for the purpose of destroying it; the latter recommended a wait-and-see strategy. Both were in agreement on one thing only, that it was absolutely vital to keep track of the machine’s movements.

Since early morning the lunar fleet, numbering twelve small units, had patrolled the Sea of Tranquillity and sent continual reports to the group defending the construction site, which in turn was in constant contact with headquarters at the cosmodrome. It was no easy thing to detect the Setaur, a tiny piece of metal in a giant wilderness of rock filled with fields of detritus, cracks, and half-buried crevices, and covered besides with the pockmarks of miniature craters.

If only those reports had at least been negative! But the patrolling crews had alarmed ground personnel several times already with the information that the “mad machine” was sighted. So far it had turned out that the object was some unusual rock formation or a fragment of lava sparkling in the rays of the sun; even the use of radar along with ferroinduction sensors proved to be of little help—in the wake of the first stages of lunar exploration and colonization, there remained upon the Moon’s rocky wastes a whole multitude of metal containers, heat-fused shells from rocket cartridges, and all possible sorts of tin junk, which every now and then became the source of fresh alarms. So much so that operation headquarters began to wish the Setaur would finally attack something and show itself. However, the last time it had revealed its presence was with the attack on the small transporter belonging to the electrical repair team. Since then it seemed as if the lunar soil had opened up and swallowed the thing. But everyone felt that sitting and waiting was out of the question, particularly when Construction had to regain its energy supply.

The mission—covering about ten thousand square kilometers—consisted in combing that area with two waves of vehicles approaching each other from opposite directions, from the north and the south. From Construction came one extended line under the command of their head technologist, Strzibor, and from the Luna Base cosmodrome came the second, in which the role of operations coordinator of both sides, working closely with the chief (Commodore-Navigator Pleydar), fell to Pirx. He understood perfectly that at any moment they could pass right by the Setaur; it might, for example, be hidden in one of those deep tectonic trenches, or even be camouflaged by nothing but the dazzling lunar sand, and they would never notice it; McCork, who rode with him as “intellectronician-consultant,” was of the same opinion.

The transporter lurched dreadfully, moving along at a speed that, as the driver quietly informed them, “after a while makes your eyes pop out.” They were now in the eastern sector of the Sea of Tranquillity and less than an hour away from the region where the automaton was most likely to be located. After crossing that previously determined border, they were all to don their helmets, so that in case of an unexpected hit and loss of seal, or in case of fire, they could leave the vehicle immediately.

The transporter had been changed into a fighting machine; the mechanics had mounted on its domelike turret a mining laser of great power, though pretty poor as far as accuracy went. Pirx considered it altogether useless against the Setaur. The Setaur possessed an automatic sighter, since its photoelectric eyes were hooked up directly to the laser and it could instantly fire at whatever lay in the center of its field of vision. Theirs, on the other hand, was a quaint sort of sighter, probably from an old cosmonautical range-finder; the only testing it had received was when, before leaving Luna Base, they took a few shots at some rocks on the horizon. The rocks had been large, the distance less than two kilometers, and even so they hit the mark only on the fourth try. And here, to make matters worse, you had lunar conditions to cope with, because a laser beam was visible as a brilliant streak only in a diffusing medium, such as an Earthlike atmosphere; but in empty space a beam of light, regardless of how powerful, was invisible until it hit some material obstacle. Therefore, on Earth you could shoot a laser much the way you shot tracer bullets, guided by their observable line of flight. Without a sighter, a laser on the Moon was of no practical value. Pirx didn’t keep this from McCork; he told him when only a couple of minutes separated them from the hypothetical danger zone.

“I didn’t think of that,” said the engineer, then added, with a smile, “Why did you tell me?”

“To free you of illusions,” replied Pirx, not looking up from the double eyepiece of his periscope. It had foam-rubber cushions, but he felt sure that he would be going around with black eyes for the longest time (assuming, of course, he came out of this alive). “And also to explain why we’re carrying that stuff in the back.”

“The cylinders?” asked McCork. “I saw you taking them from the storeroom. What’s in them?”

“Ammonia, chlorine, and some hydrocarbons or other,” said Pirx. “I though they might come in handy.”

“A gas smoke-screen?” ventured the engineer.

“No, what I had in mind was some way of aiming. If there’s no atmosphere, we create one, at least temporarily…”

“I’m afraid there won’t be time for that.”

