Arthur C Clarke - Breaking Strain Read online

  Breaking Strain

  Arthur C. Clarke

  1949

  Originally Published as "Thirty Seconds - Thirty Days"

  Grant was writing up the Star Queen's log when he heard the cabin door opening behind him. He didn't bother to look round-it was hardly necessary for there was only one other man aboard the ship. But when nothing happened, and when McNeil neither spoke nor came into the room, the long silence finally roused Grant's curiosity and he swung the seat round in its gimbals.

  McNeil was just standing in the doorway, looking as if he had seen a ghost. The trite metaphor flashed into Grant's mind instantly. He did not know for a moment how near the truth it was. In a sense McNeil had seen a ghost-the most terrifying of all ghosts -his own.

  "What's the matter?" said Grant angrily. "You sick or something?"

  The engineer shook his head. Grant noticed the little beads of sweat that broke away from his forehead and went glittering across the room on their perfectly straight trajectories. His throat muscles moved, but for a while no sound came. It looked as though he was going to cry.

  "We're done for," he whispered at last. "Oxygen reserve's gone."

  Then he did cry. He looked like a flabby doll, slowly collapsing on itself. He couldn't fall, for there was no gravity, so he just folded up in mid-air.

  Grant said nothing. Quite unconsciously he rammed his smoldering cigarette into the ash tray, grinding it viciously until the last tiny spark had died. Already the air seemed to be thickening

  around him as the oldest terror of the spaceways gripped him by

  the throat.

  He slowly loosed the elastic straps which, while he was seated, gave some illusion of weight, and with an automatic skill launched himself toward the doorway. McNeil did not offer to follow. Even making every allowance for the shock he had undergone, Grant felt that he was behaving very badly. He gave the engineer an angry cuff as he passed and told him to snap out of it.

  The hold was a large hemispherical room with a thick central column which carried the controls and cabling to the other half of the dumbbell-shaped spaceship a hundred meters away. It was packed with crates and boxes arranged in a surrealistic three-dimensional array that made very few concessions to gravity.

  But even if the cargo had suddenly vanished Grant would scarcely have noticed. He. had eyes only for the big oxygen tank, taller than himself, which was bolted against the wall near the inner door of the airlock.

  It was just as he had last seen it, gleaming with aluminum paint, and the metal sides still held the faint touch of coldness that gave the only hint of the contents. All the piping seemed in perfect condition. There was no sign of anything wrong apart from one minor detail. The needle of the contents gauge lay mutely against the zero stop.

  Grant gazed at that silent symbol as a man in ancient London, returning home one evening at the time of the Plague, might have stared at a rough cross newly scrawled upon his door. Then he banged half a dozen times on the glass in the futile hope that the needle had stuck-though he never really doubted its message. News that is sufficiently bad somehow carries its own guarantee of truth. Only good reports need confirmation.

  When Grant got back to the control room, McNeil was himself again. A glance at the opened medicine chest showed the reason for the engineer's rapid recovery. He even assayed a faint attempt at humor.

  "It was a meteor," he said. "They tell us a ship this size should get hit once a century. We seem to have jumped the gun with ninety-five years still to go.,,

  "But what about the alarms? The air pressure's normal-how could we have been holed?"

  "We weren't," McNeil replied. "You know how the oxygen circulates night-side through the refrigerating coils to keep it liquid? The meteor must have smashed them and the stuff simply boiled away."

  Grant was silent, collecting his thoughts. What had happened was serious-deadly serious-but it need not be fatal. After an, the voyage was more than three quarters over.

  "Surely the regenerator can keep the air breathable, even if it does get pretty thick?" he asked hopefully.

  McNeil shook his head. "I've not worked it out in detail, but I know the answer. When the carbon dioxide is broken down and the free oxygen gets cycled back there's a loss of about ten per cent. That's why we have to carry a reserve."

  "The space-suits!" cried Grant in sudden excitement. "What about their tanks?"

  He had spoken without thinking, and the immediate realization of his mistake left him feeling worse than before.

  "We can't keep oxygen in them-it would boil off in a few days. There's enough compressed gas there for about thirty minutes merely long enough for you to get to the main tank in an emergency."

  "There must be a way out-even if we have to jettison cargo and run for it. Let's stop guessing and work out exactly where we are."

  Grant was as much angry as frightened. He was angry with McNeil for breaking down. He was angry with the designers of the ship for not having foreseen this God-knew-how-many-million-to-one chance. The deadline might be a couple of weeks away and a lot could happen before then. The thought helped for a moment to keep his fears at arm's length.

  This was an emergency, beyond doubt, but it was one of those peculiarly protracted emergencies that seem to happen only in space. There was plenty of time to think-perhaps too much time.

