Earthlight (Arthur C. Clarke Collection) Read online

  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.

  Chapter XVII

  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

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  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.

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

  Brerman 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?"

  Merton smiled as he read the message.

  "Just like Maclaurin. Instruments first, staff second. I'm not too worried. I'll do my damnedest to miss him. A hundred kilometers isn't a bad safety margin, when you come to think of it. Unless there's a direct hit with a stray, they've nothing to worry about. They're pretty well dug in, you know."

  The relentless hand of the chronometer was scything away the last minutes. Still confident that his ship, encased in its cocoon of night, had not yet been detected, Commodore Bren­nan watched the three sparks of his fleet creep along their ap­pointed tracks in the plotting sphere. This was not a destiny he had ever imagined would be his—to hold the fate of worlds within his hands.

  But he was not thinking of the powers that slumbered in the reactor banks, waiting for his command. He was not concerned with the place he would take in history, when men looked back upon this day. He only wondered, as had all who had ever faced battle for the first time, where he would be this same time to­morrow.

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  Less than a million kilometers away, Carl Steffanson sat at a control desk and watched the image of the sun, picked up by one of the many cameras that were the eyes of Project Thor. The group of tired technicians standing around him had almost com­pleted the equipment before his arrival; now the discriminating units he had brought from Earth in such desperate haste had been wired into the circuit.

  Steffanson turned a knob, and the sun went out. He flicked from one camera position to another, but all the eyes of the fortress were equally blind. The coverage was complete.

  Too weary to feel any exhilaration, he leaned back in his seat and gestured toward the controls.

  "It's up to you now. Set it to pass enough light for vision, but to give total rejection from the ultra-violet upward. We're sure none of their beams carry any effective power much beyond a thousand Angstroms. They'll be very surprised when all their stuff bounces off. I only wish we could send it back the way it came."

  "Wonder what we look like from outside when the screen's on?" said one of the engineers.

  "Just like a perfectly reflecting mirror. As long as it keeps reflecting, we're safe against pure radiation. That's all I can promise you."

  Steffanson looked at his watch.

  "If Intelligence is correct, we have about twenty minutes to spare. But I shouldn't count on it."

  "At least Maclaurin knows where we are now," said Jamieson as he switched off the radio. "But I can't blame him for not sending someone to pull us out."

  "Then what do we do now?"

  "Get some food," Jamieson answered, walking back to the tiny galley. "I think we've earned it, and there may be a long walk ahead of us."

  Wheeler looked nervously across the plain, to the distant but all too clearly visible dome of Project Thor. Then his jaw dropped and it was some seconds before he could believe that his eyes were not playing tricks on him.

  "Sid!" he called. "Come and look at this!"

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  Jamieson joined him at a rush, and together they stared out toward the horizon. The partly shadowed hemisphere of the dome had changed its appearance completely. Instead of a thin crescent of light, it now showed a single dazzling star, as though the image of the sun was being reflected from a perfectly spheri­cal mirror surface.

  The telescope confirmed this impression. The dome itself was no longer visible; its place seemed to have been taken by this fantastic silver apparition. To Wheeler it looked exactly like a great blob of mercury sitting on the skyline.

  "I'd like to know how they've done that," was Jamieson's un-excited comment. "Some kind of interference effect, I suppose. It must be part of their defense system."

  "We'd better get moving," said Wheeler anxiously. "I don't like the look of this. It feels horribly exposed up here."

  Jamieson had started throwing open cupboards and pulling out stores. He tossed some bars of chocolate and packets of com­pressed meat over to Wheeler.

  "Start chewing some of this," he said. "We won't have time for a proper meal now. Better have a drink as well, if you're thirsty. But don't take
too much—you'll be in that suit for hours, and these aren't luxury models."

  Wheeler was doing some mental arithmetic. They must be about eighty kilometers from base, with the entire rampart of Plato between them and the Observatory. Yes, it would be a long walk home, and they might after all be safer here. The tractor, which had already served them so well, could protect them from a good deal of trouble.

  Jamieson toyed with the idea, but then rejected it. "Remem­ber what Steffanson said," he reminded Wheeler. "He told us to get underground as soon as we could. And he must know what he's talking about."

  They found a crevasse within fifty meters of the tractor, on the slope of the ridge away from the fortress. It was just deep enough to see out of when they stood upright, and the floor was sufficiently level to lie down. As a slit trench, it might almost have been made to order, and Jamieson felt much happier when he had located it.

  "The only thing that worries me now," he said, "is how long

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  we may have to wait. It's still possible that nothing will happen at all. On the other hand, if we start walking we may be caught in the open away from shelter."

  After some discussion, they decided on a compromise. They would keep their suits on, but would go back and sit in Ferdi­nand where at least they would be comfortable. It would take them only a few seconds to get to the trench.

  There was no warning of any kind. Suddenly the gray, dusty rocks of the Sea of Rains were scorched by a light they had never known before in all their history. Wheeler's first impression was that someone had turned a giant searchlight full upon the trac­tor ; then he realized that this sun-eclipsing explosion was many kilometers away. High above the horizon was a ball of violet flame, perfectly spherical, and rapidly losing brilliance as it ex­panded. Within seconds, it had faded to a great cloud of lumi­nous gas. It was dropping down toward the edge of the Moon, and almost at once had sunk below the skyline like some fan­tastic sun.

  "We were fools," said Jamieson gravely. "That was an atomic warhead—we may be dead men already."

  "Nonsense," retorted Wheeler, though without much confi­dence. "That was fifty kilometers away. The gammas would be pretty weak by the time they reached us—and these walls aren't bad shielding."