“Perhaps not, but I brought it along just in case. Against something insane, insane measures are often best.”

They fell silent, for the transporter had begun to lurch like a drunk; the stabilizers whined and squealed, sounding as if at any minute the oil in them would begin to boil. They hurtled down an incline strewn with sharp boulders. The opposite slope gleamed, all white with pumice.

“You know what worries me most?” resumed Pirx when the heaving let up a little; he had grown strangely talkative. “Not the Setaur—not at all—it’s those transporters from Construction. If just one of them takes us for the Setaur and starts blasting away with its laser, things’ll get lively.”

“I see you’ve thought of everything,” muttered the engineer. The cadet, sitting beside the radio operator, leaned across the back of his seat and handed Pirx a scrawled radiogram, barely legible.

“We have entered the danger zone at relay twenty, so far nothing, stop, Strzibor, end of transmission,” Pirx read aloud. “Well, we’ll soon have to put our helmets on, too…”

The machine slowed a little, climbing a slope. Pirx noticed that he could no longer see the neighbor on his left—only the right-hand transporter was still visible, moving like a dim blot up the bank. He ordered that the machine on the left be raised on the radio, but there was no answer.

“We have begun to separate,” he said calmly. “I thought that would happen. Can’t we push the antenna up a little higher? No? Too bad.”

By now they were at the summit of a gentle rise. From over the horizon, at a distance of less than two hundred kilometers, emerged, full in the sun, the sawtooth ridge of the crater Toricelli, sharply outlined against the black background of the sky. They had the plain of the Sea of Tranquillity all but behind them now. Deep tectonic rifts appeared, frozen slabs of magma jutted here and there from under the debris, and over these the transporter crawled with difficulty, first heaving up like a boat on a wave, then dropping heavily down, as though it were about to plunge head over heels into some unknown cavity. Pirx caught sight of the mast of the next relay, glanced quickly at the celluloid map card pressed to his knees, and ordered everyone to fasten their helmets. From now on they would be able to communicate only by intercom. The transporter managed to shake even more violently than before—Pirx’s head wobbled around in its helmet like the kernel of a nut inside an otherwise empty shell.

When they drove down the slope to lower ground, the saw of Toricelli disappeared, blocked out by nearer elevations; almost at the same time they lost their right neighbor. For a few minutes more they heard its call signal, but then that was distorted by the waves bouncing off the sheets of rock. Complete radio silence followed. It was extremely awkward trying to look through the periscope with a helmet on; Pirx thought he would either crack his viewplate or smash the eyepiece. He did what he could to keep his eyes on the field of vision at all times, though it shifted drastically with each lurch of the machine and was strewn with endless boulders. The jumble of pitch-black shadow and dazzlingly bright surfaces of stone made his eyes swim.

Suddenly a small orange flame leaped up in the darkness of the far sky, flickered, dwindled, disappeared. A second flash, a little stronger. Pirx shouted, “Attention everyone! I see explosions!” and feverishly turned the crank of the periscope, reading the azimuth off the scale etched on the lenses.

“We’re changing course!” he howled. “Forty-seven point eight, full speed ahead!”

The terms of this order really applied to a cosmic vessel, but the driver understood it all the same; the plates and every joint of the transporter gave a shudder as the machine wheeled around practically in place and surged forward. Pirx got up from his seat: its tossing was pulling his head away from the eyepiece. Another flash—this time red-violet, a fan-shaped burst of flame. But the source of those flashes or explosions lay beyond the field of vision, hidden by the ridge they were climbing.

“Attention everyone!” said Pirx. “Prepare your individual lasers! Dr. McCork, please go to the hatch. When I give the word, or in case of a hit, you’ll open it! Driver! Decrease velocity!”

The elevation up which the machine was clambering rose from the desert like the shank of some moon monster, half sunken in debris; the rock in fact resembled, in its smoothness, a polished skeleton or giant skull; Pirx ordered the driver to go to the top. The treads began to chatter, like steel over glass. “Hold it!” yelled Pirx, and the transporter, coming to a sudden halt, dipped nose-down toward the rock, swayed as the stabilizers groaned with the strain, and stopped.

