Collected Stories Of Arthur C. Clarke

by C. , Clarke, Arthur

  This was the second danger he had feared, and there was nothing he could do about it except to remain as inconspicuous as possible. The Doradus now had many eyes searching for him, but these auxiliaries had very severe limitations. They had been built to look for sunlit spaceships against a background of stars, not to search for a man hiding in a dark jungle of rock. The definition of their television systems was low, and they could only see in the forward direction.

  There were rather more men on the chess-board now, and the game was a little deadlier, but his was still the advantage.

  The torpedo vanished in the night sky. As it was travelling on a nearly straight course in this low-gravitational field, it would soon be leaving Phobos behind, and K.15 waited for what he knew must happen. A few minutes later, he saw a brief stabbing of rocket exhausts and guessed that the projectile was swinging slowly back on its course. At almost the same moment he saw another flare away in the opposite quarter of the sky and wondered just how many of these infernal machines were in action. From what he knew of Z-class cruisers – which was a good deal more than he should – there were four missile control channels, and they were probably all in use.

  He was suddenly struck by an idea so brilliant that he was quite sure it could not possibly work. The radio on his suit was a tunable one, covering an unusually wide band, and somewhere not far away the Doradus was pumping out power on everything from a thousand megacycles upwards. He switched on the receiver and began to explore.

  It came in quickly – the raucous whine of a pulse transmitter not far away. He was probably only picking up a sub-harmonic, but that was quite good enough. It D/F’ed sharply, and for the first time K.15 allowed himself to make long-range plans about the future. The Doradus had betrayed herself: as long as she operated her missiles, he would know exactly where she was.

  He moved cautiously forward towards the transmitter. To his surprise the signal faded, then increased sharply again. This puzzled him until he realised that he must be moving through a diffraction zone. Its width might have told him something useful if he had been a good enough physicist, but he could not imagine what.

  The Doradus was hanging about five kilometres above the surface in full sunlight. Her ‘non-reflecting’ paint was overdue for renewal, and K.15 could see her clearly. As he was still in darkness, and the shadow line was moving away from him, he decided that he was as safe here as anywhere. He settled down comfortably so that he could just see the cruiser and waited, feeling fairly certain that none of the guided projectiles would come so near the ship. By now, he calculated, the Commander of the Doradus must be getting pretty mad. He was perfectly correct.

  After an hour, the cruiser began to heave herself round with all the grace of a bogged hippopotamus. K.15 guessed what was happening. Commander Smith was going to have a look at the antipodes, and was preparing for the perilous fifty-kilometre journey. He watched very carefully to see the orientation the ship was adopting, and when she came to rest again was relieved to see that she was almost broadside on to him. Then, with a series of jerks that could not have been very enjoyable aboard, the cruiser began to move down to the horizon. K.15 followed her at a comfortable walking pace – if one could use the phrase – reflecting that this was a feat very few people had ever performed. He was particularly careful not to overtake her on one of his kilometre-long glides, and kept a close watch for any missiles that might be coming up astern.

  It took the Doradus nearly an hour to cover the fifty kilometres. This, as K.15 amused himself by calculating, represented considerably less than a thousandth of her normal speed. Once, she found herself going off into space at a tangent, and rather than waste time turning end over end again fired off a salvo of shells to reduce speed. But she made it at last, and K.15 settled down for another vigil, wedged between two rocks where he could just see the cruiser and he was quite sure she could not see him. It occurred to him that by this time Commander Smith might have great doubts as to whether he really was on Phobos at all, and he felt like firing off a signal flare to reassure him. However, he resisted the temptation.

  There would be little point in describing the events of the next ten hours, since they differed in no important detail from those that had gone before. The Doradus made three other moves, and K.15 stalked her with the care of the big-game hunter following the spoor of some elephantine beast. Once, when she would have led him out into full sunlight, he let her fall below the horizon until he could only just pick up her signals. But most of the time he kept her just visible, usually low down behind some convenient hill.

