A Fall of Moondust

It was time to turn back, to sail down the canyon into the open sea. Pat aimed the blunt prow of Selene toward the narrow rift in the mountains, and the high walls enfolded them again. On the outward journey he left the lights on, so that the passengers could see where they were going; besides, that trick of the Night Ride would not work so well a second time.

Far ahead, beyond the reach of Selene's own illumination, a light was growing, spreading softly across the rocks and crags. Even in her last quarter, Earth still had the power of a dozen full moons, and now that they were emerging from the shadow of the mountains, she was once more the mistress of the skies. Every one of the twenty-two men and women aboard Selene looked up at that blue-green crescent, admiring its beauty, wondering at its brilliance. How strange that the familiar fields and lakes and forests of Earth shone with such celestial glory when one looked at them from afar! Perhaps there was a lesson here; perhaps no man could appreciate his own world until he had seen it from space.

And upon Earth, there must be many eyes turned toward the waxing Moon—more than ever before, now that the Moon meant so much to mankind. It was possible, but unlikely, that even now some of those eyes were peering through powerful telescopes at the faint spark of Selene's floodlights as it crept through the lunar night. But it would mean nothing to them when that spark flickered and died.

For a million years the bubble had been growing, like a vast abscess, below the root of the mountains. Throughout the entire history of Man, gas from the Moon's not yet wholly dead interior had been forcing itself along lines of weakness, accumulating in cavities hundreds of meters below the surface. On nearby Earth, the ice ages had marched past, one by one, while the buried caverns grew and merged and at last coalesced. Now the abscess was about to burst.

Captain Harris had left the controls on autopilot and was talking to the front row of passengers when the first tremor shook the boat. For a fraction of a second he wondered if a fan blade had hit some submerged obstacle; then, quite literally, the bottom fell out of his world.

It fell slowly, as all things must upon the Moon. Ahead of Selene, in a circle many acres in extent, the smooth plain puckered like a navel. The Sea was alive and moving, stirred by the forces that had waked it from its age-long sleep. The center of the disturbance deepened into a funnel, as if a giant whirlpool were forming in the dust. Every stage of that nightmare transformation was pitilessly illuminated by the earthlight, until the crater was so deep that its far wall was completely lost in shadow, and it seemed as if Selene were racing into a curving crescent of utter blackness—an arc of annihilation.

The truth was almost as bad. By the time that Pat had reached the controls, the boat was sliding and skittering far down that impossible slope. Its own momentum and the accelerating flow of the dust beneath it were carrying it headlong into the depths. There was nothing he could do but attempt to keep on an even keel, and to hope that their speed would carry them up the far side of the crater before it collapsed upon them.

If the passengers screamed or cried out, Pat never heard them. He was conscious only of that dreadful, sickening slide, and of his own attempts to keep the cruiser from capsizing. Yet even as he fought with the controls, feeding power first to one fan, then to the other, in an effort to straighten Selene's course, a strange, nagging memory was teasing his mind. Somewhere, somehow, he had seen this happen before.

That was ridiculous, of course, but the memory would not leave him. Not until he reached the bottom of the funnel and saw the endless slope of dust rolling down from the crater's star-fringed lip did the veil of time lift for a moment.

He was a boy again, playing in the hot sand of a forgotten summer. He had found a tiny pit, perfectly smooth and symmetrical, and there was something lurking in its depths—something completely buried except for its waiting jaws. The boy had watched, wondering, already conscious of the fact that this was the stage for some microscopic drama. He had seen an ant, mindlessly intent upon its mission, stumble at the edge of the crater and topple down the slope.

It would have escaped easily enough—but when the first grain of sand had rolled to the bottom of the pit, the waiting ogre had reared out of its lair. With its forelegs, it had hurled a fusillade of sand at the struggling insect, until the avalanche had overwhelmed it and brought it sliding down into the throat of the crater.