Pirx looked into a shallow basin enclosed on two sides by radially spreading, tapered embankments of old magma flows; two-thirds of the wide depression lay in glaring sun, a third was covered by a shroud of absolute black. On that velvet darkness there shone, like a weird jewel, fading ruby-red, the ripped-open skeleton of a vehicle. Besides Pirx, only the driver saw it, for the armor flaps of the windows had been lowered. Pirx, to tell the truth, didn’t know what to do. “A transporter,” he thought. “Where is the front of it? Coming from the south? Probably from the construction group, then. But who got it, the Setaur? And I’m standing here in full view, like an idiot—we have to conceal ourselves. But where are all the other transporters? Theirs and mine?”

“I have something!” shouted the radiotelegraph man. He connected his receiver to the inside circuit, so that they could all hear the signals in their helmets.

“Aximo-portable talus! A wall with encystation—repetition from the headland unnecessary—the access at an azimuth of—multicrystalline metamorphism…” The voice filled Pirx’s earphones, delivering the words clearly, in a monotone, with no inflection whatever.

“It’s him!” he yelled. “The Setaur! Hello, radio! Get a fix on that, quickly! We need a fix! For God’s sake! While it’s still sending!” He roared till he was deafened by his own shouts amplified in the closed space of the helmet; not waiting for the telegraph operator to snap out of it, he leaped, head bowed, to the top of the turret, seized the double handgrip of the heavy laser, and began turning it along with the turret, his eyes already at the sighter. Meanwhile, inside his helmet, that low, almost sorrowful, steady voice droned on:

“Heavily bihedrous achromatism viscosity—undecorticated segments without repeated anticlinal interpolations”—and the senseless gabble seemed to weaken.

“Where’s that fix, damn it?!!”

Pirx, keeping his eyes glued to the sighter, heard a faint clatter—McCork had run up front and shoved aside the operator; there was a sound of scuffling…

Suddenly in his earphones he heard the calm voice of the cyberneticist:

“Azimuth 39.9 … 40.0 … 40.1 … 40.2…”

“It’s moving!” Pirx realized. The turret had to be turned by crank; he nearly dislocated his arm, he cranked so hard. The numbers moved at a creep. The red line passed the 40 mark.

Suddenly the voice of the Setaur rose to a drawn-out screech and broke off. At that same moment Pirx pressed the trigger, and half a kilometer down, right at the line between light and shadow, a rock spouted fire brighter than the sun.

Through the thick gloves it was next to impossible to hold the handgrip steady. The blinding flame bored into the darkness at the bottom of the basin; a few dozen meters from the dimly glowing wreck, it stopped and, in a spray of jagged embers, cut a line sideways, twice raising columns of sparks. Something yammered in the earphones. Pirx paid no attention, just plowed on with that line of flame, so thin and so terrible, until it split into a thousand centrifugal ricochets off some stone pillar. Red swirling circles danced before him, but through their swirl he saw a bright blue eye, smaller than the head of a pin, which had opened at the very bottom of the darkness, off to the side somewhere, not where he had been shooting—and before he was able to move the handgrip of the laser, to pivot it around on its swivel, a rock right next to the machine itself exploded like a liquid sun.

“Back!” he bellowed, ducking by reflex, with the result that he no longer saw anything; but he wouldn’t have seen anything anyway, only those red, slowly fading circles, which turned now black, now golden.

The engine thundered. They were thrown with such violence that Pirx fell all the way to the bottom, then flew to the front, between the knees of the cadet and the radio operator; the cylinders, though they had tied them down securely on the armored wall, made an awful racket. They were rushing backward, in reverse, there was a horrible crunch beneath the tractor tread, they swerved, careened in the other direction, for a minute it looked like the transporter was going to flip over on its back… The driver, desperately working the gas, the brakes, the clutch, somehow brought that wild skid under control; the machine gave a long quiver and stood still.

“Do we have a seal?” shouted Pirx, picking himself up off the floor. “A good thing it’s rubber,” he managed to think.

“Intact!”

“Well, that was nice and close,” he said in an altogether different voice now, standing up and straightening his back. And added softly, not without chagrin: “Two hundredths more to the left and I would have had him.”

McCork returned to his place.

“Doctor, that was good, thank you!” called Pirx, already back at the periscope. “Hello, driver, let’s go down the same way we came up. There are some small cliffs over there, a kind of arch—that’s it, right!—drive into the shadow between them and stop.”

Slowly, as if with exaggerated caution, the transporter moved in between the slabs of rock half buried in sand and froze in their shadow, which would render it invisible.

