Front matter (continued 2)

The height was relatively simple. A radar screen, reduced to a vertical slot for economy of space and weight, told him the distance to whatever was below. A Doppler-effect velocity indicator would read off the change in frequency of a crystal-controlled radio signal which his speed produced. This substantially resembled the way an automobile horn changes pitch when two cars pass each other; the pitch drops swiftly at the moment of passing. But there was an observation which was simpler and more direct.

He spotted a bright star near the horizon ahead. He read off its angular distance from the world's edge. Looking aft, under the belly of the ship, he read another angle from the world's edge to another star. Minutes later, he repeated the observations. The star ahead was higher, the one behind was lower. If one star rose faster than the other sank, he would be gaining height. If one sank faster than the other rose, he would be falling. If one rose exactly as fast as the other dropped, he would be in a perfect circular orbit, neither rising nor falling. That was too good to be expected. But from even two sets of observations he could tell the line the ship was following, and hence its speed.

The ship did not have quite the speed necessary for a complete orbit. It needed more. He could guess how much.

He said curtly to Furness:

"We've got to have a two-second push, anyhow. Maybe more later. Get set."

Furness did not reply, but McCauley heard him reporting.

There was singularly little exultation in the small cabin. Furness' face was drawn and colorless behind his helmet plate. McCauley was busy.

Presently, after a warning gesture, he set the rocket timer and pressed the firing button. All the ghastly impact of high acceleration repeated itself. But, lasting only two seconds, it was not much worse than—say—falling from a second-story window down on a hard mattress. It lasted longer, but there was not much other difference. It did not build up to the torture of continued rocket thrust.

Then the ship floated on. There was utter silence. The vertical-slot altimeter indicated a height which seemed absolutely steady. The Doppler-effect velocity meter gave a reasonably satisfactory if not too precise message. McCauley was working intensively on his course when Furness said, with an effort:

"Ground says satellite-watching stations picking up our signal report a good course. It could be a little more to the south."

McCauley flipped on his own microphone-to-ground switch.

"I figure I'm still a little short on velocity," he said crisply. "I'll have to blast again for about a second. Figure me an angle of heading for ten minutes from now, for a one-second blast. I'll report my figures for checking."

He did not bother with the ship controls now, of course. The ship was in orbit, like the numerous satellites circling Earth west to east and north and south. It did not matter which way it pointed. There was no air to impede its progress. As a matter of fact, a trace of rotating motion had been produced by a slight off-centering of the rocket thrust. The ship's center of mass had changed slightly because of fuel consumption.

There was silence. McCauley worked on busily. From time to time Furness spoke as if with great effort. He relayed the altitude from the slot radar. He relayed the velocity from the Doppler gauge. He relayed hull temperature, cosmic frequency, ultraviolet intensity. He did not report any physical sensations, but once he spoke as if in answer to a question:

"It must be out of order if it says that."

He might be referring to the telemetering apparatus which relayed the pulse and respiration and blood pressure readings of the two men in the ship.

In eight minutes McCauley reported the bearing he considered the ship should point to so that a one-second rocket thrust, adding its effect to all previous courses and speeds—plus a correction for the diminished weight of fuel in the tanks—would produce an exactly perfect orbit for the ship. Furness repeated it while McCauley took more horizon-to-star observations to check the present line of motion.

"Ground checks your figures," said Furness. "They say congratulations on perfect astrogation under service conditions. It's right."

"Okay," McCauley said absently.

He went on with his work. The ship was two hundred eighty miles—plus or minus half a mile—above the surface of the earth. An orbit required a speed and rate of downward curvature just fixed so the ship would go downward as the surface curved down, like a glider coasting down a curving hillside and always being the same distance from solidity. Since the earth was a globe, one could coast forever and be always falling, without ever touching the circled world. That is an orbit.

McCauley set the rocket timer and said:

"Here we go."

The rockets blasted. The ship flung itself forward. Again there was the sensation of falling an uncomfortable distance onto a hard mattress. But a one-second blast was a thousand times more endurable than a one-minute one.

The ship had now been aloft for something like thirty minutes, of which ten was airborne flight and twenty free fall in orbit, plus two corrections of course and speed. McCauley had had no time to gaze down at the vastness below him. He knew it only as a huge expanse of mottled tawny-green or blue with many white specks upon it. The specks, which were clouds, were closer together toward the horizon, and at any given moment the rim of the world was a ring of plain white.

Now he checked his work once more and then took time to look at Earth below him. At its speed, the ship should complete one revolution of the Earth in ninety minutes, more or less. Its speed was seventeen thousand two hundred and sixty miles per hour relative to the ground. In twenty minutes of free-fall flight it had covered something over five thousand and seven hundred miles, relative to the ground, and crossed eighty degrees of longitude. The local time down below was something more than five hours later than the local time at Quartermain Base. Sunset would be approaching here, as the earth's shadow moved from east to west like the dawn.

To the right of the floating ship there was only tawny-blue ocean that seemed much darker than ordinary because McCauley was looking down into its depths instead of at a sky reflection from its surface. Behind the ship there was a clumping of the white specks. These cloud masses would be above and around the Cape Verde Islands, now tens of scores of miles to the rear. Below and to the left there was an amorphousness, an indefiniteness peeping up from beneath the cloud cover. That would be Africa. McCauley could see for enormous distances over the cloud-hidden land. He knew that he floated over Senegal and British Guinea and French Guinea and Liberia and the Ivory Coast, all in a matter of tens of seconds. But he could see only at intervals between tufts of white-cottony vapor. Ahead, too, the dark-colored sea swept in, right to left, and in half minutes or less there was no land at all except behind him. Away ahead there was more of Africa, to be sure, because the X-21 sped along a line which would mark the limits of the Gulf of Guinea. The ship would cross the tip of Africa and head down past it to Antarctica.

But McCauley would not see Africa again. The whiteness which was the horizon turned dim where the ship's bow aimed, and the dimness spread to the left. The edge of the round world turned black. It was Earth's crawling shadow creating night. Darkness sped toward the ship, still high above the last slightest trace of atmosphere and glittering intolerably in the unshielded glare of the sun.

"It looks like we're all set, Furness," McCauley said with satisfaction. "We can relax, now, for all of twenty minutes."

Furness did not answer. There was no sensation of weight, of course. Nothing weighed anything. Nothing could be considered light or heavy. The difference between a copper penny and the ship itself was purely imaginary. They had different masses, but both would weigh the same—zero. McCauley suddenly turned off the silent air-circulator in the cabin. He struck a match. The flame flared, but not as a rising leaf shape. It was a perfect ball of incandescence. But it did not continue to burn. It went out, and there was a ball of white smokiness where the flame had been.

"I've heard that'd happen. I wanted to try it," McCauley said amusedly.

A match requires oxygen in which to burn. On the ground, the chemically fostered first flame of the match-head heats the air, which rises and is replaced, whereby fresh oxygen reaches the place of combustion and supports it. But in the X-21, in free fall, hot air was no lighter than cold. It did not rise. The match exhausted the oxygen around it and went out. McCauley turned the air-circulator on again lest he and Furness be similarly surrounded by vitiated air.

"Queer, eh?" said McCauley. Then he looked at Furness. Furness' eyes seemed filled with suffering. His pallor was deathlike.

"What's the matter?" McCauley asked.

Purely by instinct he raced his eyes across the instruments. They said nothing they should not.

"Furness!" snapped McCauley. "What's the matter? What's happened to you?"

With an air of terrible effort—though nothing weighed as much as a hair—Furness moved his left hand away from his side. It came away filled with blood. There was an ominous dark-red patch on the flight suit, and something seemed to be welling slowly out of a puncture in the cloth. The hole was the size of a bullet hole.

"Just before ... take-off," said Furness thinly, "the rocket fuel that was ... bled through the fuel pipes ... went off when you tested ... the engine. It exploded. It threw pebbles like bullets. One ... ripped the general's hat. One ... hit me."

McCauley swore. He felt a sort of bitter anger. Of all the places where instant medical attention for an injured man was impossible, the worst was the close, air-tight cabin of a ship out of atmosphere, traveling at some thousands of miles per hour and heading into night. Descending was out of the question. It was impossible to turn back.

"Let's look at that," said McCauley harshly. "Maybe we can check the bleeding somehow.—Why didn't you report you were hurt? Didn't you know you were risking your life?"

"I suppose," said Furness weakly, but with irony, "that you aren't risking yours!"

Then he winced a little as McCauley's finger explored the hole in the tough cloth. When the rocket fuel exploded on the surface of the ground, the impact of a pebble would have the effect of a bullet. It would numb more than it hurt. Furness knew he'd been hit, of course, but the ship was ready to take off, and the wound might only be trivial. To delay take-off for examination of what might be entirely insignificant would earn him McCauley's contempt—or so Furness had believed. And Furness was in no state of mind to risk that. Nothing short of absolute inability to hide his injury would have made him admit that he'd been hurt or even hit. So he'd climbed in the ship, and done his work steadily until this instant, all the time covering the wound with his hand lest McCauley discover it.

There was no room in the cabin for much movement. McCauley tried to enlarge the hole, but the cloth was reinforced with wire and could not be torn. Furthermore, he had nothing to work with if he could get at the wound—nothing for bandages, nothing to check the bleeding, nothing.... He swore deeply.

