The Space Trilogy

by Arthur C. Clarke

  Still two or three kilometres ahead, the great metal dome was glinting in the sunlight. From this angle, it had an astonishing appearance, for the segment in shadow was so dark as to be almost invisible. At first sight, indeed, it looked as if the dome had been bisected by some enormous knife. The whole place looked utterly deserted, but within, Steffanson knew, it would be a hive of furious activity. He prayed that his assistants had completed the wiring of the power and sub-modulator circuits.

  Steffanson began to adjust the helmet of his spacesuit, which he had not bothered to take off after entering the tractor. He stood behind Jamieson, holding on to one of the storage racks to steady himself.

  "Now that we're here," he said, "the least I can do is to let you understand what's happened." He gestured toward the rapidly approaching dome. "This place started as a mine, and it still is. We've achieved something that's never been done before—drilled a hole a hundred kilometres deep, right through the Moon's crust and down into really rich deposits of metal."

  "A hundred kilometres!" cried Wheeler. "That's impossible! No hole could stay open under the pressure."

  "It can and does," retorted Steffanson. "I've not time to discuss the technique, even if I knew much about it. But remember you can drill a hole six times as deep on the Moon as you can on Earth, before it caves in. However, that's only part of the story. The real secret lies in what they've called pressure-mining. As fast as it's sunk, the well is filled with a heavy silicone oil, the same density as the rocks around it. So no matter how far down you go, the pressure is the same inside as out, and there's no tendency for the hole to close. Like most simple ideas, it's taken a lot of skill to put it into practice. All the operating equipment has to work submerged, under enormous pressure, but the problems are being overcome and we believe we can get metals out in worthwhile quantities.

  "The Federation learned this was going on about two years ago. We believe they've tried the same thing, but without any luck. So they're determined that if they can't share this hoard, we won't have it either. Their policy seems to be one of bullying us into co-operation, and it's not going to work.

  "That's the background, but now it's only the less important part of the story. There are weapons here as well. Some have been completed and tested, others are waiting for the final adjustments. I'm bringing the key components for what may be the decisive one. That's why Earth may owe you a greater debt than it can ever pay. Don't interrupt—we're nearly there and this is what I really want to tell you. The radio was not telling the truth about that twenty hours of safety. That's what the Federation wants us to believe, and we hope they go on thinking we've been fooled. But we've spotted their ships, and they're approaching ten times as fast as anything that's ever moved through space before. I'm afraid they've got a fundamental new method of propulsion—I only hope it hasn't given them new weapons as well. We've not much more than three hours before they get here—assuming they don't step up their speed still further. You could stay, but for your own safety I advise you to turn around and drive like hell back to the Observatory. If anything starts to happen while you're still out in the open, get under cover as quickly as possible. Go down into a crevasse—anywhere you can find shelter—and stay there until it's all over. Now good-by and good luck. I hope we have a chance of meeting again, when this business is finished."

  Still clutching his mysterious packing case, Steffanson disappeared into the airlock before either of the men could speak. They were now entering the shadows of the great dome, and Jamieson circled it looking for an opening. Presently he recognized the spot through which he and Wheeler had made their entrance, and brought Ferdinand to a halt.

  The outer door of the tractor slammed shut and the "Airlock Clear" indicator flashed on. They saw Steffanson running across toward the dome, and with perfect timing a circular port flipped open to let him in, then snapped shut behind him.

  The tractor was alone in the building's enormous shadow. Nowhere else was there any sign of life, but suddenly the metal framework of the machine began to vibrate at a steadily rising frequency. The meters on the control panel wavered madly, the lights dimmed, and then it was all over. Everything was normal again, but some tremendous field of force had swept out from the dome and was even now expanding into space. It left the two men with an overwhelming impression of energies awaiting the signal for their release. They began to understand the urgency of Steffanson's warning. The whole deserted landscape seemed tense with expectation.

  Across the steeply curving plain, the tiny beetle of the tractor raced for the safety of the distant hills. But could they be sure of safety even there? Jamieson doubted it. He remembered the weapons that science had made more than two centuries ago; they would be merely the foundation upon which the arts of war could build today. The silent land around him, now burning beneath the noonday sun, might soon be blasted by radiations fiercer still.

  He drove forward into the shadow of the tractor, toward the ramparts of Plato, towering along the skyline like some fortress of the giants. But the real fortress was behind him, preparing its unknown weapons for the ordeal that must come.

  Sixteen

  It would never have happened had Jamieson been thinking more of driving and less of politics—though, in the circumstances, he could hardly be blamed. The ground ahead looked level and firm—exactly the same as the kilometres they had already safely traversed.

  It was level, but it was no firmer than water. Jamieson knew what had happened the moment that Ferdinand's engine started to race, and the tractor's nose disappeared in a great cloud of dust. The whole vehicle tilted forward, began to rock madly to and fro, and then lost speed despite all that Jamieson could do. Like a ship foundering in a heavy sea, it started to sink. To Wheeler's horrified eyes, they seemed to be going under in swirling clouds of spray. Within seconds, the sunlight around them had vanished. Jamieson had stopped the motor; in a silence broken only by the murmur of the air circulators, they were sinking below the surface of the Moon.