“Excellent!” said Pirx almost cheerfully. “Now I need two men to go with me and do a little reconnoitering…”

McCork raised his hand at the same time as the cadet.

“Good! Now listen; you”—he turned to the others—“will remain here. Don’t move out of the shadow, even if the Setaur should come straight at you—sit quietly. Well, I guess if it walks right into the transporter, then you’ll have to defend yourselves; you have the laser. But that’s not very likely. You,” he said to the driver, “will help this young man remove those cylinders of gas from the wall, and you”—this to the radio operator—“will call Luna Base, the cosmodrome, Construction, the patrols, and tell the first who answers that it destroyed one transporter, probably belonging to Construction, and that three men from our machine have gone out to hunt it. So I don’t want anybody barging in with lasers, shooting blindly, and so on… And now let’s go!”

Since each of them could carry only one cylinder, the driver accompanied them and they took four. Pirx led his companions not to the top of the “skull,” but a little beyond, where a small, shallow ravine could be seen. They went as far as they could and set the cylinders down by a large boulder; Pirx ordered the driver to go back. He himself peered out over the surface of the boulder and trained his binoculars on the interior of the basin. McCork and the cadet crouched down beside him. After a long while he said:

“I don’t see him. Doctor, what the Setaur said, did it have any meaning?”

“I doubt it. Combinations of words—a sort of schizophrenic thing.”

“That wreck has had it,” said Pirx.

“Why did you shoot?” asked McCork. “There might have been people.”

“There wasn’t anyone.”

Pirx moved the binoculars a millimeter at a time, scrutinizing every crease and crevice of the sunlit area.

“They didn’t have time to jump.”

“How do you know that?”

“Because he cut the machine in half. You can still see it. They must have practically run into him. He hit from a few dozen meters. And besides, both hatches are closed. No,” he added after a couple of seconds, “he’s not in the sun. And probably hasn’t had a chance to sneak away. We’ll try drawing him out.”

Bending over, he lifted a heavy cylinder to the top of the boulder and, shoving it into position before him, muttered between his teeth:

“A real live cowboys-and-Indians situation, the kind I always dreamed of…”

The cylinder slipped; he held it by the valves and, flattening himself out on the stones, said:

“If you see a blue flash, shoot at once—that’s his laser eye.”

With all his might he pushed the cylinder, which, at first slowly but then with increasing speed, began to roll down the slope. All three of them took aim; the cylinder had now gone about two hundred meters and was rolling more slowly, for the slope lessened. A few times it seemed that protruding rocks would bring it to a stop, but it tumbled past them and, growing smaller and smaller, now a dully shining spot, approached the bottom of the basin.

“Nothing?” said Pirx, disappointed. “Either he’s smarter than I thought, or he just isn’t interested in it, or else…”

He didn’t finish. On the slope below them there was a blinding flash. The flame almost instantly changed into a heavy, brownish-yellow cloud, at the center of which still glowed a sullen fire, and the edges spread out between the spurs of rock.

“The chlorine…” said Pirx. “Why didn’t you shoot? Couldn’t you see anything?”

“No,” replied the cadet and McCork in unison.

“The bastard! He’s hid himself in some crevice or is firing from the flank. I really doubt now that this will do any good, but let’s try.”

He picked up a second cylinder and sent it after the first.

At first it rolled like the other one, but somewhere about halfway down the incline it turned aside and came to rest. Pirx wasn’t looking at it—all his attention was concentrated on the triangular section of darkness in which the Setaur must be lurking. The seconds went by slowly. All at once a branching explosion ripped the slope. Pirx was unable to locate the place where the automaton had concealed itself, but he saw the line of fire, or more precisely a part of it, for it materialized as a burning, sunbright thread when it passed through what was left of the first cloud of gas. Immediately he sighted along that gleaming trajectory, which was already fading, and as soon as he had the edge of the darkness in his cross hairs, he pulled the trigger. Apparently McCork had done the same thing simultaneously, and in an instant the cadet joined them. Three blades of sun plowed the black floor of the basin and at that very moment it was as if some gigantic, fiery lid slammed down directly in front of them—the entire boulder that protected them shook, from its rim showered a myriad searing rainbows, their suits and helmets were sprayed with burning quartz, which instantly congealed to microscopic teardrops. They lay now flattened in the shadow of the rock, while above their heads whipped, like a white-hot sword, a second and a third discharge, grazing the surface of the boulder, which immediately was covered with cooling glass bubbles.