Then he felt for a familiar iron ring and pulled it. A tiny pilot chute leaped from his chute-pack. It was designed to pull out his main chute if he had to jump. He tore at it with his fingers.

"We'll pack it anyhow," he mumbled as he ripped strips from the small expanse of nylon. "At least check the bleeding."

He rolled up a strip of white cloth. He was irritated by the insistent feeling that he needed antiseptics he didn't have. He worked at the recalcitrant opening in the cloth of the flight suit and packed the wound with nylon. Then he worked more nylon about and over the packing to make a firm pad. He tore long strips to put around Furness' body to hold the packing fast and tied them tightly.

It was awkward to work where there was no weight. It seemed unreal to attempt the preposterous where there was no sound. He worked swiftly. Suddenly there was a redness in the light reflected all about the cabin from the sunshine that came in the ports.

He jerked up his head, thinking foolishly of fire. Then he saw the sun. It lay beyond a vast curved barrier that shut off all the light of all the stars. The sun was in the act of descending, to be eclipsed by the edge of Earth, and its light came through hundreds of miles of thick air which turned it from a burning golden glare to flame-red, and then crimson, and then ruby-red as he stared. Then its rim was blanked out and it slid swiftly down to extinction. The light went from gold to carmine to ruby and the sun was blotted out in less than ten seconds.

Then the ship traveled through purest night. The cosmos outside its ports was sharply divided. There was a hemisphere filled with the coruscations of a million million stars. The other half of the universe was the night side of Earth, but it looked like the abyss of nothingness from which all things came, and to which it may be that all things will return.

McCauley reached over and switched on lights. Furness looked at him through eyes that seemed deep-sunk in his head.

"You tore your pilot chute," he said thinly. "You've no chance to jump, now."

McCauley scowled. There were various methods by which the ship could be landed or at least its occupants might escape its crash. There was the skip process, in which the ship could be settled down into atmosphere just thick enough to slow it as it bounced out to space again for another settling, another slowing, another bounce. It was considered the most practical way for a ship to get back to Earth after an orbital flight. To choose the final landing place, of course, was out of the question. Also it was believed that even with the best of luck the ship's crew might have to take to their chutes and let the ship crash. But Furness could not make a chute-drop. Nor could McCauley, now.

"Time for a report," said McCauley.

He'd meant to make it, but Furness summoned all his strength. He ran his eyes along the instruments.

"X-21 reporting," he said as loudly as he could. "Just passed darkness line. Altitude...."

He went through the list of readings to be given by voice. They might be picked up by satellite-tracking stations which did not quite pick up the ship itself. They would almost certainly be picked up by South African radio amateurs listening for them.

"More comfortable?" McCauley asked gruffly.

Furness moved his head in a fashion that might be considered a nod. After a long time he said:

"Is there any ... water in the ... survival kit?"

McCauley fumbled. There was. The survival kits were the small parcels which might conceivably mean the difference between dying and not dying if a man had to ditch his disabled plane or jump from a burning one. Together with an inflatable boat, they were included in the X-21's equipment as a sort of pious wish. It was not to be believed that this ship would end its career like a mere atmosphere plane. If the steam-jets didn't work, the most perfect operation of the rocket engine would never get the ship down into the atmosphere, even for destruction. If it got down to the atmosphere there were still several thousand things that could go wrong. It was definitely not likely that its crew could jump to safety in case of need, or land so serenely on water that a rubber raft would do them any good. But the survival kits were there.

McCauley gave Furness water. He did not comment on the complications Furness' injury added to a landing problem that was already complicated enough. Instead, he looked at the clock.

"We're close to Antarctica now," he observed. "We ought to run into moonlight, too."

He peered out of a port. The tiny lighted cabin swam in emptiness, without sound, without sight of anything but remote and indifferent stars. It floated above the part of the world where the Indian and Atlantic Oceans flow together, and where there is unbroken sea all around the antarctic continent. A wind can blow completely around the world there, and rather frequently it does; and the gigantic waves that are engendered are spoken of with aversion by seamen. But McCauley could not see any waves. There was floating ice below, but as he thought of it it changed to the massive ice sheet of the bottom of the world. So the tiny lighted cabin raced over mountains and plains all buried in snow which had been there since the beginning.

He turned from the sight of a universe divided into stars and blackness. There was no practical measure to be taken—not now, anyhow. McCauley might contrive a way to get himself safely down to earth, letting Furness take his own chance with no strength to help himself. It seemed improbable in the extreme that Furness could survive a crash landing, even if no explosion followed. There was very little hope that the X-21 could be landed save in a crash. But it did not occur to McCauley that he was relieved of responsibility. A normal landing was not really hoped for. If McCauley piloted the X-21 into orbit and out again, he'd have done the unprecedented and the next try might go better. But he could not imagine himself leaving Furness in a ship headed for a landing that was bound to be a pile-up....

He couldn't expect to land intact himself, with his pilot chute ripped out and torn apart.

"I'm sorry you tore up your pilot chute," said Furness. "It about kills your chance of getting down to the ground in one piece. And it's my fault. You tore it up for me. But when I came on the ship I didn't think I was hurt badly."

"I'd have done just what you did," said McCauley. "It would have taken two broken legs to keep me from walking over as if nothing had happened to me." Then he remembered. "Report?"

Furness gathered his strength and spoke in an almost natural voice:

"X-21 reporting. We are over Antarctica at the farthest south part of our orbit. Altitude...."

He went through the list, and then his eyes went to the canteen from which McCauley had given him water. McCauley gave him another drink.

"That son of mine," said Furness abruptly. "He reveres you. When I was picked to ride observer with you, he almost went out of his head with pride. I was—I suspect I was a little bit jealous of you. A man likes his son to think he's the greatest man on earth. My boy almost believed it when I was picked for this job. But if I'd backed out...."

McCauley nodded.

"Under the circumstances," he agreed, "you'd walk to the ship and come aboard if you had to carry your head in your hand. A man wouldn't disappoint his son."

"He'd have been so proud," said Furness, "if we'd made it! And I've messed it all up!"

"I'm hanged if I'll compliment you," McCauley said, "but it would have been disgraceful if you'd done anything else. A man has to set an example for his son. And we may make out. In any case we're just thirty-two minutes from some very tricky stuff. I think we'd better think of cheerier things."

"Sorry," said Furness. He turned his eyes away. He brooded.

Seconds ticked by in the cabin. Frost began to form on the ports. There was no air outside, so there could not be said to be any temperature. But the ship radiated heat into empty space and received next to none in return. If allowed to cool until thermal equilibrium with its surroundings was reached, the X-21 would go down to some two hundred and fifty-four degrees below zero centigrade. But that would be in darkness. In sunlight it would be a different matter, and the ship'd be out of darkness in minutes.

They were very long minutes. The altitude radar said that the ship was maintaining the most nearly perfect circular orbit any man-made object had achieved to date. The X-21 was a lonely mote with yellow light glowing from its cabin openings. From time to time, invisibly, radio waves spread out from a stiff metal rod pointed sternward, and some of them might—with luck—be picked up by somebody. But the ship received nothing, here.

It passed south of Kerguelen Island in the blackness, and it was midnight local time, though the ship was only forty-five minutes of free-fall flight from Quartermain Base. Presently the X-21 headed northward and crossed the meridian where it was one A.M. something less than five minutes later. It reached a point south of Australia in under ten minutes more. It swept above the lowermost part of Australia and Tasmania together when the clocks on the ground said five A.M.

It was only when the remotest rim of the blackness which was Earth turned bright—when the dawn could be seen at the farthest horizon—that McCauley thought to look for the moon. It shone down coldly, but it was not bright enough to show him any pattern in the blackness nearly three hundred miles below the ship.

In eight minutes more, however, the sun had rolled up over the edge of the world and below the ship there was ocean. Away off to the left McCauley could see spiral arms of cloud, signifying a cyclonic disturbance moving north across the Coral Sea. Sturdy steamships fought for their lives in that typhoon, and many human beings would die in it. The ship sped on, and there came into the headphones of both McCauley and Furness a beamed message from the naval installation at Guam, which dimly and fugitively could be sighted under an aggregation of white clouds more dense than ordinary. The message said:

"Good work, guys! We're pulling for you!"

Then the Samoan Islands were far behind and dropping even farther. And time passed, and McCauley thought intensively and very grimly, and once again Furness asked for water. There was a clumping of cloud masses underneath and to the east which was Phoenix Island, and almost immediately afterward Washington Island and then Palmyra; after that it seemed barely seconds when a most respectable massing of clouds to the left was Hawaii.

McCauley could see solid ground there, and he talked curtly and very urgently into his own throat-mike, flipped into circuit with the voice transmitter for the occasion. It was not altogether likely that his message, relayed, would arrive ahead of the ship, but it was his only chance to do anything practical in the way of warnings to the ground.

He set to work. He did computations from instrument readings he barely remembered. He included a prayerful hope that the fuel-gauge instruments had been calibrated through their entire range. There was so much ramjet fuel, which might or might not do what it was supposed to do. There was so much rocket fuel, which must be expended to the last smallest drop before the ship could risk touching ground. And there was distance to be calculated, in terms of minutes and seconds instead of miles.

