A Fall of Moondust

The light framework of the raft rested upon a dozen large metal drums, which carried the prominently stenciled words: “Contents Ethyl Alcohol. Please return when empty to No. 3 Dispatching Center, Copernicus.” Their contents now were a very high grade of vacuum; each drum could support a weight of two lunar tons before sinking.

Now the raft was rapidly taking shape. Be sure to have plenty of spare nuts and bolts, Lawrence told himself. He had seen at least six dropped in the dust, which had instantly swallowed them. And there went a wrench. Make an order that all tools must be tied to the raft even when in use, however inconvenient that might be.

Fifteen minutes—not bad, considering that the men were working in vacuum and therefore were hampered by their suits. The raft could be extended in any direction as required, but this would be enough to start with. This first section alone could carry over twenty tons, and it would be some time before they unloaded that weight of equipment on the site.

Satisfied with this stage of the project, Lawrence left the Embarkation Building while his assistants were still dismantling the raft. Five minutes later (that was one advantage of Port Roris—you could get anywhere in five minutes), he was in the local engineering depot. What he found there was not quite so satisfactory.

Supported on a couple of trestles was a two-meter-square mock-up of Selene's roof—an exact copy of the real thing, made from the same materials. Only the outer sheet of aluminized fabric that served as a sun shield was missing; it was so thin and flimsy that it would not affect the test.

The experiment was an absurdly simple one, involving only three ingredients: a pointed crowbar, a sledge hammer, and a frustrated engineer, who, despite strenuous efforts, had not yet succeeded in hammering the bar through the roof.

Anyone with a little knowledge of lunar conditions would have guessed at once why he had failed. The hammer, obviously, had only a sixth of its terrestrial weight; therefore-equally obviously—it was that much less effective.

The reasoning would have been completely false. One of the hardest things for the layman to understand was the difference between weight and mass, and the inability to do so had led to countless accidents. For weight was an arbitrary characteristic; you could change it by moving from one world to another. On Earth, that hammer would weigh six times as much as it did here; on the sun, it would be almost two hundred times heavier; and in space it would weigh nothing at all.

But in all three places, and indeed throughout the Universe, its mass or inertia would be exactly the same. The effort needed to set it moving at a certain speed, and the impact it would produce when stopped, would be constant through all space and time. On a nearly gravityless asteroid, where it weighed less than a feather, that hammer would pulverize a rock just as effectively as on Earth.

“What's the trouble?” said Lawrence .

“The roof's too springy,” explained the engineer, rubbing the sweat from his brow. “The crowbar just bounces back every time it's hit.”

“I see. But will that happen when we're using a fifteen-meter pipe, with dust packed all around it? That may absorb the recoil.”

“Perhaps—but look at this.”

They kneeled beneath the mock-up and inspected the underside of the roof. Chalk lines had been drawn upon it to indicate the position of the electric wiring, which had to be avoided at all costs.

“This Fiberglas is so tough, you can't make a clean hole through it. When it does yield, it splinters and tears. See-it's already begun to star. I'm afraid that if we try this bruteforce approach, we'll crack the roof.”

“And we can't risk that,” Lawrence agreed. “Well, drop the idea. If we can't pile drive, we'll have to bore. Use a drill, screwed on the end of the pipe so it can be detached easily. How are you getting on with the rest of the plumbing?”

“Almost ready—it's all standard equipment. We should be finished in two or three hours.”

“I'll be back in two,” said Lawrence . He did not add, as some men would have done, “I want it finished by then.” His staff was doing its utmost, and one could neither bully nor cajole trained and devoted men into working faster than their maximum. Jobs like this could not be rushed, and the deadline for Selene's oxygen supply was still three days away. In a few hours, if all went well, it would have been pushed into the indefinite future.

Unfortunately, all was going very far from well.

Commodore Hansteen was the first to recognize the slow, insidious danger that was creeping up upon them. He had met it once before, when he had been wearing a faulty space suit on Ganymede-an incident he had no wish to recall, but had never really forgotten.

“Pat,” he said quietly, making sure that no one could overhear. “Have you noticed any difficulty in breathing?”

Pat looked startled, then answered, “Yes, now that you mention it. I'd put it down to the heat.”