“Everyone all right?” asked Pirx, not lifting his head.

“Yes!”—“Here, too!”—came the answers.

“Go down to the machine and tell the radio operator to call everyone, because we have him here and will try to keep him pinned as long as possible,” Pirx said to the cadet, who then crawled backward and ran, stooping, in the direction of the rocks where the tractor was standing.

“We have two cylinders left, one apiece. Doctor, let’s switch positions now. And please be careful and keep low; he’s already hit right on top of us…”

With these words Pirx picked up one cylinder and, taking advantage of the shadows thrown by some large stone slabs, moved forward as quickly as he could. About two hundred steps farther on, they rested in the cleft of a magma embankment. The cadet, returning from the transporter, wasn’t able to find them at first. He was breathing hard, as if he had run at least a few kilometers.

“Easy, take your time!” said Pirx. “Well, what’s up?”

“Contact has been resumed.” The cadet squatted by Pirx, who could see the youth’s eyes blinking behind the viewplate of his helmet. “In that machine, the one that was destroyed … there were four people from Construction. The second transporter must have withdrawn, because it had a defective laser … and the rest went by, off to the side, and didn’t see anything…” Pirx nodded as if to say, “I thought as much.”

“What else? Where’s our group?”

“Practically all of them—thirty kilometers from here, there was a false alarm there, some rocket patrol said it saw the Setaur and pulled everyone to the spot. And three machines don’t answer.”

“When will they get here?”

“At the moment we’re only receiving…” said the cadet, embarrassed.

“Only receiving? What do you mean?”

“The radio operator says that either something’s happened to the transmitter, or else in this place his emission is damping out. He asks if he might change the parking location, so he can test…”

“He can change his location if he has to,” Pirx replied. “And please stop running like that! Watch where you put your feet!”

But the other must not have heard, for he was racing back.

“At best they’ll be here in half an hour, if we succeed in making contact,” observed Pirx. McCork said nothing. Pirx pondered the next move. Should they wait or not? Storming the basin with transporters would probably ensure success, but not without losses. Compared with the Setaur their machines made large targets, were slow, and would have to strike together, for a duel would end as it had with that tractor from Construction. He tried to come up with some stratagem to lure the Setaur out into the lighted area. If it were possible to send in one unmanned, remote-control transporter as a decoy, then hit the automaton from elsewhere—say, from above…

It occurred to him that he really didn’t have to wait for anyone; he already had one transporter. But somehow the plan didn’t hold together. To send a machine out blindly like that wouldn’t be any good. He would just blow the thing to bits, and wouldn’t have to move to do it. Could he have possibly realized that the zone of shadow in which he stood was giving him so much of an advantage? But this was not a machine created for battle with all its tactics. There was method in his madness, yes, but what method?

They sat, bent over, at the foot of a rocky scarp, in its dense, cold shadow. Suddenly it struck Pirx that he was acting like a complete idiot. What would he do, after all, if he were the Setaur? Immediately he felt alarm, for he was certain that he—in his place—would attack. Passively waiting for things to happen gained nothing. So, then, could he be advancing toward them? Even now? One could surely reach the western cliff, moving under cover of darkness the whole time, and farther on there were so many huge boulders, so much fissured lava, that in that labyrinth one could hide for God knows how long…

He was almost positive now that the Setaur would proceed in precisely this way, and that they could expect him at any moment.

“Doctor, I fear he will take us by surprise,” he said quickly, jumping to his feet. “What do you think?”

“You believe he might sneak up on us?” asked McCork and smiled. “That occurred to me, too. Well, yes, it’s even logical, but will he behave logically? That is the question.”

“We’ll try it one more time,” Pirx muttered. “We have to roll these cylinders down the hill and see what he does.”

“I understand. Now?”

“Yes. And be careful!”

They dragged the cylinders to the top of the rise and, doing their best to remain unseen from the bottom of the basin, pushed both practically at the same time. Unfortunately, the absence of air kept them from hearing whether the things were rolling, or in what way. Pirx made up his mind and—feeling strangely naked, as though there were no steel sphere over his head, nor a heavy three-layered suit covering his body—he pressed himself flat against the rock and cautiously stuck out his head.