The clock flashed a red light and made a buzzing sound. It was a reminder that now, according to the figure evolved on the ground before take-off, McCauley might begin the attempt at skip landing, the improbable but still least implausible procedure for getting the ship on to the ground in not more than two or three pieces. It should begin with a rocket-driven dive into the atmosphere. He was expected to have enough fuel for that. With downward velocity established, he should bleed out all the remaining nitric acid to emptiness. After it had been completely expelled, and not before, he should wait the number of seconds which would be equivalent to five hundred miles, and then jettison the hydrazine. By that time the ship should hit the outermost fringes of air. He should dive into it until the ship's skin temperature began to rise—a matter of fractions of seconds—and then let the ship bounce out again. It would have lost some velocity and would no longer be capable of remaining in an orbit. So it would come down into the air again, after an interval in which it would cool off, and again it would bounce out like a stone skipping across the surface of a pond until it has lost enough speed to settle quietly to the bottom.

If McCauley attempted such a landing system, his place of entry into the air for a dead-stick landing would not be less than one thousand miles from the point of the first bounce, and it might be three thousand. It could not be calculated. Fractions of seconds and seconds of arc would apply, so McCauley might start his skip-stop descent out above the Pacific Ocean, and the X-21 might finally ditch in the Atlantic somewhere off Newfoundland.

Furness tried to speak.

"Report," he said faintly. "I should report."

McCauley threw the switch for him. Furness summoned what seemed to be his last reserve of strength.

"X-21 reporting," he said almost naturally. "We are well past Hawaii and approaching the continent. Altitude...."

He was halfway through when green solid ground with very few clouds lay directly below, and the Rocky Mountains were a little way ahead. He could not quite detect their height, but the pattern of the soil was distinctive. McCauley flipped on his own throat-mike and said:

"I interrupt. Here is the situation. My fuel tanks read...." He snapped off the readings. "I'm going to swing the ship end for end and burn my remaining rocket fuel to kill velocity. Then I'll adopt such skip-stop practices as the situation requires. I doubt it will require them. We were lucky enough to get a nearly circular orbit. In consequence our velocity is lower than if we'd had to make an eccentric one. We saved fuel unexpectedly in getting into space, and I'm going to use it getting out. Over."

He cut off and made his preparations. His figuring was extremely close. But there had necessarily been a slight margin of fuel. A circular orbit does not require nearly the fuel expenditure that an elliptical one does. But McCauley had made the most efficient possible use of fuel at the beginning. He'd used one long blast, a two-second blast, and a one-second rocket thrust to get into nearly a perfect space trail. He meant to collect for that partly accidental expertness. But he meant to collect much more for an observation.

The observation was that a one-second blast was not a thousandth the ordeal that a sixty-second blast was. No man could survive a long-continued twenty-gravity acceleration. But most men could take a one-second push—and not only once, but many times. With time for recovery in between, and a rocket engine that fired infallibly when it was turned on....

He set the rocket timer.

"This," he said over his shoulder, "may be our last chance to exchange compliments, Furness. But I think you're the same kind of idiot as I am. I'd have come on this trip with my insides hanging out rather than stay behind. So would you. Very nearly, you did. It's nice to have known you. I hope we survive."

Steam-jets spouted at the ends of the X-21's rear fins. In emptiness, the ship spun halfway about until the swiftly moving solidity below ceased to move toward the pointed nose. It fled away. The ship traveled backward where there was no air.

"And here we go," said McCauley.

The rocket timer was set. He pressed the blast button. A second later he came out of near-unconsciousness and set it again. There was another rocket blast. He almost recovered from the effect of it before he set the timer for a third.

Doggedly he set the timer and pressed the button, and allowed himself three full breaths and set it and pressed again. The shocks seemed to become more and more violent and intolerable. They were. With loss of mass, the acceleration of the lightened ship went up to twenty-two gees. He cut the blasts to three-quarters of a second. A rocket cannot be throttled down. It fires full blast or it has no appreciable effect at all.

Quartermain Base was built on a flat, flat plain that extended miles in every direction. Its buildings, from a reasonable distance, were only toy structures, tiny angular objects in the middle of vastness. Overhead there was a sky of absolute blue. It was empty. Below, there was flatness to the horizon. It contained nothing. There was no motion of any sort anywhere. The base lay still and silent under the baking two-o'clock sun. Nothing happened. Nothing....

No. Something was happening. Specks moved out of the miniature buildings. Dots rolled out of the infinitesimal garages. The dots and the specks seemed to mill about uncertainly and then to come to a restless, not-quite stillness. It seemed that something was expected to happen. But there was nothing that could. There was only a great emptiness and a great stillness....

But then there came a faint roaring. It was very faint indeed. It strengthened, and diminished, and strengthened again.

Then a mote appeared in the sky. It came down and down and down, bellowing. The bellowing was the unmistakable sound of ramjets. And the thinnest of high-pitched sounds arose from the specks which were men outside the buildings at the base. The sounds were howls of triumph, shrieks of rejoicing, of gladness that the impossible had been accomplished.

The X-21 came wabbling down out of the sky and leveled off a bare hundred feet above the pebbly plain. It lowered, and lowered, and suddenly yellow dust spouted furiously where its wheels had touched. The roaring cut off. The ship rolled and rolled. Later, it would develop that less than one quart of ramjet fuel remained to be burned before it hit ground.

Shouting, swarming men rushed toward it. Dots which were trucks and cars raced to greet it.

Presently McCauley saluted very formally, standing before a general whose cap was badly ripped on one side.

"Sir," he said, "it looks like we did it. And I'd like to say, sir, that I am very proud to have had Major Furness with me. He's hurt, sir, as I radioed to Hawaii. The ambulance is rushing him to hospital. But he stuck to his job throughout, sir, and I'll be obliged if you'll tell his son that he should be very proud of his father."

3

(Time passed after Ed McCauley became Major Ed McCauley, and most people forgot him. If his name was mentioned, someone might say vaguely: "McCauley ... McCauley? It seems to me I've heard the name." This was because remarkable events don't stay remarkable as time goes past. There was a two-hundred-pound satellite circling the moon these days, industriously sending back not only pictures of the moon's far side, but pictures of cloud masses on Earth which told much more about Earth's weather than had been known before. A drone missile had gone out to Mars, and its instruments suggested that men had better not come out just yet, and other drones had gone past Venus and said definitely that men better not come out just yet. So something had to be done to make those journeys possible. Men had to work in space, testing this and trying that, staying days or weeks at a time when solar flare-particles were not too much in evidence. This meant that there had to be a place for them to live and work. There were plenty of men who'd done spectacular things lately, but this needed somebody who would be worrying not about fame, but about getting a job done right. So Major McCauley received certain orders.)

On as much of the Space Platform as existed so far, a working day lasted an hour and forty minutes. There wasn't much of the Platform, as yet. The greatest bulk was a squat, clumsy metal object which had come up from Earth, pouring out rocket flames, to be the Platform's nucleus. From it now sprouted spidery, flimsy metal girders which reached out in apparent aimlessness. They formed an incomplete skeleton of joined triangles whose final form seemed indefinite. But in time they would form a most unlikely icosahedron traced in threads of silvery metal in emptiness. Although the Platform was barely begun, it grew noticeably as time went by, even though the working day was so brief.

Some people would have challenged the word "day." There was no true night where the first part of the Platform floated hurriedly in orbit some three thousand miles out from the planet Earth. There was light when the sun shone on it, which was two hours and five minutes out of three hours and seven. Despite Luna, Earth's ancient and untidy moon, there was abysmal darkness when the Platform plunged into Earth's shadow. This was not nightfall. When sunlight ended, cut off by Earth's eight-thousand-mile bulk of stone and metal, the phenomenon was an eclipse. Once in each revolution about the world which was building it, the Platform was eclipsed by Earth. When light returned, it was not sunrise, it was the ending of an eclipse.

McCauley was in charge of the Platform's construction crew, which consisted of himself—a major—and Randy Hall—a captain—and Sammy Breen, a second lieutenant in the Space Service. They lived after a fashion in the cabin of the ship that had brought them and a lot of building material up and out to the orbit the Platform was to follow. When a work period ended, they made their way painfully to that cabin. They made sure that they were inside it before the sun touched the outer limits of Earth's atmosphere and turned orange and deep-red and then disappeared, all within ten seconds. It was necessary, for in Earth's shadow the gossamer-like framework lost heat rapidly. Long before the end of the eclipse, the temperature of the bare metal dropped incredibly. Even with Earth nearby to temper it, it fell to something like two hundred and twenty-odd degrees below zero.

So between work periods there was darkness and unthinkable cold, and half the universe was brilliant stars—sometimes the moon was visible—and the other half looked like a hole in emptiness leading to nowhere. Actually, the seeming abyss was the night side of Earth, and sometimes Randy or young Lieutenant Breen used the telescope and found infinitesimal twinklings on it which could be calculated to be London, or New York, or Paris, or some other metropolis. But the night lights of cities on Earth were not remarkably bright, from three thousand miles out in the planet's shadow. Often, too, there were clouds thick enough to mask any man-made illumination. There was not much to see from the Platform in darkness and at an early stage of its construction.

But after the darkness there came light.

