Arthur Clarke - Earthlight

And then, as he stared into the east, he saw a line of dust rising from the plain, sweeping toward him as if driven by a mighty wind. The concussion was racing through the rock, hurling the surface dust high into the sky as it passed. The swift, inexorable approach of that silently moving wall, advancing at the rate of several kilometers a second, was enough to strike terror into anyone who did not know its cause. But it was quite harmless; when the wave-front reached him, it was as if a minor earthquake had passed. The veil of dust reduced visibility to Zero for a few seconds, then subsided as swiftly as it had come.

When Wheeler looked again for the remaining ships, they were so far away that their screens had shrunk to little balls of fire against the zenith. At first he thought they were retreating; then, abruptly, the screens began to expand as they came down into the attack under a terrific vertical acceleration. Over by the fortress the lava, like some tortured living creature, was throwing itself madly into the sky as the beams tore into it.

The Acheron and Eridanus came out of their dives about a kilometer above the fort. For an instant, they were motionless; then they went back into the sky together. But the Eridanus had been mortally wounded, though Wheeler knew only that one of the screens was shrinking much more slowly than the other. With a feeling of helpless fascination, he watched the stricken ship fall back toward the Moon. He wondered if the fort would use its enigmatic weapon again, or whether the defenders realized that it was unnecessary.

About ten kilometers up, the screens of the Eridmus seemed to explode and she hung unprotected, a blunt torpedo of black metal, almost invisible against the sky. Instantly her light-absorbing paint, and the armor beneath, were torn off by the beams of the fortress. The great ship turned cherry-red, then white. She swung over so that her prow turned toward the Moon, and began her last dive. At first it seemed to Wheeler that she was heading straight toward him; then he saw that she was aimed at the fort. She was obeying her captain’s last command.

It was almost a direct hit. The dying ship smashed into the lake of lava and exploded instantly, engulfing the fortress in an expanding hemisphere of flame. This, thought Wheeler, must surely be the end. He waited for the shock wave to reach him, and again watched the wall of dust sweep by—this time into the north. The concussion was so violent that it jerked him off his feet, and he did not see how anyone in the fort could have survived. Cautiously, he put down the mirror which had given him almost all his view of the battle, and peered over the edge of his trench. He did not know that the final paroxysm was yet to come.

Incredibly, the dome was still there, though now it seemed that part of it had been sheared away. And it was inert and lifeless : its screens were down, its energies exhausted, its garrison, surely, already dead. If so, they had done their work. Of the remaining Federal ship, there was no sign. She was already retreating toward Mars, her main armament completely useless and her drive units on the point of failure. She would never fight again, yet in the few hours of life that were left to her, she had one more role to play.

“It’s all over, Sid,” Wheeler called into his suit radio. “It’s safe to come and look now.”

Jamieson climbed up out of a crack fifty meters away, holding the radiation detector in front of him.

“It’s still hot around here,” Wheeler heard him grumble, half to himself. “The sooner we get moving the better.”

“Will it be safe to go back to Ferdinand and put through a radio—” began Wheeler. Then he stopped. Something was happening over by the dome.

In a blast like an erupting volcano, the ground tore apart. An enormous geyser began to soar into the sky, hurling great boulders thousands of meters toward the stars. It climbed swiftly above the plain, driving a thunderhead of smoke and spray before it. For a moment it towered against the southern sky, like some incredible, heaven-aspiring tree that had sprung from the barren soil of the Moon. Then, almost as swiftly as it had grown, it subsided in silent ruin and its angry vapors dispersed into space.

The thousands of tons of heavy liquid holding open the deepest shaft that man had ever bored had finally come to the boiling point, as the energies of the battle seeped into the rock. The mine had blown its top as spectacularly as any oil well on Earth, and had proved that an excellent explosion could still be arranged without the aid of atom bombs.

To the Observatory, the battle was no more than an occasional distant earthquake, a faint vibration of the ground which disturbed some of the more delicate instruments but did no material damage. The psychological damage, however, was a different matter. Nothing is so demoralizing as to know that great and shattering events are taking place, but to be totally unaware of their outcome. The Observatory was full of wild rumors, the Signals Office besieged with inquiries. But even here there was no information. All news broadcasts from Earth had ceased; the whole world was waiting, as if with bated breath, for the fury of the battle to die away so that the victor could be known. That there would be no victor was the one thing that had not been anticipated.

Not until long after the last vibrations had died away and the radio had announced that the Federation forces were in full retreat did Maclaurin permit anyone to go up to the surface. The report that came down was, after the strain and excitement of the last few hours, not only a relief but a considerable anticlimax. There was a small amount of increased radioactivity about, but not the slightest trace of damage. What it would be like on the other side of the mountains was, of course, a different matter.

The news that Wheeler and Jamieson were safe gave a tremendous boost to the staff’s morale. Owing to a partial breakdown of communications, it had taken them almost an hour to contact Earth and to get connected to the Observatory. The delay had been both infuriating and worrying, for it had left them wondering if the Observatory had been destroyed. They dared not set out on foot until they were sure they had somewhere to go—and Ferdinand was now too radioactive to be a safe refuge.

Sadler was in Communications trying to find out what was happening, when the message came through. Jamieson, sounding very tired, gave a brief report of the battle and asked for instructions.

“What’s the radiation reading inside the cab?” Maclaurin asked. Jamieson called back the figures: it still seemed strange to Sadler that the message should have to go all the way to Earth just to span a hundred kilometers of the Moon, and he was never able to get used to the three-second delay that this implied.

“I’ll get the health section to work out the tolerance,” Maclaurin answered. “You say it’s only a quarter of that reading out in the open?”

“Yes—we’ve stayed outside the tractor as much as possible, and have come in every ten minutes to try and contact you.”

“The best plan is this—we’ll send a Caterpillar right away, and you start walking toward us. Any particular rendezvous you’d like to aim for?”

Jamieson thought for a moment.

“Tell your driver to head for the five-kilometer marker on this side of Prospect; we’ll reach it about the same time as he does. We’ll keep our suit radios on so there’ll be no chance of him missing us.”

As Maclaurin was giving his orders, Sadler asked if there was room for an extra passenger in the rescue tractor. It would give him a chance of questioning Wheeler and Jamieson much sooner than would otherwise be the case. When they reached the Observatory—though they did not know it yet—they would be whipped into hospital at once and treated for radiation sickness.