Nothing had changed below. Except that the wrecked machine had ceased to be visible, for its cooling fragments merged with the surrounding darkness. The shadow occupied the same area, the shape of an irregular, elongated triangle, its base abutting the cliffs of the highest, western ridge of rocks. One cylinder had stopped some thirty meters beneath them, having struck a stone that put it in a lengthwise position. The other was still rolling, slowing down, growing smaller, till it stood still. Pirx was not at all pleased that nothing more happened. “He isn’t stupid,” he thought. “He won’t shoot at a target someone sticks under his nose.” He tried to find the place from which the Setaur, some ten minutes before, had betrayed itself with the flash of its laser eye, but that was extremely difficult.

“Perhaps he’s not there anymore,” Pirx reflected. “Perhaps he’s simply retreating to the north; or going parallel, along the bottom of the basin, or along one of those rifts of magnetic course… If he makes it to the cliffs, to that labyrinth, then we’ve lost him for good…”

Slowly, groping, he raised the butt of his laser and loosened his muscles. “Dr. McCork!” he said. “Could you come here?”

And when the doctor had scrambled up to him, he said:

“You see the two cylinders? One straight ahead, below us, and the other farther on?”

“I see them.”

“Fire at the closer one first, then at the other, in an interval, say, of forty seconds… But not from here!” he added quickly. “You’ll have to find a better place. Ah!” He pointed with his hand. “There is not a bad position, in that hollow. And after you shoot, crawl back immediately. All right?”

McCork asked no questions but set off at once, keeping low, in the direction indicated. Pirx waited impatiently. If he was even a little like a man, he had to be curious. Every intelligent creature was curious—and curiosity prompted it to act when something incomprehensible took place… He couldn’t see the doctor now. He forced himself not to look at the cylinders, which were to explode under McCork’s shots; he focused all his attention on the stretch of sunlit debris between the zone of shadow and the outcrop. He lifted the binoculars to his eyes and trained them on that section of the lava flow. In the lenses grotesque shapes filed slowly by, shapes as though formed in the studio of some sculptor-abstractionist; tapering obelisks twisted about like screws, plates furrowed with snaking cracks—the jumble of glaring planes and zigzag shadows had an irritating effect on the eye.

At the very edge of his vision, far below him, on the slope, there was a burgeoning flash. After a long pause, the second went off. Silence. The only sound was his pulse throbbing inside his helmet, through which the sun was trying to bore its way into his skull. He swept the lenses along a stretch of chaotically interlocking masses.

Something moved. He froze. Above the razorlike edge of a slab that resembled the fractured blade of some giant stone ax there emerged a shape, hemispherical, in color much like a dark rock, but this shape had arms, which took hold of the boulder from both sides. Now he could see it—the upper half of it. It didn’t look headless, but, rather, like a man wearing the supernatural mask of an African shaman, a mask that covered the face, neck, and chest, but flattened out in a manner that was somewhat monstrous. With the elbow of his right arm Pirx felt the butt of his laser, but he didn’t dream of shooting now. The risk was too great—the chance of getting a hit with a relatively weak weapon, and at such a distance, was minuscule. The other, motionless, seemed to be examining with that head it had, which barely protruded above the shoulders, the remains of the two gas clouds that were drifting along the slope, helplessly expanding into space. This lasted a good while. It looked as if it did not know what had happened, and was unsure of what to do. In that hesitation, that uncertainty, which Pirx could understand full well, there was something so uncannily familiar, so human, that he felt a lump in his throat. What would I do in his place, what would I think? That someone was firing at the very same objects I had fired at before, and therefore this someone would be not an opponent, not an enemy, but instead a kind of ally. But I would know, surely, that I had no ally. Ah, but what if it were a being like myself?

The other stirred. Its movements were fluid and uncommonly swift. All at once it was in full view, erect on that upended stone, as though still looking for the mysterious cause of the two explosions. Then it turned away, jumped down, and, leaning slightly forward, began to run—now and then it dropped from Pirx’s sight, but never for more than a few seconds, only to break out into the sunlight again on one of the spurs of the magma labyrinth. In this way it approached Pirx, though running the whole time at the bottom of the basin. They were separated now only by the space of the slope, and Pirx wondered whether he shouldn’t shoot, after all. But the other whisked past in narrow strips of light and again dissolved into the blackness—and since it continually had to change direction, picking its way between the rocks and rubble, one could not predict where its arms, working to maintain balance like those of a man running, and where its headless trunk would show up next, to flash metallically and vanish once again.