It was not dawn, of course. It began as a reddish-pinkish line which precisely outlined a half circle and formed a visible boundary between absolute blackness and the firmament of stars. The line thickened at its ends and then at its center. Instantly thereafter the sun peered—deep-red—around the edge of the planet Earth. It was a very lively sun. In seconds it reversed the color changes of its disappearance, fading from ruby to gold and then to the furnace-flame color it shows out of the atmosphere. And the crescent of lighted Earth grew broader and broader and suddenly seas and continents and oceans and islands seemed to come pouring out to cover the darkness, like creation happening as a flood.

Then, while the partially built Platform swept onward, without sound or sensation of movement, nothing else happened for a certain time. The three men inside the cabin waited for the metal to warm up from the temperature of liquid air. During full sunshine it went up to the temperature of low-pressure steam. When all the framework was warm enough so it was no longer brittle, the cabin air lock opened. McCauley came out in a silvery space suit. Captain Randy Hall followed him. Lieutenant Sammy Breen came last. McCauley surveyed the framework. Even a tiny meteorite could do damage, because any such object could be expected to hit at a velocity of seven to forty miles per second.

But when his inspection was over, McCauley slung a space rope around a girder, straddled the metal beam, and pulled himself effortlessly along to its first triangular junction with the other frame members. He had no weight. Nothing had any weight. One could not fall from the Platform, but one could very easily become lost from it. McCauley had acquired a certain fanatical concern about precautions against loss of contact with the only object within some three thousand miles which would let a man go on living.

When he reached the first junction of frame members, McCauley unlooped his space rope from behind the junction, looped it again beyond the joining place, and crawled over to straddle the next girder and slide along it with equal absence of effort until he arrived at the place where he'd left off work a little over an hour before. Randy Hall and Sammy Breen, meanwhile, emulated him, going in other directions. Within five minutes of coming out of the air lock they were perched at three separate places on the absurd framework.

With quite inadequate-looking cords they drew large metal beams toward them from their place beside the cabin. McCauley, for example, pulled at a thirty-foot girder with a piece of string. It stirred and shifted and floated to him. He stopped it, his knees holding him fast. Then—very clumsily because of its mass—he maneuvered it into place, slipped bolts through the ready-drilled holes, and tightened up the nuts. He finished his first girder. Randy completed his. Sammy Breen got his section in place, and then stopped.

"Major, sir," said his voice via space phone in McCauley's helmet phones, "there's something wrong here. A bolt doesn't go all the way through its hole. It won't force. The hole needs to be reamed out."

It was a trivial but annoying happening. The parts for the Space Platform had been cut out, shaped, and drilled on Earth. In theory they should fit perfectly together in space. But somebody had scamped on an inspection job and the result of his carelessness had to be repaired. It had to be done in a nondescript, crazy framework that was hurtling along in orbit at something over eleven thousand five hundred miles an hour. It shouldn't have happened.

"Memorize the part number for report," said McCauley, "and get the reamer and clear it."

"Yes, sir," said Breen.

McCauley pulled gently at a cord and a second girder stirred and floated gently toward him.

Below, the sunlit surface of Earth had an extraordinary appearance. It was some sixty-five degrees in diameter. At its edges the shapes of land and water—the planetary markings—were foreshortened and crowded together in an unparalleled fashion. A twelve-inch globe looked at from five inches away will give something of the same effect. From one side of the disk the markings moved toward the center, thickening and taking recognizable form as they neared the middle. Then they went on, distorted in a different fashion as they approached the opposite edge. When McCauley set his second beam in place a wildly twisted Isthmus of Panama appeared out of the misty whiteness which bordered Earth from where he floated. In half an hour it would be directly underneath and plainly recognizable. In another half hour it would be a new shape entirely. Then it would vanish. Only the center of the visible disk resembled any map-maker's representation, and that spot changed and changed and changed as the Space Platform hurtled past. At any given moment McCauley could see a ninth of all the planet's surface, but only a fraction of what he saw was familiar, and that changed continuously.

Sammy Breen slid along the Platform's frame to the cabin, the ship which had risen to this place from Earth, but would never return to Earth again. Arrived at the cabin, he seized a handrail, loosened his space rope, and pulled himself to the air lock. Immediately, of course, air would flow into the lock and he could emerge into the cabin's interior. He'd get the tool he needed for a job that should have been done on Earth. Then he'd come out again.

Randy tapped on the girder he'd just bolted into place. The vibrations passed through the metal and through McCauley's space suit to the air within it.

"I just happened to think," said Randy cheerfully, "that people down on Earth are all excited about this thing we're building. They think it's wonderful. And so it is, at the present moment. But I'm thinking that in a little while it won't be wonderful. It'll be old stuff. And the day'll come when it's a nuisance. There'll be complaints that it's in the way, barging around through space. It'll be in the way of ships taking tourists on week-end trips to Mars. They'll say it's a danger to astrogation. They'll say it should be cleared out of space. They'll insist that it be junked."

McCauley grunted. Randy was probably right. But just now McCauley held himself to a three-by-five-inch hollow metal beam, with a million million stars shining in all possible colors at the same time as the sun. He continued to work on, building the Platform that some day would be considered a nuisance. Three thousand miles away, geographical features squirmed and twisted themselves in their progress across the disk of Earth.

"But there'll come a time," said Randy cheerfully, "when one of my twenty-five-times-removed great-grand-sons will be spanked by his mother. He'll howl. It will be a very commonplace sort of happening. The only thing odd about it will be that it won't happen down on old Earth below us. It'll happen off somewhere on a planet that nobody's dreamed of yet, circling a sun that nobody's bothered to name, off yonder somewhere in the Milky Way."

McCauley grunted again.

"You haven't any kids yet, let alone great-great-grand-kids. You're not even married. Why the sentiment?"

Randy's voice came clearly in the helmet phones.

"I've been trying to think of a reason for me to be here," he explained, "playing with an oversized Erector set, instead of chasing some girl down on Earth. And I realized that this Platform, which will eventually be junked, has to be built before we can hope to colonize the nearer planets, let alone the stars. So now I know why I'm here. I'm doing this so my many-times-removed great-grandchildren can get their spankings all over the galaxy instead of only on the insignificant earth below. That's a noble purpose! I feel better."

"Good!" said McCauley, with irony.

He felt metallic clankings through the girder on which he was working. He turned his head within the space helmet. Sammy Breen had come out of the air lock, guiding himself by a handrail to a position astride a beam. He slid swiftly along its length. He came to a junction, flipped his space rope around to the far side of the joining place, swung over, and slid to the next junction like someone coasting down a stair rail. He was a cheerful young man, Sammy Breen.

"Sammy," said McCauley, "hold everything. I'll be over."

When people encounter each other only occasionally, there is no particular need for them to think intensively about each other's feelings. But three people isolated in an enforced intimacy much closer than that of cellmates have to take thought. When one of them is responsible for the other two, tact has to be practiced painstakingly. When one of the three is a young man who doesn't believe that anything can happen to him because nothing ever has, the situation calls for extreme care. McCauley had to use his brains if Randy and Sammy Breen were to be able to work with him under exacting conditions like these.

He unhooked his space rope, rehooked it past a junction, and pulled himself toward the place where Sammy Breen had come to a stop. It was, of course, at a place where two of the frame pieces of the Platform should join a third. They were to be bolted together and then another long section of framework would be added, which in turn would have yet another beam placed and bolted to it so the construction could continue. At the moment, however, a bolt hole needed to be reamed so the parts could be bolted together.

McCauley arrived at the corner of a triangle. When linked to all the others, this triangle would ultimately support the skin and hold the interior partitions of the Platform. Again he slipped his space rope over the junction, hooked it, followed it, and went on toward the place where Sammy Breen was. Sammy's voice came out of his helmet phones.

"I saw a man do this once in a circus," said Sammy. "I thought he was wonderful. But I can do it!"

McCauley looked up. Sammy Breen had his space rope hooked around the girder, to be sure. But now he floated, head toward Earth, with one finger barely touching the metal beam. A photograph would have shown him apparently supporting his whole weight on a single finger. But here there was no weight. Nothing drew Sammy toward either Earth or the Platform. But for his space rope, the lightest thrust of his finger would have sent him floating slowly, implacably, helplessly away from the spidery floating object, to drift alone through space forever.

"I hope you checked your rope before you came outside," McCauley said dryly.

"I did," said Sammy nonchalantly. "It's okay."

He tried to pull himself back to the girder with his fingers. He couldn't quite reach it. He was no more than half an inch from a fingertip hold that would have been more than enough, but he couldn't make it. He reached and reached, and his movements made his body in its space suit revolve ridiculously upside down and otherwise. Then he couldn't get his hand anywhere near the girder.

McCauley watched. He was unreasonably tense. But Sammy rather sheepishly gave a tug on his space rope and floated back to firm contact with the Platform.

"Not to be finicky about it," said McCauley, "that wasn't wise. There was only one chance in ten thousand that anything could happen, but there was no need to take it."

"Yes, sir," said Sammy Breen.

McCauley settled down, three feet from the end of the beam that was to be bolted to the one that needed reaming. Sammy Breen gripped that beam between his thighs and hauled the reamer to his hand. At work on the Platform, in emptiness, a man did not carry things, he towed them on cords. If he let go of any untethered object it might stay where he put it, in mid-space, but it was much more likely to have some small motion relative to his which would make it drift placidly out of reach forever.