  Grant strapped himself in the pilot's seat and pulled~ out a writing-pad.

  "Let's get the facts right," he said with artificial calmness. "We've got the air that's still circulating in the ship and we lose ten per cent of the oxygen every time it goes through the generator. Chuck me over the Manual, will you? I can never remember how many cubic meters we use a day."

  In saying that the Star Queen might expect to be hit by a meteor once every century, McNeil had grossly but unavoidably oversimplified the problem. For the answer depended on so many factors that three generations of statisticians had done little but lay down rules so vague that the insurance companies still shivered with apprehension when the great meteor showers went sweeping like a gale through the orbits of the inner worlds.

  Everything depends, of course, on what one means by the word meteor. Each lump of cosmic slag that reaches the surface of the Earth has a million smaller brethren that perish utterly in the no man's-land where the atmosphere has not quite ended and space has yet to begin-that ghostly region where the weird Aurora sometimes walks by night.

  These are the familiar shooting stars, seldom larger than a pin's head, and these in turn are outnumbered a million fold again by particles too small to leave any visible trace of their dying as they drift down from the sky. All of them, the countless specks of dust, the rare boulders and even the wandering mountains that Earth encounters perhaps once every million years-all of them are meteors.

  For the purposes of space-flight, a meteor is only of interest if, on penetrating the hull of a ship, it leaves a hole large enough to be dangerous. This is a matter of relative speeds as well as size. Tables have been prepared showing approximate collision times for various parts of the Solar System-and for various sizes of meteors down to masses of a few milligrams.

  That which had struck the Star Queen was a giant, being nearly a centimeter across and weighing all of ten grams. According to the table the waiting-time for collision with such a monster was of the order of ten to the ninth days-say three million years. The virtual certainty that such an occurrence would not happen again in the course of human history gave Grant and McNeil very little consolation.

  However, things might have been worse. The Star Queen was 115 days on her orbit and had only 30 still to go. She was traveling, as did all freighters, on the long
tangential ellipse kissing the orbits of Earth and Venus on opposite sides of the Sun. The fast liners could cut across from planet to planet at three times her speed and ten times her fuel consumption-but she must plod along her

  predetermined track like a streetcar, taking 145 days, more or less, for each journey.

  Anything more unlike the early-twentieth-century idea of a spaceship than the Star Queen would be hard to imagine. She consisted of two spheres, one fifty and the other twenty meters in diameter, joined by a cylinder about a hundred meters long. The whole structure looked like a match-stick-and-Plasticine model of a hydrogen atom. Crew, cargo, and controls were in the larger sphere, while the smaller one held the atomic motors and was-to put it mildly-out of bounds to living matter.

  The Star Queen had been built in space and could never have lifted herself even from the surface of the Moon. Under full power her ion drive could produce an acceleration of a twentieth of a gravity, which in an hour would give her all the velocity she needed to change from a satellite of the Earth to one of Venus.

  Hauling cargo up from the planets was the job of the powerful little chemical rockets. In a month the tugs would be climbing up from Venus to meet her, but the Star Queen would not be stopping for there would be no one at the controls. She would continue blindly on her orbit, speeding past Venus at miles a second-and five months later she would be back at the orbit of the Earth, though Earth itself would then be far away.

  It is surprising how long it takes to do a simple addition when your life depends on the answer. Grant ran down the short column of figures half a dozen times before he finally gave up hope that the total would change. Then he sat doodling nervously on the white plastic of the pilot's desk.

  "With all possible economies," he said, "we can last about twenty days. That means we'll be ten days out of Venus when.

  His voice trailed off into silence.

  Ten days didn't sound much-but it might just as well have been ten years. Grant thought sardonically of all the hack adventure writers who had used just this situation in their stories and radio serials. In these circumstances, according to the carbon-copy experts-few of whom had ever gone beyond the Moon-there were three things that could happen.

  The popular solution-which had become almost a cliché-was to turn the ship into a glorified greenhouse or a hydroponic farm

  and let photosynthesis do the rest. Alternatively one could perform prodigies of chemical or atomic engineering-explained in tedious technical detail-and build an oxygen manufacturing plant which would not only save your life-and of course the heroine's-but also make you the owner of fabulously valuable patents. The third or deus ex machina solution was the arrival of a convenient spaceship which happened to be matching your course and velocity exactly.

  But that was fiction and things were different in real life. Although the first idea was sound in theory there wasn't even a packet of grass seed aboard the Star Queen. As for feats of inventive engineering, two men-however brilliant and however desperate were not likely to improve in a few days on the work of scores of great industrial research organizations over a full century.