  The cabin lights came on as Jamieson found the switch. For a moment, both men were too stunned to do anything but sit and stare helplessly at each other. Then Wheeler walked, not very steadily, to the nearest observation window. He could see absolutely nothing: no night was ever as dark as this. A smooth velvet curtain might have been brushing the other side of the thick quartz, for all the light that could penetrate it.

  Suddenly, with a gentle but distinct bump, Ferdinand reached the bottom.

  "Thank God for that," breathed Jamieson. "It's not very deep."

  "What good does that do us?" asked Wheeler, hardly daring to believe there was any hope. He had heard too many horrifying tales of these treacherous dust bowls, and the men and tractors they had engulfed.

  The lunar dust-bowls are, fortunately, less common than might be imagined from some travellers' tales, for they can occur only under rather special conditions, which even now are not fully understood. To make one, it is necessary to start with a shallow crater pit in the right kind of rock, and then wait a few hundred million years while the temperature changes between night and day slowly pulverize the surface layers. As this age-long process continues, so a finer and finer grade of dust is produced, until at last it begins to flow like a liquid and accumulates at the bottom of the crater. In almost all respects, indeed, it is a liquid: it is so incredibly fine that if collected in a bucket, it will slop around like a rather mobile oil. At night one can watch convection currents circulating in it, as the upper layers cool and descend, and the warmer dust at the bottom rises to the top. This effect makes dust-bowls easy to locate, since infra-red detectors can "see" their abnormal heat radiation at distances of several kilometres. However, during the daytime this method is useless owing to the masking effect of the sun.

  "There's no need to get alarmed," said Jamieson, though he looked none too happy. "I think we can get out of this. It must be a very small bowl, or it would have been spotted before. This area's supposed to have been thorou
ghly marked."

  "It's big enough to have swallowed us."

  "Yes, but don't forget what this stuff's like. As long as we can keep the motors running, we have a chance of pushing our way out—like a submarine-tank making its way up on to shore. The thing that bothers me is whether we should go ahead, or try and back out."

  "If we go ahead, we might get in deeper."

  "Not necessarily. As I said, it must be a pretty small bowl and our momentum may have carried us more than halfway across it. Which way would you say the floor is tilted now?"

  "The front seems to be a bit higher than the rear."

  "That's what I thought. I'm going ahead—we can get more power that way, too."

  Very gently, Jamieson engaged the clutch in the lowest possible gear. The tractor shook and protested, then lurched forward a few centimetres, then halted again.

  "I was afraid of that," said Jamieson. "I can't keep up a steady progress. We'll have to go in jerks. Pray for the engine—not to mention the transmission."

  They jolted their way forward in agonizingly slow surges, then Jamieson cut the engine completely.

  "Why did you do that?" Wheeler asked anxiously. "We seemed to be getting somewhere."

  "Yes, but we're also getting too hot. This dust is an almost perfect heat insulator. We'll have to wait a minute until we cool off."

  Neither felt like making any conversation as they sat in the brightly lit cabin that might well, Wheeler reflected, become their tomb. It was ironic that they had encountered this mishap while they were racing for safety.

  "Do you hear that noise?" said Jamieson suddenly. He switched off the air circulator, so that complete silence fell inside the cab.

  There was the faintest of sounds coming through the walls. It was a sort of whispering rustle, and Wheeler could not imagine what it was.

  "The dust's starting to rise. It's highly unstable, you know, and even a small amount of heat is enough to start convection currents. I expect we're making quite a little geyser up at the top—it will help anyone to find us if they come and look."

  That was some consolation, at any rate. They had air and food for many days—all tractors carried a large emergency reserve—and the Observatory knew their approximate position. But before long the Observatory might have trouble of its own, and would be unable to bother about them…

  Jamieson re-started the motor, and the sturdy vehicle started to butt its way forward again through the dry quicksand that enveloped them. It was impossible to tell how much progress they were making, and Wheeler dared not imagine what would happen if the motors failed. The caterpillar treads were grinding at the rock beneath them, and the whole tractor shook and groaned under the intolerable load.

  It was almost an hour before they were certain they were getting somewhere. The floor of the tractor was definitely tilting upward, but there was no way of telling how far below the quasi-liquid surface they were still submerged. They might emerge at any moment into the blessed light of day—or they might have a hundred meters still to traverse at this snail-like pace.

  Jamieson was stopping for longer and longer intervals, which might reduce the strain on the engine but did nothing to reduce that on the passengers. During one of these pauses Wheeler asked him outright what they should do if they could get no further.

  "We've only two possibilities," Jamieson answered. "We can stay here and hope to be rescued—which won't be as bad as it sounds, since our tracks will make it obvious where we are. The other alternative is to go out."

  "What! That's impossible!"

  "Not at all. I know a case where it's been done. It would be rather like escaping from a sunken submarine."

  "It's a horrible thought—trying to swim through this stuff."