  Jamieson did not answer; he was already on his way to the airlock. Wheeler started to follow him, then remembered that there was a radiation detector aboard and went back to collect it. Was there anything else that might be useful while he was here? On a sudden impulse, he jerked down the curtain-rod above the little alcove that concealed the lavatory, then ripped away the wall mirror over the sink.

  When he joined Jamieson, who was waiting impatiently for him in the airlock, he handed over the detector, but did not bother to explain the rest of his equipment. Not until they had settled down in their trench, which they reached without further incident, did he make its purpose clear.

  "If there's one thing I hate," he said petulantly, "it's not being able to see what's going on." He started to fix the mirror to the curtain rod, using some wire from one of the pouches

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  round his suit. After a couple of minutes' work, he was able to hoist a crude periscope out of the hole.

  "I can just see the dome," he said with some satisfaction. "It's quite unchanged, as far as I can tell."

  "It would be," Jamieson replied. "They must have managed to explode that bomb somehow while it was miles away."

  "Perhaps it was only a warning shot."

  "Not likely! No one wastes plutonium for firework displays. That meant business. I wonder when the next move is going to be?"

  It did not come for another five minutes. Then, almost simul­taneously, three more of the dazzling atomic suns burst against the sky. They were all moving on trajectories that took them toward the dome, but long before they reached it they had dispersed into tenuous clouds of vapor.

  "Rounds one and two to Earth," muttered Wheeler. "I won­der where these missiles are coming from?"

  "If any of them burst directly overhead," said Jamieson, "we will be done for. Don't forget that there's no atmosphere to ab­sorb the gammas here."

  "What does the radiation meter say?"

  "Nothing much yet, but I'm worried about that first blast, when we were still in the tractor."

  Wheeler was too busily searching the sky to answer. Some­where up there among the stars, which he could see now that he was out of the direct glare of the sun, must be the ships of the Federation, preparing for the next attack. It was not likely that the ships themselves would be visible, but he might be able to see their weapons in action.

  From somewhere beyond Pico, six sheaves of flame shot up into the sky at an enormous acceleration. The dome was launch­ing its first missiles, straight into the face of the sun. The Lethe and the Eridanus were using a trick as old as warfare itself; they were approaching from a direction in which their opponent would be partly blinded. Even radar could be distracted by the background of solar interference, and Commodore Brennan had enlisted two large sunspots as minor allies.

  Within seconds, the rockets were lost in the glare. Minutes seemed to pass; then the sunlight abruptly multiplied itself a

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  hundredfold. The folks up on Earth, thought Wheeler as he readjusted the filters of his visor, will be having a grandstand view tonight. And the atmosphere which is such a nuisance to astronomers will protect them from anything that these war­heads can radiate.

  There was no way to tell if the missiles had done any damage. That enormous and soundless explosion might have dissipated itself harmlessly into space. This would be a strange battle, he realized. He might never even see the Federation ships, which would almost certainly be painted as black as night to make them undetectable.

  Then he saw that something was happening to the dome. It was no longer a gleaming spherical mirror reflecting only the single image of the sun. Light was splashing from it in all di­rections, and its brilliance was increasing second by second. From somewhere out in space, power was being poured into the fortress. That could only mean that the ships of the Federation were floating up there against the stars, beaming countless millions of kilowatts down upon the Moon. But there was still no sign of them, for there was nothing to reveal the track of the river of energy pouring invisibly through space.

  The dome was now far too bright to look upon directly, and Wheeler readjusted his filters. He wondered when it was going to reply to the attack, or indeed if it could do so while it was under this bombardment. Then he saw that the hemisphere was surrounded by a waveririg corona, like some kind of brush dis­charge. Almost at the same moment, Jamieson's voice rang in his ears.

  "Look, Con—right overhead!"

  He glanced away from the mirror and looked directly into the sky. For the first time, he saw one of the Federation ships. Though he did not know it, he was seeing the Acheron, the only spaceship ever to be built specifically for war. It was clearly visible, and seemed remarkably close. Between it and the for­tress, like an impalpable shield, flared a disk of light which as he watched turned cherry-red, then blue-white, then the deadly searing violet seen only in the hottest of the stars. The shield wavered back and forth, giving the impression of being balanced by tremendous and opposing energies. As Wheeler stared, ob-

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  livious to his peril, he saw that the whole ship was surrounded by a faint halo of light, brought to incandescence only where the weapons of the fortress tore against it.

  It was some time before he realized that there were two other ships in the sky, each shielded by its own flaming nimbus. Now the battle was beginning to take shape; each side had cautiously tested its defenses and its weapons, and only now had the real trial of strength begun.

  The two astronomers stared in wonder at the moving fireballs of the ships. Here was something totally new—something far more important than any mere weapon. These vessels possessed a means of propulsion which must make the rocket obsolete. They could hove
r motionless at will, then move off in any di­rection at a high acceleration. They needed this mobility; the fortress, with all its fixed equipment, far outpowered them and much of their defense lay in their speed.

  In utter silence, the battle was rising to its climax. Millions of years ago the molten rock had frozen to form the Sea of Rains, and now the weapons of the ships were turning it once more to lava. Out by the fortress, clouds of incandescent vapor were being blasted into the sky as the beams of the attackers spent their fury against the unprotected rocks. It was impossible to tell which side was inflicting the greater damage. Now and again a screen would flare up, as a 'flicker of heat passes over white-hot steel. When that happened to one of the battleships, it would move away with that incredible acceleration, and it would be several seconds before the focusing devices of the fort had located it again.