  Once a torpedo exploded some kilometres away, and K.15 guessed that some exasperated operator had seen a shadow he did not like – or else that a technician had forgotten to switch off a proximity fuse. Otherwise nothing happened to enliven the proceedings: in fact the whole affair was becoming rather boring. He almost welcomed the sight of an occasional guided missile drifting inquisitively overhead, for he did not believe that they could see him if he remained motionless and in reasonable cover. If he could have stayed on the part of Phobos exactly opposite the cruiser he would have been safe even from these, he realised, since the ship would have no control there in the Moon’s radio-shadow. But he could think of no reliable way in which he could be sure of staying in the safety zone if the cruiser moved again.

  The end came very abruptly. There was a sudden blast of steering-jets, and the cruiser’s main drive burst forth in all its power and splendour. In seconds the Doradus was shrinking sunwards, free at last, thankful to leave, even in defeat, this miserable lump of rock that had so annoyingly baulked her of her legitimate prey. K.15 knew what had happened, and a great sense of peace and relaxation swept over him. In the radar room of the cruiser, someone had seen an echo of disconcerting amplitude approaching with altogether excessive speed. K.15 now had only to switch on his suit beacon and to wait. He could even afford the luxury of a cigarette.

  ‘Quite an interesting story,’ I said, ‘and I see now how it ties up with that squirrel. But it does raise one or two queries in my mind.’

  ‘Indeed?’ said Rupert Kingman politely.

  I always like to get to the bottom of things, and I knew that my host had played a part in the Jovian War about which he seldom spoke. I decided to risk a long shot in the dark.

  ‘May I ask how you happen to know so much about this unorthodox military engagement? It isn’t possible, is it, that you were K.15?’

  There was an odd sort of strangling noise from Carson. Then Kingman said, quite calmly: ‘No, I wasn’t.’

  He got to his feet and went off towards the gun-room.

  ‘If you’ll excuse me a moment, I’m going to have another shot at that tree-rat. Maybe I’ll get him this time.’ Then he was gone.

  Carson looked at me as if to say: ‘This is another house you’ll never be invited to again.’ When our host was out of earshot he remarked in a coldly clinical voice:

  ‘You’ve torn it. What did you have to say that for?’

  ‘Well, it seemed a safe guess. How else could he have known all that?’

  ‘As a matter of fact, I believe he met K.15 after the War: they must have had an interesting conversation together. But I thought you knew that Rupert was retired from the Service with only the rank of Lieutenant-Commander. The Court of Inquiry could never see his point of view. After all, it just wasn’t reasonable that the Commander of the fastest ship in the Fleet couldn’t catch a man in a spacesuit.’

  Breaking Strain

  First published in Thrilling Wonder Stories, December 1949, as ‘Thirty Seconds – Thirty Days’

  Collected in Expedition to Earth

  Originally published in Thrilling Wonder Stories under the title ‘Thirty Seconds – Thirty Days’, ‘Breaking Strain’ was one of the stories incorporated into the film and novel, 2001.

  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, fo
r 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 if he were 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 smouldering 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 towards the doorway. McNeil did not offer to follow. Even making every allowance for the shock he had undergone, Grant felt 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 dumb-bell-shaped spaceship a hundred metres 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 aluminium paint, and the metal sides still held the faint touch of coldness that gave the only hint of their 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 essayed a faint attempt at humour.

  ‘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 all, 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 spacesuits!’ cried Grant in sudden excitement. ‘What about their tanks?’

  He had spoken without thinking, and the immediate realisation 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 seen 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 a 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 regenerator. Chuck me over the Manual, will you? I never remember how many cubic metres 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 over-simplified 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 who 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 centimetre across and weighing all of ten grams. According to the tables 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 thirty still to go. She was travelling, 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 street-car, 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 metres in diameter, joined by a cylinde
r about a hundred metres long. The whole structure looked like a matchstick-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 per second – and five months later she would be back at the orbit of the Earth, though Earth herself 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 proper solution – which had become almost a cliché – was to turn the ship into a glorified greenhouse or a hydroponics farm and let photosynthesis do the rest. Alternatively one could perform prodigies of chemical or atom 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 would 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.