Sammy Breen set the reamer in place in the bolt hole and pulled its trigger. It cut metal. But it dragged unreasonably at him, trying to turn him in the direction opposite its own rotation. Tiny chips and metal dust twinkled in the fierce sunshine. They floated away. They would never fall to Earth. Never. The reamer went through and Sammy cut off its power. He tried to pull it out. It stuck.

McCauley watched. He'd made a rule that nobody should do anything in the least out of routine without another man nearby. The three of them did not work together at one spot ordinarily. In the kind of conditions customary here, they'd be hopelessly in each other's way. But he'd issued the order requiring two to be together on any unusual job. Now, having obeyed his own rule that there must be a second man at hand when anything beyond simple bolting was to be done, tact made him keep silent while Sammy did it his own way. Too-close supervision and too-constant instruction can make for inefficiency. Worse, on a job like building the Platform, they can make for friction. McCauley watched without comment. He'd have done this thing differently. But it would be unwise to insist that it be done his way.

Sammy jerked at the reamer, which meant that he also jerked himself at it. He slid along the girder he gripped. McCauley said nothing. He'd criticized Sammy's horse-play a moment earlier. He did not want to make a second criticism now.

Sammy reached out—it would not be true to say that he stood up—and put his foot beside the reamer in the bolt hole. The position gave him leverage. He pulled violently. It was a wholly reasonable, completely natural, thoroughly matter-of-fact action. A man pulling something stuck in a hole braces himself exactly that way to get a strong pull at it. But this was on the Space Platform, where there is no weight.

The reamer gave. It came out abruptly. Sammy Breen shot away from the beam to the full length of his space rope—and the space rope slid off the end of the beam. He was headed for infinity with the reamer in his hand.

McCauley grabbed. He never knew how he managed to make so swift a motion in his clumsy space suit. But he hurled his body forward and snatched at the same instant. He caught the rope. But to reach it he'd had to lose his own leg-grip on the beam. The impetus of Sammy's leap jerked savagely at him. He squeezed his legs together in a frantic effort to hold fast by friction. He tried to turn his toes in to catch hold before he slid completely clear. But the feet of space suits do not pivot laterally so he could not turn them inward. Holding fast to Sammy's space rope, he was jerked inexorably clear and he and Sammy Breen floated away to emptiness together.

It was neither a rapid motion nor a simple one. The jerk had come at an angle rather than straight out. The two of them revolved slowly around each other at the two ends of the rope. McCauley held on grimly, braced for the countervailing tug of his own rope when it tightened.

It did tighten. And then it slid. The spot where Sammy had meant to bolt two girders together was, naturally, the point where the two frame members would complete a new triangle. It was to form one of the triangular facets of the twenty-sided figure the Platform would constitute when completed. But....

McCauley's rope slid, and caught, and slid again. Then it came free. Before it came free it had slowed the two of them, to be sure. It increased the rate of their spin. But it slid off to emptiness and the two of them went away from the Platform, revolving fairly rapidly about each other, held together by Sammy's space rope.

Their speed around each other was greater than the speed at which, as a pair, they were drifting serenely away. At one point in each rotation one of them approached the Platform while the other moved away from it. A second later the other spun toward the Platform and the first one moved toward emptiness. But together they drifted very, very deliberately toward the stars.

McCauley swore. Then he said curtly:

"Lieutenant!" The use of the term instead of the name was wise. Sammy Breen might be a horrified young man. But Lieutenant Breen was something else.

"Sir," said his voice unsteadily in McCauley's headphones, "I'm sorry, sir. I should have...."

"I'm going to throw you my space rope," snapped McCauley. "You will catch it and obey my orders."

"Yes, sir."

"Catch!" snapped McCauley.

He threw the rope. Because they were rotating, the first cast was wild. Sammy Breen wasn't where he threw the rope when it got to him. It had McCauley's own speed of rotation, so it did not go where he aimed. It took half a dozen attempts to get the rope to where the younger man could catch the squirming line in the stiff gauntlet of his space suit.

"Now, fasten your reamer to the rope," commanded McCauley. "Tie on your other tools. Give me every bit of equipment you've got except your air tanks."

"Y-yes, sir," said Sammy's voice in the helmet phones.

Spinning as they were, the universe of stars and sun and the vast, unfamiliar, brilliantly lighted object which was Earth seemed to be engaged in a monstrous saraband. Now Sammy was a glaringly bright object with full, blazing sunshine hitting his space suit. Again he was lighted from the side with the brightness of Earth behind him, racing past his body with all its features blurred. Yet again the stars seemed not points of light but streaks, and there were moments when the sun itself was a flashing band of intolerable brightness. But somehow this vast and silent motion of the cosmos seemed unreal. It was like a hallucination. It was like a nightmare in which absolutely nothing was true; in which there was no actual sun or Earth or stars, because in reality those things did not swing in lunatic sweeps around anybody, anywhere.

While the younger man blindly obeyed McCauley, they continued to drift away toward infinity. Curiously enough, the centrifugal force caused by their spinning gave McCauley the only sensation of weight that he'd had since his arrival at the orbit of the Platform.

Randy's voice came in McCauley's headphones.

"Ed! My God!"

His tone was anguished and hopeless.

"Randy," said McCauley in clipped tones. "You can be useful. When we're in line with you, say 'tip.' Say it again. Keep it up."

Almost instantly Randy said, "Tip." Then, "Tip." Then, "Tip" again. Sammy Breen said hoarsely:

"All my equipment, sir, is fastened to your space rope. Everything but my air tanks."

"Right. Now let go of it," commanded McCauley. "Randy, how fast are we drifting away?"

Randy's voice came hoarse and harsh.

"I don't know. Slowly, but you're a good hundred and fifty feet off. A trifle more."

McCauley calculated aloud, for his own comfort as well as the information of Randy and Sammy Breen.

"We've been drifting maybe half a minute. Those 'tips' of yours were about one second apart. We're spinning once in two seconds at the ends of a thirty-foot rope. Each of us has an angular velocity of something over forty feet per second. Forty-five or better. Our joint speed away from the Platform—a hundred and fifty feet in thirty seconds.... Somewhere around five feet per second. Not much more, anyhow! We're practically crawling away, but we're spinning like blazes."

Randy said, dry-throated:

"Even if we had rope, Ed, I couldn't get it to you."

"I know," said McCauley curtly. "Lieutenant?"

"Yes, sir," said Sammy Breen's voice, quite steady now. "I've thought of something, sir. If we act fast and I cut the rope at just the right instant, sir...."

"Keep quiet!" snapped McCauley. "That's an order! Right now I want you to push that equipment at the end of my rope away from you as hard as you can, in the direction we're spinning. The way we're spinning! You've got too much angular velocity. Understand?"

"Yes, sir," said Sammy. "I'm glad, sir...."

"Keep quiet!" snapped McCauley again. "Push!"

The cumbersome and weighty mass of equipment, which on Earth would have weighed nearly as much as Sammy Breen, swung away from him. It went around until it was behind McCauley. There was now a system of three weights on a string. The middle one, which was McCauley, did not spin around. He only rotated. The others swung in a wide circle about him.

"Get set, Randy," he said sharply, "and have your rope ready."

"What...." Then Randy understood. He swore.

McCauley let go of Sammy Breen's space rope at an instant when in his circle around McCauley he moved toward the Platform. At that instant, of course, McCauley still moved away. But he let go. The result was that he sent Sammy Breen floating back toward the spidery metal framework, and he himself moved away faster. In effect, he'd taken to himself a large part of Sammy's momentum toward destruction. But not quite all. There was still Sammy's equipment, which formed a new two-weight system of masses spinning about a common center of gravity. Yet it did look as if he'd seen the possibility of saving one of the two of them, and had taken the action which gave that chance at life to Lieutenant Sammy Breen.

"Major!" Sammy cried out desperately. "This is all wrong! It was my fault! I should have cut the rope! I protest, sir...."

"Shut up!" rasped McCauley. "Within a minute or two you'll float to the Platform. It's not likely you'll strike a beam direct. Get ready to throw your rope to Captain Hall so he can pull you in!"

Now he cut his own space rope and held its end. With Sammy Breen gone away toward life, he and the mass of equipment at the rope's other end still had a spinning motion. But it was a slow one. Yet he could repeat the same trick he'd worked with Sammy, though not with the same effectiveness. He could sacrifice the weight at the end of his rope, just as before he'd sacrificed himself. If he chose the moment when in their spinning the heavy objects were moving fastest toward the stars, that would be the moment when his own motion toward annihilation was least.

He let go. The awkward clump of tethered space equipment went swiftly toward nowhere. McCauley seemed to cease to drift away from where Sammy Breen, floating steadily, made bubbling noises to himself as if he were sobbing in shame that McCauley had given him life at the expense of his own. McCauley was now a good six hundred feet off in emptiness from the lacework of silvery bars.

"How am I doing, Randy?" asked McCauley curtly. "You want to catch Sammy when he comes through the framework. Get to where you can help him. But when you have time, make an estimate on me."

