But perhaps they had been; perhaps it was the real Pat Harris, the real Sue Wilkins, that had finally emerged from disguise, revealed by the strain and anxiety of the past few days. He wondered how he could be sure of this, but even as he did so, he knew that only time could give the answer. If there was a clear-cut, scientific test that could tell you when you were in love, Pat had not yet come across it.
The dust that lapped if that was the word against the quay from which Selene had departed four days ago was only a couple of meters deep, but for this test no greater depth was needed. If the hastily built equipment worked here, it would work out in the open Sea.
Lawrence watched from the Embarkation Building as his space-suited assistants bolted the framework together. It was made, like ninety per cent of the structures on the Moon, from slotted aluminum strips and bars. In some ways, thought Lawrence, the Moon was an engineer's paradise. The low gravity, the total absence of rust or corrosion indeed, of weather itself, with its unpredictable winds and rains and frosts-removed at once a whole range of problems that plagued all terrestrial enterprises. But to make up for that, of course, the Moon had a few specialities of its own like the two-hundred-below-zero nights, and the dust that they were fighting now.
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.
So did I at first. But I know these symptoms especially the quick breathing. We're running into carbon-dioxide poisoning.
But that's ridiculous. We should be all right for another three days unless something has gone wrong with the air purifiers.
I'm afraid it has. What system do we use to get rid of the carbon dioxide?
Straight chemical absorption. It's a very simple, reliable setup; we've never had any trouble with it before.
Yes, but it's never had to work under these conditions before. I think the heat may have knocked out the chemicals. Is there any way we can check them?
Pat shook his head.
No. The access hatch is on the outside of the hull.
Sue, my dear, said a tired voice which they hardly recognized as belonging to Mrs. Schuster, do you have anything to fix a headache?
If you do, said another passenger, I'd like some as well.
Pat and the Commodore looked at each other gravely. The classic symptoms were developing with textbook precision.
How long would you guess? said Pat quietly.
Two or three hours at the most. And it will be at least six before Lawrence and his men can get here.