Suddenly ragged lightning cut across the mosaic of debris, striking long plumes of sparks among the very blocks where the Setaur was running. Who had fired that? Pirx couldn’t see McCork, but the line of fire had come from the opposite side—it could only have been the cadet, that snot-nosed kid, that idiot! He cursed him, furious, because nothing had been accomplished, of course—the dome of metal flitted on for another fraction of a second, then disappeared for good. “And not only that, but he tried to shoot him in the back!” thought Pirx in a fury, not at all appreciating the absurdity of this reproach.

The Setaur hadn’t returned fire. Why? Pirx tried to catch a glimpse of it—in vain. Could the bulge of the slope be in the way? That was entirely possible… In which case he could move safely now… Pirx slipped down from his boulder, seeing that nothing was any longer watching from below. He ran, hunched over slightly, along the rim itself; he passed the cadet, who lay prone as if on a rifle range—feet flung-out wide and pressed sideways against the rock—and Pirx felt an unaccountable urge to kick him in his behind, which stuck up ludicrously and was male even more conspicuous by a poorly fitting suit. He slowed down, but only to shout:

“Don’t you dare shoot, do you hear me? Put away that laser!”

And before the cadet, turning on his side, began to look around in bewilderment—for the voice had come from his earphones, giving no indication of where Pirx was located—Pirx had already run on; afraid that he was wasting precious time, he hurried as much as he could, till he found himself facing a broad crevasse, which opened up a sudden view all the way to the bottom of the basin.

It was a type of tectonic trench, so old that its edges had crumbled, lost their sharpness, and resembled a mountain gully widened by erosion. He hesitated. He didn’t see the Setaur, but, then, it was probably impossible to see it anyway from this vantage point. So he ventured into the gully with laser at the ready, well aware that what he was doing was insane, yet unable to resist whatever was driving him; he told himself that he only wanted to take a look, that he would stop at the first place where he could check out the last section of the outcrop and the entire labyrinth of rubble beneath it; and perhaps, even as he ran, still leaning forward, with the gravel shooting out in streams from under his boots, he actually believed this. But at the moment he couldn’t give thought to anything. He was on the Moon and therefore weighed barely fifteen kilograms, but even so the increasing angle tripped him up; he went bounding along eight meters at a time, braking for all he was worth; already he had covered half the length of the slope.

The gully ended in a shallow pathway—there in the sun stood the first masses of the lava flow, black on the far side and glittering on the southern, about one hundred meters down. “I got myself into it this time,” he thought. From here one could practically reach out and touch the region in which the Setaur was at large. He glanced rapidly to the left and to the right. He was alone; the ridge lay high above him, a broiling steepness against the black sky. Before, he had been able to look down into the narrow places between the rocks almost with a bird’s-eye view, but now that crisscross maze of fissures was blocked out for him by the nearest masses of stone. “Not good,” he thought. “Better go back.” But for some reason he knew that he wasn’t going back.

However, he couldn’t just stand there. A few dozen steps lower was a solitary block of magma, evidently the end of that long tongue which once had poured red-hot off the great crags at the foot of Toricelli—and which had meandered its way finally to this sinkhole. It was the best cover available. He reached it in a single leap, though he found particularly unpleasant this prolonged lunar floating, this slow-motion flight as in a dream; he could never really get used to it. Crouched behind the angular rock, he peered out over it and saw the Setaur, which came from behind two jagged spires, went around a third, brushing it with a metal shoulder, and halted. Pirx was looking at it from the side, so it was lit up only partially; the right arm glistened, dully like a well-greased machine part, but the rest of its frame lay in shadow.

Pirx had just raised the laser to his eye when the other, as if in a sudden premonition, vanished. Could it be standing there still, having only stepped back into the shadow? Should he shoot into that shadow, then? He had a bead on it now, but didn’t touch the trigger. He relaxed his muscles; the barrel fell. He waited. No sign of the Setaur. The rubble spread out directly below him in a truly infernal labyrinth. One could play hide-and-seek in there for hours—the glassy lava had split into geometrical yet eerie shapes.

“Where is he?” Pirx thought. “If it were only possible to hear something, but this damned airless place, it’s like being in a nightmare… I could go down there and hunt him. No, I’m not about to do that, he’s the mad one, after all… But one can at least consider everything—the outcrop extends no more than twelve meters, which would take about two jumps on Earth; I would be in the shadow beneath it, invisible, and could move along the length of it, with my back protected by the rock at all times, and sooner or later he’d walk out straight into my sights.”