There was silence. The Platform hurtled on around Earth. The changing, distorted patterns of land and sea seemed to writhe as they went past in the intolerably brilliant sunshine. But over at the very edge of the bright disk a little trace of blackness appeared. That would be the night line on Earth. The Platform and its company moved separately yet together toward that darkness. Presently it would cover half the disk of Earth, and then it would sweep on until only a swiftly thinning crescent of light remained, and then the Platform would plunge into utter darkness, where most of the cosmos was only shining stars and a pallid moon, the rest the blackness of the Pit. And of course, in this darkness the building satellite's unprotected substance would—like McCauley—drop to a temperature of two hundred and twenty-odd degrees below zero.

"Throw your rope to Captain Hall!" McCauley snapped to Sammy Breen. "I know you'll turn somersaults. But throw it!"

Silence again. McCauley made his own estimate. It was not good. He did not drift swiftly away into the emptiness which would presently be blackness and cold and death. But he had not lost all his velocity away from the Platform.

He took the wrench with which he fastened together the frame members of the unlikely object which he left with such deadly deliberation. He drew up his feet below him. He placed the wrench under them. At a carefully chosen instant he thrust it violently away.

He pushed the wrench toward nothingness. Its mass may have been ten pounds on Earth. His own mass, with his space suit and air tanks and the like, was probably thirty times as much. If he thrust the wrench away at thirty feet per second—and he did—he would change his own velocity by one foot per second. This might mean a slowing of his motion away, or it might mean a terribly slow drift back to the Platform and a chance for life.

He took his space knife. It might weigh a pound. He threw it. Systematically and unhurriedly he denuded his belt of the tools hanging to it. A mass of possibly sixty pounds, thrown violently away, changed his velocity by as much as six or—considering that he had less mass with each bit of mass he discarded—probably seven feet per second.

"I've got Sammy," said Randy's voice, hoarse and strained. "He's all right.... You don't seem to be going away any more, Ed. You're no farther than you were. Maybe I can knot ropes.... No. There aren't enough."

"Right," said McCauley with an odd calm. "There wouldn't be time, anyhow. We're heading for eclipse. I've got to get back on my own—and fast. The storybooks say rockets are used by men in space to go bobbing around in their space suits. We know better. But I'm going to use one air tank."

He writhed in the harness outside his space suit. He managed to detach one of his two air tanks. He aimed its pipe carefully.

Air poured out with a rush when he opened the stop-cock. There was two thousand pounds pressure to begin with. The tank had been in unshielded sunshine for more than an hour. The effective pressure of the air had tripled, at least, because of its rise in temperature. It made a rocket jet of gas. McCauley could feel its quick, sharp tug at him.

It went empty.

He put it under his feet and gave it the most violent of thrusts toward the Milky Way. Now he could see that he had given the discarded things all the momentum that had carried him away from the Platform, plus all he had taken from Sammy Breen. He was moving toward the Platform. It no longer dwindled as time went by. It grew in size with an intolerable, incredible slowness. But that slowness amounted to doom.

"You're headed back," said Randy's agonized voice in his helmet phones. "But it's slow, Ed! It's desperately slow!"

The blackness, which was Earth's own shadow cast upon its night-side surface, was now fully halfway from the rim of the world toward that halfway point which was the middle of the space that Earth occupied within the cosmos.

"There's about fifteen minutes left before totality," said McCauley with deliberation. "I've one more thing I can throw away. But I need to steer with it too, and I can't be accurate at this distance. I don't dare to use it from so far away. I've no space rope left to throw for you to catch. I have to throw that last thing away at the very last instant."

He heard confused sounds. Sammy Breen, back at the Platform, made incoherent noises. He probably gesticulated, because Randy understood.

"Yes," said Randy's voice harshly. "Make it quick. But take care! More than your own life depends on your being careful now!"

Sammy Breen gulped. McCauley heard him. Then silence again.

It was necessary to wait. McCauley was a tiny, glistening object in emptiness, a desperately long way from the equally glistening Platform. He turned slowly, foolishly, as he floated. Away off against a background of stars—but the sun moved momentarily nearer its edge—there was a shape that now was not quite half of a circle of brilliant light, and more than half of a circle of darkness like that of the Abyss. It did not look like Earth. It had not the least appearance of a world in which human beings lived and moved and breathed and loved and died. It was a monstrosity whose details changed their shape as half minutes and quarter minutes went by. And continually and implacably the darkness spread over more of it.

Randy's voice came desperately.

"Hurry, Sammy! Give it to me and get back into the cabin. We won't have time to wait our turns at the air lock.... Right! Now get back in the cabin!"

"How am I doing now, Randy?" McCauley asked calmly. "How's my line of motion?"

"I don't like it!" said Randy fiercely. "It's off to one side! Sammy just brought me all the extra space ropes. He tied them together inside. I'm checking them now. There are four of them."

McCauley said:

"I hate to seem overanxious, but how much will I miss the Platform by?"

"Too much," answered Randy bitterly. "What have you got left that you can throw away to steer by?"

"Eighty pounds of mass," said McCauley with composure. "But I have to wait until the last second."

Silence again. Darkness covered three-quarters of the Earth's strange disk. It was not the darkness of a night on Earth, with trees and plants and men as darker shapes against starlit or moonlit ground or sea. It was the blackness of nothingness, of annihilation.

"You can't stay out much longer, Randy," McCauley said. "I'll have to try it."

"There's the moon," said Randy hoarsely. "I can see by that, ... maybe."

Again silence. The shape which was Earth became the thinnest of crescents. The sun blazed fiercely almost at its outer rim.

The sun turned orange, crimson, ruby-red. It ceased to be a circle. One edge blacked out. It was half blacked out. It was gone.

McCauley wriggled in the harness outside his space suit. He spoke deliberately.

"I'm going to take all the deep breaths I can, Randy. I'll even let a little extra pressure into my suit. Then I'll take off my last air tank and try to steady myself with its jet of air. Then I'll put it under my feet and jump against it, toward you. Now listen! If anything goes wrong, it won't be your fault! Understand? Don't take any crazy risks. If I go on past the Platform, get into the cabin fast before the cold comes! That is my order! I expect you to obey it!"

"Cripes, Ed!" Randy's voice broke.

McCauley bled air into his suit. He breathed deeply and fast, saturating his lungs with oxygen. He removed the tank and then spent precious seconds stripping away the harness that had held tools and extra equipment to his suit.

He jetted away the air. In the utter silence that was the universe, the whistle of escaping compression was conducted to his gloved hands and so to the remaining air inside his space suit. He used the jet with infinite care. The tank tugged briefly and his random body rotation stopped. He saw the Platform, almost incredibly dim in the moonlight.

He jumped against the mass of the air tank and harness together. In seconds he could see that he was moving closer toward the silvery, spidery framework in the moonshine. He kept himself still. Nothing he could do now would add anything to his chance for life, and exertion would lessen the time left before he suffocated for lack of air.

He relaxed by an iron effort of will. He had gambled. He could win or he could lose. But he must keep the calmness of a man who sees the stakes down and waits for the outcome.

The Platform was no more than a hundred and fifty yards away. No more than a hundred.

He would miss it. He would pass sixty feet or more beyond its outermost edge. Randy would undoubtedly try to throw him the space ropes he'd tied together. The odds were enormously against his being able to catch them.

He said nothing. If Randy thought that he'd run out of air before he reached the point nearest the Platform, he would reproach himself less; he'd believe he couldn't have done anything, anyhow.

Fifty yards. Twenty. He saw glittering metal only sixty feet away. But there was no conceivable action he could take to move himself that sixty feet.

Then something dark came toward him. It grew larger. It was Randy, plunging out from the girders with a hundred and twenty feet of space rope trailing behind him, made fast to a firmly bolted beam.

He collided with McCauley. McCauley felt him gripping fiercely. He felt Randy clinging to him savagely against the jerk of the rope which must tighten presently.

The jerk came, violent and abrupt.

Randy gasped in relief. He took away one space-suited arm to haul at the space rope that had checked McCauley's slow drift past to nothingness.

"Very nice work, Randy," said McCauley composedly, "but you took an awful chance."

They bumped against the substance of the Platform—one square metal tube some three inches by five.

"Can you hold on?" demanded Randy, panting. "I'll give you one of my air tanks!"

They were out at the farthermost limit of the framework of the Space Platform. McCauley's faceplate began to frost now, with the loss of heat to the darkness.

"Make it fast," said McCauley. "We want to get in out of the cold."

Fumblings. Clatterings. McCauley heard Randy's teeth chatter, which might be cold or might be reaction from the terror he'd felt on McCauley's account.

"Right!" McCauley said suddenly. He felt air blowing past his face. Randy's extra tank was connected. "I'm all set now. Let's get headed for the cabin."

"Hold it!" said Randy angrily. "You tie a space rope to yourself and loop it around a beam! Do you want to take a chance on slipping away? Maybe there is only one chance in ten thousand of getting lost, but there's no need to take that!"

"Okay, boss," said McCauley. "I shoulda known better."

Hardly more than seconds later he was sliding toward the cabin, Randy following close behind. He came to a joint where three of the beams came together. He unlooped his space rope from the near side, looped it around beyond the joint, crawled over, and slid again.

The cold came fast, but they would make it. Already his mind was at work on a matter that bothered him. He was in charge of the building of the Platform. That meant that he had to think about the feelings of the men under him. Randy was all right. He'd done a good job, and he knew it. But Sammy Breen was different. He was a very young officer, and he felt right now that he'd blundered and imperiled a senior officer—practically killed him, in fact—and he'd be in a state of almost hysterical self-abasement. Not a good state for young officers to be in.