  "I was once caught in a snowdrift when I was a kid, so I can guess what it would be like. The great danger would be losing your direction and floundering around in circles until you were exhausted. Let's hope we don't have to try the experiment."

  It was a long time, Wheeler decided, since he had heard a bigger understatement than that.

  The driving cab emerged above the dust level about an hour later, and no men could ever have greeted the sun with such joy. But they had not yet reached safety; though Ferdinand could make better speed as the resistance slackened, there might still be unsuspected depths ahead of them.

  Wheeler watched with fascinated repulsion as the horrible stuff eddied past the tractor. At times it was quite impossible to believe that they were not forcing their way through a liquid, and only the slowness with which they moved spoiled the illusion. He wondered if it was worth suggesting that in future Caterpillars have better streamlining to improve their chances in emergencies like this. Who would ever have dreamed, back on Earth, that that sort of thing might be necessary?

  At last Ferdinand crawled up to the security of the dry land, which, after all, was no drier than the deadly lake from which they had escaped. Jamieson, almost exhausted by the strain, slumped down across the control panel. The reaction had left Wheeler shaken and weak, but he was too thankful to be out of danger to let that worry him.

  He had forgotten, in the relief of seeing sunlight again, that they had left Project Thor three hours ago, and had covered less than twenty kilometres.

  Even so, they might have made it. But they had just started on their way again, and were crawling over the top of a quite gentle ridge, when there was a scream of tearing metal and Ferdinand tried to spin round in a circle. Jamieson cut the motor instantly and they came to rest broadside-on to their direction of motion.

  "And that," said Jamieson softly, "is most definitely that. But I don't think we're in a position to grumble. If the starboard transmission had sheared while we were still in that dust-bowl—" He didn't finish the sentence, but turned to the observation port that looked back along their trail. Wheeler followed his gaze.

  The dome of Project Thor was still visible on the horizon. Perhaps they had already strained their luck to the utmost—but it would have been nice could they have put the protecting curve of the Moon clear between themselves and the unknown storms that were brewing there.

  Seventeen

  Even today, little has ever been revealed concerning the weapons used in the Battle of Pico. It is known that missiles played only a minor part in the engagement. In space warfare, anything short of a direct hit is almost useless, since there is nothing to transmit the energy of a shock wave. An atom bomb exploding a few hundred meters away can cause no blast damage, and even its radiation can do little harm to well-protected structures. Moreover, both Earth and the Federation had effective means of diverting ordinary projectiles.

  Purely non-material weapons would have to play the greatest role. The simplest of these were the ion-beams, developed directly from the drive-units of spaceships. Since the invention of the first radio tubes, almost three centuries before, men had been learning how to produce and focus ever more concentrated streams of charged particles. The climax had been reached in spaceship propulsion with the so-called "ion rocket," generating its thrust from the emission of intense beams of electrically charged particles. The deadliness of these beams had caused many accidents in space, even though they were deliberately defocused to limit their effective range.

  There was, of course, an obvious answer to such weapons. The electric and magnetic fields which produced them could also be used for their dispersion, converting them from annihilating beams into a harmless, scattered spray.

  More effective, but more difficult to build, were the weapons using pure radiation. Yet even here, both Earth and the Federation had succeeded. It remained to be seen which had done the better job—the superior science of the Federation, or the greater productive capacity of Earth.

  Commodore Brennan was well aware of all these factors as his little fleet converged upon the Moon. Like all commanders, he was going into action with fewer resources than he would have wished. Indeed, he would very much have preferred not to be going into action at
all.

  The converted liner Eridanus and the largely rebuilt freighter Lethe—once listed in Lloyd's register as the Morning Star and the Rigel—would now be swinging in between Earth and Moon along their carefully plotted courses. He did not know if they still had the element of surprise. Even if they had been detected, Earth might not know of the existence of this third and largest ship, the Acheron. Brennan wondered what romantic with a taste for mythology was responsible for these names—probably Commissioner Churchill, who made a point of emulating his famous ancestor in as many ways as he possibly could. Yet they were not inappropriate. The rivers of Death and Oblivion—yes, these were things they might bring to many men before another day had passed.

  Lieutenant Curtis, one of the few men in the crew who had actually spent most of his working life in space, looked up from the communications desk.

  "Message just picked up from the Moon, sir. Addressed to us."

  Brennan was badly shaken. If they had been spotted, surely their opponents were not so contemptuous of them that they would freely admit the fact! He glanced quickly at the signal, then gave a sigh of relief.

  OBSERVATORY TO FEDERATION. WISH TO REMIND YOU OF EXISTENCE IRREPLACEABLE INSTRUMENTS PLATO. ALSO ENTIRE OBSERVATORY STAFF STILL HERE. MACLAURIN. DIRECTOR.

  "Don't frighten me like that again, Curtis," said the commodore. "I thought you meant it was beamed at me. I'd hate to think they could detect us this far out."

  "Sorry, sir. It's just a general broadcast. They're still sending it out on the Observatory wavelength."

  Brennan handed the signal over to his operations controller, Captain Merton.

  "What do you make of this? You worked there, didn't you?"