Nothing changed in the labyrinth of stone. On Earth by this time, the sun would have shifted quite a bit, but here the long lunar day held sway, the sun seemed to keep hanging in the very same place, extinguishing the nearest stars, so that it was surrounded by a black void shot through with a kind of orange, radial haze… He leaned out halfway from behind his boulder. Nothing. This was beginning to annoy him. Why weren’t the others showing up? It was inconceivable that radio contact hadn’t been established by now. But perhaps they were planning to drive it out of that rabble… He glanced at the watch beneath the thick glass on his wrist and was amazed: since his last conversation with McCork barely thirteen minutes had elapsed.

He was preparing to abandon his position when two things happened at once, both equally unexpected. Through the stone arch between the two magma embankments that closed off the basin to the east, he saw transporters moving, one after the other. They were still far away, possibly more than a kilometer, and going at full speed, trailing long, seemingly rigid plumes of swirling dust. At the same time two large hands, human-looking except that they were wearing metal gloves, appeared at the very edge of the precipice, and following them came—so quickly he hadn’t time to back away—the Setaur. No more than ten meters separated them. Pirx saw the massive bulge of the torso that served as a head, set between powerful shoulders, and in which glittered the lenses of the optic apertures, motionless, like two dark, widely spaced eyes, along with that middle, that third and terrible eye, lidded at the moment, of the laser gun. He himself, to be sure, held a laser in his hand, but the machine’s reflexes were incomparably faster than his own. He didn’t even try leveling his weapon. He simply stood stock-still in the full sun, his legs bent, exactly as he had been caught, jumping up from the ground, by the sudden appearance of him, and they looked at each other: the statue of the man and the statue of the machine, both sheathed in metal. Then a terrible light tore the whole area in front of Pirx; pushed by a blast of heat, he went crashing backward. As he fell he didn’t lose consciousness but—in that fraction of a second—felt only surprise, for he could have sworn it wasn’t the Setaur that had shot him, since up to the very last instant he had seen its laser eye dark and blind.

He landed on his back, for the discharge had passed him—but clearly it had been aimed at him, because the horrible flash was repeated in an instant and chipped off part of the stone spire that had been protecting him before; it sprayed drops of molten mineral, which in flight changed into a dazzling spider web. But now he was saved by the fact that they were aiming at the height of his head while he was lying down.

It was the first machine; they were firing the laser from it. He rolled over on his side and saw then the back of the Setaur, who, motionless, as if cast in bronze, gave two bursts of lilac sun. Even at that distance one could see the foremost transporter’s entire tread overturn, along with the rollers and guiding wheel; such a cloud of dust and burning gases rose up there that the second transporter, blinded, could not shoot. The giant slowly, unhurriedly, looked at the prone man, who was still clutching his weapon, then turned and bent its legs slightly, ready to jump back where it had come from, but Pirx, awkwardly, sideways, fired at it—he intended only to cut the legs from under it, but his elbow wavered as he pulled the trigger, and a knife of flame cleaved the giant from top to bottom, so that it was only a mass of glowing scrap that tumbled down into the field of rubble.

The crew of the demolished transporter escaped unhurt, without even bums, and Pirx found out—much later, it’s true—that they had in fact been firing at him, for the Setaur, dark against the dark cliffs, went completely unnoticed. The inexperienced gunner had even failed to notice that the figure in his sights showed the light color of an aluminum suit. Pirx was pretty certain that he would not have survived the next shot. The Setaur had saved him—but had it realized this? Many times he went over those few final seconds in his mind, and each time his conviction grew stronger that from where the Setaur had been standing, it could tell who was the real target of the long-range fire. Did this mean that it had wished to save him? No one could provide an answer. The intellectronicians chalked the whole thing up to “coincidence”—but none of them was able to support that opinion with any proof. Nothing like this had ever happened before, and the professional literature made no mention of such incidents.

Everyone felt that Pirx had done what he had to do—but he wasn’t satisfied. For many long years afterward there remained etched in his memory that brief scene in which he had brushed with death and come out in one piece, never to learn the entire truth—and bitter was the knowledge that it was in an underhanded way, with a stab in the back, that he had killed his deliverer.