When McCauley squirmed out of the air lock, young Sammy Breen looked at him. He was deathly white and utterly ashamed.

"Hm," said McCauley ruefully. "Sammy, I think I'll have to report myself for incompetence. When a second man's standing by while somebody does a tricky job, he ought to be sure that his space rope can't slip. I didn't. I doggone near got you killed, Sammy. I'm sorry."

Sammy Breen made an inarticulate sound. Then Randy came out of the air lock.

"For the love of Heaven, Sammy!" he said, scolding. "It's your trick to fix food! We've got less than an hour for eating before the sun comes back. And you haven't even got the stuff heating up! What kind of a cook are you, anyhow?"

Sammy swallowed. He swallowed again. Neither McCauley nor Randy mentioned the late so nearly complete disaster. Randy was kidding him. McCauley made a joke of it, too.

Sammy put the food on to thaw and heat. He struggled to become worthy of the companionship of men like McCauley and Randy Hall. Presently he swallowed and said accusingly:

"You characters were late for dinner. Don't blame me if it's cold!"

He looked anxiously at them. He hoped....

McCauley grinned at him. Randy laughed. They laughed together. Lieutenant Sammy Breen felt wonderfully good. And he would be very careful hereafter.

4

(There was high adventure on the moon when it was first colonized. Men faced various ways of dying—all of them unpleasant—and found that simply staying alive was a great satisfaction and a full-time occupation. Because of this spirit—which is that of true adventure—there came to be bases where hydroponic gardens freshened the air and men took continued living as a matter of course. This, obviously, was not adventure. So problems arose. Men began to be moved by other motives than the zest they'd known at first. But there were still a great many ways of getting killed on the moon. So there came a time when Colonel Ed McCauley had to insist that certain men under his command put first things first, as adventurers do, and not act for the gratification of their problem personalities.)

Traveling at moon gait, which is the standard travel pace on Earth's big moon, McCauley had ten of the last twenty miles behind him when he saw the sledge trail in the dust. He frowned at it and looked over to the west. He saw Earth, blue-green and glamorous, hanging as usual in the lunar sky just above the edges of the ring mountains. But Earth was always just there. He squinted at the sun through the faceplate of his helmet. It was a trifle over ten degrees above the horizon and it moved across the black, star-speckled sky at half a degree per hour. In twenty hours, then, lunar night would fall. And here was the sledge track that said that the relay unit for Repeater Two, carrying word to and from Farside and the rest of the human race, had passed this way en route to be set up; but the lack of returning footprints said that the men with it had not come back.

Repeater One was already in place and ready to operate. Repeaters Three and Four had also been put in position by men from faraway Farside Base. Repeater Two was necessary to bring Farside Base into communication with the rest of the cosmos. Two weeks of lunar night with no word from outside the base and not even Earth to look at in the sky—this would not be good for the men on Farside.

McCauley stopped. He'd been moving in that swooping, semi-flying fashion which the lesser lunar gravity allows. He stared at the trail. No, the men had not come back. Yet he'd ordered a party of two to set up the relay unit. It was to be put into place on the very tip of a mountain that was now away below the horizon. There it would be in line of sight of Repeater One, which was relatively near, and Repeater Three, which was farther away but which in turn could relay signals to Four, which was farthest away of all. From Four, the relayed messages would go on to Farside Base. When all this was accomplished, the Grimaldi Base ten miles distant could communicate with Farside through Repeaters One, Two, Three, and Four, and with Earth by line-of-sight transmission; so Farside could communicate with Earth and through Earth Relay with all the other moon bases—in short, with all humanity. But Two should have been up and in operation by now.

McCauley shook his head impatiently inside his space helmet. He'd been away from his command for thirty hours, during which he'd traveled twenty miles on foot, at moon gait, to Gerritson Bay. It wasn't a bay, of course, but an intrusion of now-frozen lava into the mountainous country here at the edge of the moon's earthside surface. He'd been met by a moon jeep and had traveled seven hundred miles over a mare—one of the dark areas that were once thought to be seas but actually were dry and level—to the main lunar base near Hipparchus. He'd had a one-hour conference with the base commander there, trying to work out something to prevent the first murder on Earth's big satellite. The conference was unsatisfactory. He'd come back to Gerritson Bay and now he'd covered ten of the twenty remaining miles to Grimaldi Base. When he reached Grimaldi the excessively irritating problem of a murder in the making was still unsolved, and now in addition there was the failure to complete placing the relay at the site of Repeater Two. The sledge ought to be in its place on the peak which was invisible from here, and the men who'd set it up should have returned. They hadn't.

He flipped on his space radio and said curtly:

"McCauley calling relay placing party. Come in!"

There was no answer. He called again and again. Then he called Grimaldi Base. Again no answer. He was out of radio contact with all humanity on the moon—even his own base ten miles away—though by switching frequencies he could raise Earth Relay a quarter million miles farther away. The men with the moon sledge might only be behind a mountain wall or anywhere in any direction below the horizon, but radio communication on the moon is limited to line-of-sight because there is no air and hence no layer of ions to bounce radio signals down behind obstacles or around the moon's curvature.

McCauley started off again, fuming. Moon gait is a highly specialized form of travel. In one-sixth gravity a man can cover ten miles an hour over rough ground if he knows the trick of the gait and the trail is marked. He travels in slow-motion giant steps, with something of the effect of an extremely deliberate ballet. He begins with a leap up and forward, and he rises slowly and deliberately while soaring ahead. At mid-leap he is six feet higher than at take-off. Then he descends slowly and with dignity, touches ground and strides at the same time, and bounds up and ahead once more. There are long seconds between steps and long yards between strides. When a person is used to it, moon gait is almost restful. Some people even find it familiar. They've dreamed of such effortless half flight in their sleep.

Now, though he was disturbed, McCauley made two miles with no other known cause for worry than the lateness of the two men who'd placed the relay and the prospective killing he'd had on his mind before. He passed between precipices and over dust-strewn stone and through winding defiles. The two men should be back....

Then he spotted something. Abruptly he raised his arms and extended both feet before him. He came down to the ground and stopped short. Then—not soaring this time—he walked back to an object on the trail.

It was an air tank, exactly like the two tanks at the back of his own space suit. It had been dropped from the moon sledge. It would hold air for one man for three hours.

Men driving a moon sledge would wear one tank on their space suits for safety, and they'd shed one for lightness. They'd breathe from the much larger tanks on the sledge itself while they traveled. Spare and extra tanks like this would ride on the sledge. It was not easy to imagine that it had dropped. One man would go on ahead of the sledge and one would follow. It was hard to believe that the second man would not notice the loss of an air tank. Air tanks were life. True, a sledge party always had more air than was needed for any expected journey—a good margin for emergency—but this tank could cut the margin for this journey seriously.

McCauley growled to himself. He knew the calculations for placing the relay. The mountain beyond the horizon was an eight-hour journey by sledge—the horizon on the moon is only two miles away instead of eight. Breathing from the sledge, the men would arrive with one tank on their suits untapped, another, also untapped, to be mounted; and an extra tank for good measure. When they'd put the sledge in place and aired its beams and set up the nondirectional auxiliary antennae, they'd start back with two full tanks each and another one for reserve. They'd make better time coming back—six hours, no more. And each man had a full six hours on his back, and there were three additional hours in the extra they'd take turns carrying. It was ample margin. But now the spare tank was left behind. There was no margin.

McCauley tried to lift the tank. But it had lain in the shadow of a boulder, out of the sun's fierce glare—on moon dust, radiating heat away toward the stars. It had cooled off to the temperature of a shadow, two hundred and forty degrees below zero. It was frozen. The air was liquid air. The tank was more brittle than glass was.

It slipped, striking the boulder. It cracked and broke. A glistening liquid poured out and evaporated instantly. Where it fell into shadow, part of it froze and then vanished more quickly than any earthly frost.

McCauley growled again. Air was precious on the moon. But there was no use crying when it was spilt. He turned around and began his journey again. He had good reason to worry now.

He was a singular, slow-motion soaring figure in a polished silvery space suit. Where there was a rise in the ground, he came smoothly up from behind it, the glaring sun glowing on his space armor. Extending one leg in what might pass as a version of a choreographer's arabesque, he came down on the extended foot and stepped on it, floating gently upward and forward swiftly in a continued series of seeming flights. He went through winding passes where the sledge trail was plain in the dust below him, he soared across preposterous areas strewn with boulders the size of apartment houses. Once, going through a narrow gap in the wall of an unnamed crater—a very small one, barely two miles across—he passed a spot which showed that the two men had changed places. The one in advance had gone to the rear, and the one who'd been behind now led the way.

It was just beyond the farther wall of the crater that he saw the second air tank, dropped in the trail.

It could not possibly be an accident. A moon sledge has racks for carrying air tanks. It was conceivable that a tank could have slid out and been lost unnoticed. But it was starkly inconceivable that it could have happened twice.

McCauley raged suddenly. He knew what had happened, he knew why it had happened, he knew who was involved. He flipped the base-frequency switch.

"Holmes! Kent! Come in!" he snapped. "Grimaldi Base, come in! Holmes! Kent! Come in! Grimaldi Base, come in!"