  The spaceship that "happened to be passing" was, almost by

  definition, impossible. Even if other freighters had been coasting

  on the same elliptic path-and Grant knew there were none-then by

  the very laws that governed their movements they would always

  keep their original separations. It was not quite impossible that a

  liner, racing on its hyperbolic orbit, might pass within a few hundred thousand kilometers of them-but at a speed so great that it

  would be as inaccessible as Pluto.

  "If we threw out the cargo," said McNeil at last, "would we have a chance of changing our orbit?"

  Grant shook his head.

  "I'd hoped so," he replied, "but it won't work. We could reach Venus in a week if we wished-but we'd have no fuel for braking and nothing from the planet could catch us as we went past."

  "Not even a liner?"

  "According to Lloyd's Register Venus has only a couple of freighters at the moment. In any case it would be a practically impossible maneuver. Even if it could match our speed how would the rescue ship get back? It would need about fifty kilometers a second for the whole job!"

  "If we can't figure a way out," said McNeil, "maybe someone on Venus can. We'd better talk to them."

  "I'm going to," Grant replied, "as soon as I've decided what to say. Go and get the transmitter aligned, will you?"

  He watched McNeil as he floated out of the room. The engineer was probably going to give trouble in the days that lay ahead. Until

  now they had got on well enough-like most stout men McNeil was good-natured and easygoing. But now Grant realized that he lacked fiber. He had become flabby-physically and mentally living too long in space.

  A buzzer sounded on the transmitter switchboard. The parabolic mirror out on the hull was aimed at the gleaming arc-lamp of Venus, only ten million kilometers away and moving on an almost parallel path. The three-millimeter waves from the ship's transmitter would make the trip in little more than half a minute. There was bitterness in the knowledge that they were only thirty seconds from safety.

  The automatic monitor on Venus gave its impersonal Go ahead signal and Grant began to talk steadily, and he hoped, quite dispassionately. He gave a careful analysis of the situation and ended with a request for advice. His fears concerning McNeil he left unspoken. For one thing he knew that the engineer would be monitoring him at the transmitter.

  As yet no one on Venus would have heard the message, even though the transmission time4ag was over. It would still be coiled up in the recorder spools, but in a few minutes an unsuspecting signal officer would arrive to play it over.

  He would have no idea of the bombshell that was about to burst, triggering trains of sympathetic ripples on all the inhabited worlds as television and newssheet took up the refrain. An accident in space has a dramatic quality that crowds all other items from the headlines.

  Until now Grant had been too preoccupied with his own safety to give much thought to the cargo in his charge. A sea captain of ancient times, whose first thought was for his ship, might have been shocked by this attitude. Grant, however, had reason on his side.

  The Star Queen could never founder, could never run upon uncharted rocks or pass silently, as so many ships have passed, forever from the knowledge of man. She was safe, whatever might befall her crew. If she was undisturbed she would continue to retrace her orbit with such precision that men might set their calendars by her for centuries to come.

  The cargo, Grant suddenly remembered, was insured for over twenty million dollars. There were not many goods valuable enough

  to be shipped from world to world and most of the crates in the hold were worth more than their weight-or rather their mass-in gold. Perhaps some items might be useful in this emergency and Grant went to the safe to find the loading schedule.

  He was sorting the thin, tough sheets when McNeil came back into the cabin.

  "I've been reducing the air pressure," he said. "The hull shows some leaks that wouldn't have mattered in the usual way."

  Grant nodded absently as he passed a bundle of sheets over to McNeil.

  "Here's our loading schedule. I suggest we both run through it in case there's anything in the cargo that may help."

  if it did nothing else, he might have added, it would at least give them something to occupy their minds.

  As he ran down the long columns of numbered items-a complete cross-section of interplanetary commerce-Grant found himself wondering what lay behind these inanimate symbols. item 347 - 1 book - 4 kilos gross.

  He whistled as he noticed that it was a staffed item, insured for a hundred thousand dollars, and he suddenly remembered hearing on the radio that the Hesperian Museum had just bought a first edition Seven Pillars of Wisdom.

  A few sheets later was a very contrasting item, Miscellaneous bo
oks - 25 kilos - no intrinsic value.

  It had cost a small fortune to ship those books to Venus, yet they were of "no intrinsic value." Grant let his imagination loose on the problem. Perhaps someone who was leaving Earth forever was taking with him to a new world his most cherished treasures-the dozen or so volumes that above all others had most shaped his mind.

  Item 564 - 12 reels film.

  That, of course, would be the Neronian super-epic, While Rome Burns, which had left Earth just one jump ahead of the censor. Venus was waiting for it with considerable impatience.

  Medical supplies - 50 kilos. Case of cigars - I kilo. Precision instruments - 75 kilos. So the list went on. Each item was something rare or something which the industry and science of a younger civilization could not yet produce.

  The cargo was sharply divided into two classes-blatant luxury or sheer necessity. There was little in between. And there was