He did not try to pick up the second air tank. Instead, he increased his speed over the fantastic landscape of riven stone and upthrust rock. He went faster, floating twenty and thirty yards at a bound and calling angrily into the eternal silence about him. This higher speed was not particularly safe. A stumble on any of his landings could have meant a nasty crash and possibly a smashed helmet plate. But he raged on. He'd just traveled nearly a quarter of the way around the moon to try to effect the quiet and nonspectacular prevention of a murder. Now he found his trouble wasted, his precautions nullified, and the operation of his base imperiled. Moreover, the welfare of the men on Farside was threatened drastically. They might have to go through an entire lunar night, two weeks long, without any contact with other human beings.

Long, long minutes of speeded-up moon gait went by, the suit radio sending out snapped calls for Holmes and Kent to answer or, failing them, for Grimaldi Base to reply.

He was less than five miles from the base when he got an answer to his call. He'd climbed gradually to a high plateau which now dropped downward again so that what seemed an infinity of explosion-scarred desolation lay before him. He was in line of sight of Grimaldi.

"Grimaldi answers," said a voice in his helmet phones. "Grimaldi answers. Over."

Words fairly burst from McCauley's lips, though the rhythm of his twenty- and thirty-yard leaps remained unbroken.

"How in the blistering Gehenna," he rasped, "did Holmes and Kent get out of the base together? What fool sent them off?"

The voice in his headphones jerked a little.

"Why—it was your order, sir! A relay from Earth came in. Holmes was on monitor duty. He wrote down the order, sir. You ordered him and Kent to take the sledge with the relay unit for Repeater Two and set it up where it belonged, sir."

McCauley almost strangled in his wrath.

"Have they got there yet?"

"No, sir. They should use it to report that it's operating, sir. They haven't."

"When they do," rasped McCauley, "tell them that I specifically order them to stay in communication with you until I get there! Absolutely no excuse will be accepted for failure! I'm less than five miles off. I should get there in a quarter of an hour—twenty minutes at the outside. They think they're smart, but they've slipped up this time! Tell them that!"

"Y-yes, sir."

The headphone clicked.

McCauley uttered some profane words in the close confines of his space helmet. Back at Lunar Base he'd laid the matter of Holmes and Kent before the commanding officer, who was the ranking officer on the moon. Kent was an able young officer, transferred to Space Service from the Air Force. Holmes was also an able young officer, who'd been a submariner before he transferred to the equally confining Space Service. They'd known each other back on Earth and somehow—nobody knew how—a bitter and inveterate enmity had sprung up between them. Perhaps a girl was at the root of it, but if so, neither of them won her. Perhaps, by this time, the initial cause of their hatred had nearly or completely ceased to matter. Enmity does not often last unless things occur that can feed and strengthen it. It is normal for two young men to quarrel furiously and be ready to kill each other. But if they are separated long enough, their hatred usually dies away to acute dislike. In time the dislike fades to mere aversion or they may forget their anger altogether. But this happens when there is nothing to sustain and increase the quarrel.

On the other hand, if they come across each other often enough, and more especially if they try to harm each other, what could have begun as mere indignation and contempt can build up into a blind and murderous fury at the mere sight or thought of each other. How it started does not matter then. McCauley suspected that this was the case with Kent and Holmes.

Swinging up and soaring ahead, touching ground with precision at each landing and swinging up again to strange, wingless flight, McCauley muttered to himself.

They'd been assigned to his command. Not knowing—then—he'd introduced them. They spoke with great politeness but did not shake hands. Settling down to the routine and tedium of a six-man base, it became evident that there was something wrong. There was no overt trouble, but there was strain. It showed in a thousand trivial ways. When a party went out on an errand which required traveling for days in roasting sunlight, cased in space suits that were almost as confining as strait jackets, under conditions which rasped the nerves and tried the tempers of everybody, Holmes and Kent very nearly caused disasters.

Hatred blazed between them. When their records arrived at Grimaldi Base, McCauley realized that the beginning of this hatred could not matter any more. They'd hated each other so long and so bitterly that if they were asked the reason they'd have panted about something done yesterday or last month or last year—and perhaps never have gotten back to the beginning. They might even have forgotten it. But there was a strangeness in their enmity. They did not simply want disaster and misfortune to befall each other. They hungered to be disaster, they thirsted to be misfortune, each for the other. And somehow there was a demoniac pride involved. In the days of the duello there would have been a simple and normal solution. They would have met in stately fashion with swords or pistols, and they would have fought to the death under the eyes of seconds and witnesses, and somehow it would have been appropriate.

But such things were impossible now. The code of the duello was outmoded. So when McCauley read the records and reports on the two men—because a commanding officer needs to know the men who serve under him, and the more dangerous the service the better he needs to know them—he knew that the first case of murder on the moon was in the making. Since they couldn't fight formally, as in olden times, what must happen would amount to murder.

There'd been an automobile accident at Earth Base of the Space Service. It looked very much as if it were deliberate, as if Holmes and Kent had contrived it by agreement between themselves so that one was bound to be killed. Both were hurt. Neither died. Then there was the time when Kent was found with a rifle in his hand and a bullet wound in his shoulder, ignoring the wound and passionately pursuing a hunt for—so he said—a deer. He explained that the wound was an accident. The records showed that Holmes was hunting in the same area at the same time. They showed that he had a slight flesh wound—made by a bullet. Both Holmes and Kent gave totally unconvincing accounts of their wounds, and each denied that he had been wounded by the other. Their stories did not satisfy their commanding officer. He transferred them to other units, and in his confidential comment on their records—comment they would never see—he said that he believed they'd arranged a duel in deer-hunting country with big-game rifles, contrived so the one who was killed would seem to be the victim of a hunting accident. It could not be proved, but he believed it.

There were other memos. Neither Holmes nor Kent had a mark against him except in connection with the other man. Yet no commanding officer—certainly none on the moon—would want either man in his base after having read the records. The moon is too small for men who carry their enmities with them into space.

And McCauley had both men—able men, capable men, desirable men except for their mutual hatred. He'd traveled a quarter way around the moon to have one or both of them transferred out of Grimaldi Base before they could arrange another covered-up duel which would leave one dead and the other a murderer. But his effort had been futile. They couldn't be transferred out immediately. They couldn't be gotten out, for it was too close to sunset. They couldn't be gotten away at all during the lunar night. And now they were out on Farside where there could be no witnesses and the grave of a murdered man could never be found.

McCauley arrived, raging mad, at the small, grubby, dust-insulated dome that was Grimaldi Base. No report had come in from Kent or Holmes. McCauley was bitterly sure that they'd gone out to the blasted moonscape firmly resolved that only one of them would return. Somehow, in the illimitable emptiness of which the fiftieth part had never been seen by men, somehow, under the black, star-studded sky with the setting sun casting mile-long shadows of utter blackness and absolute cold, McCauley knew that they would have some sort of fight in which one must die.

But they were Space Service officers. Before they had that fight they would set up the relay that would give Farside Base a connection to Grimaldi, and so to Earth, and so by Earth Relay to every other human being on the moon. They would do their duty as Space Service officers before they did murder.

Stooping, McCauley came out of the air lock into the base.

"I want all the facts about Kent and Holmes!" he snapped.

"No word from them yet, sir," said the communications officer. "But we've picked up clickings, sir, which might be the unit being put into operation. But Holmes and Kent have two beams to align, sir, besides the all-direction antennae. They may be checking with Farside, sir, to make sure the relay beam is pointed right to that base."

McCauley stripped off his space suit.

"They're in more trouble than they know," he growled. "They lost two air tanks off their sledge."

The communications officer's mouth dropped open.

"But Colonel, sir.... They couldn't! They need those tanks to get back with!"

"Exactly," McCauley snapped. "Route the relay's local-antenna and suit-radio frequencies in to me. I'll take the messages."

He stamped through the cramped and shabby little base to the minute compartment set aside for the Base Commander's office. It was approximately four feet by six. He settled down in the one chair, glowering. Automatically he glanced at the dials that reported conditions at the base. Outside temperature facing sun, 198°. Shadow temperature, minus 205°. Inside barometric pressure, 30.02 inches. Inside temperature, 72°. Carbon monoxide, 28 parts per million. Carbon dioxide, 1.8%. Oxygen, 21.2%.

The physical state of the base was good. But there were two men out on Farside who lacked two tanks of air they needed to get back. Although it was their intention that only one of them should return, they'd outsmarted themselves. Neither could get back, now.

A clicking from a loud-speaker. A wavery voice:

"Calling Grimaldi Base! Calling Grimaldi! Call...."

"Calling Repeater Two," said McCauley. He was very grim. "Calling Repeater Two!"

"... rimaldi Ba...." Silence, then suddenly: "Hello!"

It was Holmes' voice. McCauley recognized it.

"Holmes!" he said curtly. "You two fools have committed suicide! You dropped one air tank off the sledge. Remember? That meant that only one of you could get back, and you and Kent could decide later which one it would be. But Kent kicked an air tank off, too! Now who's coming back?"

There was a startled silence.

"You heard me!" said McCauley savagely. "There were three tanks on that sledge. They'd bring you both back with air to spare. But you threw one away, and Kent threw one away, and so there's one left. It's six hours' travel back to here, and you've air for two men for four and a half!"