They could have continued with the book readings, but somehow both _Shane_ and _The Orange and the Apple_ had lost their appeal. No one could concentrate on anything now except the prospects of rescue, and the renewal of life that lay before them when they had rejoined the human race.
From overhead, there was a sudden, heavy thump. That could mean only one thing; the grab had reached the bottom of the shaft, and the caisson was clear of dust. Now it could be coupled to one of the igloos and pumped full of air.
It took more than an hour to complete the connection and make all the necessary tests. The specially modified Mark XIX igloo, with a hole in its floor just large enough to accommodate the protruding end of the caisson, had to be positioned and inflated with the utmost care. The lives of _Selene’s_ passengers, and also those of the men attempting to rescue them, might depend upon this air seal.
Not until Chief Engineer Lawrence was thoroughly satisfied did he strip off his space suit and approach that yawning hole. He held a floodlight above the opening and looked down into the shaft, which seemed to dwindle away to infinity. Yet it was just seventeen meters to the bottom; even in this low gravity, an object would take only five seconds to fall that distance.
Lawrence turned to his assistants; each was wearing a space suit, but with the face plate open. If anything went wrong, those plates could be snapped shut in a fraction of a second, and the men inside would probably be safe. But for Lawrence there would be no hope at all–nor for the twenty-two aboard _Selene_.
“You know exactly what to do,” he said. “If I want to come up in a hurry, all of you pull on the rope ladder together. Any questions?”
There were none; everything had been thoroughly rehearsed. With a nod to his men and a chorus of “Good lucks” in return, Lawrence lowered himself into the shaft.
He let himself fall most of the way, checking his speed from time to time by grabbing at the ladder. On the Moon it was quite safe to do this; well, _almost_ safe. Lawrence had seen men killed because they had forgotten that even this gravity field could accelerate one to a lethal speed in less than ten seconds.
This was like Alice’s fall into Wonderland (so much of Carroll might have been inspired by space travel), but there was nothing to see on the way down except the blank concrete wall, so close that Lawrence had to squint to focus upon it. And then, with the slightest of bumps, he had reached the bottom.
He squatted down on the little metal platform, the size and shape of a manhole cover, and examined it carefully. The trapdoor valve that had been open during the piston’s descent through the dust was leaking very slightly, and a trickle of gray powder was creeping round the seal. It was nothing to worry about, but Lawrence could not help wondering what would happen if the valve opened under the pressure from beneath. How fast would the dust rise up the shaft, like water in a well? Not as fast, he was quite certain, as he could go up that ladder.
Beneath his feet now, only centimeters away, was the roof of the cruiser, sloping down into the dust at that maddening thirty degrees. His problem was to mate the horizontal end of the shaft with the sloping roof of the cruiser–and to do it so well that the coupling would be dust-tight.
He could see no flaw in the plan; nor did he expect to, for it had been devised by the best engineering brains on Earth and Moon. It even allowed for the possibility that _Selene_ might shift again, by a few centimeters, while he was working here. But theory was one thing–and, as he knew all too well, practice was another.
There were six large thumbscrews spaced around the circumference of the metal disc on which Lawrence was sitting, and he started to turn them one by one, like a drummer tuning his instrument. Connected to the lower side of the platform was a short piece of concertina-like tubing, almost as wide as the caisson, and now folded flat. It formed a flexible coupling large enough for a man to crawl through, and was now slowly opening as Lawrence turned the screws.
One side of the corrugated tube had to stretch through forty centimeters to reach the sloping roof; the other had to move scarcely at all. Lawrence’s chief worry had been that the resistance of the dust would prevent the concertina from opening, but the screws were easily overcoming the pressure.
Now none of them could be tightened any further; the lower end of the coupling must be flush against _Selene’s_ roof, and sealed to it, he hoped, by the rubber gasket around its rim. How tight that seal was, he would very soon know.
Automatically checking his escape route, Lawrence glanced up the shaft. He could see nothing past the glare of the floodlight hanging two meters above his head, but the rope ladder stretching past it was extremely reassuring.
“I’ve let down the connector,” he shouted to his invisible colleagues. “It seems to be flush against the roof. Now I’m going to open the valve.”
Any mistake now, and the whole shaft would be flooded, perhaps beyond possibility of further use. Slowly and gently, Lawrence released the trap door which had allowed the dust to pass through the piston while it was descending. There was no sudden upwelling; the corrugated tube beneath his feet was holding back the Sea.
Lawrence reached through the valve-and his fingers felt the roof of _Selene_, still invisible beneath the dust but now only a handsbreath away. Few achievements in all his life had ever given him such a sense of satisfaction. The job was still far from finished–_but he had reached the cruiser_. For a moment he crouched in his little pit, feeling as some old-time miner must have when the first nugget of gold gleamed in the lamplight.
He banged three times on the roof. Immediately, his signal was returned. There was no point in striking up a Morse conversation, for, if he wished, he could talk directly through the microphone circuit, but he knew the psychological effect that his tapping would have. It would prove to the men and women in _Selene_ that rescue was now only centimeters away.
Yet there were still major obstacles to be demolished, and the next one was the manhole cover on which he was sitting– the face of the piston itself. It had served its purpose, holding back the dust while the caisson was being emptied, but now it had to be removed before anyone could escape from Selene. This had to be done, however, without disturbing the flexible coupling that it had helped to place in position.
To make this possible, the circular face of the piston had been built so that it could be lifted out, like a saucepan lid, when eight large bolts were unscrewed. It took Lawrence only a few minutes to deal with these and to attach a rope to the new loose metal disc; then he shouted, “Haul away!”
A fatter man would have had to climb the shaft while the circular lid came up after him, but Lawrence was able to squeeze against the wall while the metal plate, moving edgeways, was hoisted past him There goes the last line of dofense, he told himself, as the disc vanished overhead. Now it would be impossible to seal the shaft again if the coupling failed and the dust started to pour in.
“Bucket!” he shouted. It was already on its way down.
Forty years ago, thought Lawrence, I was playing on a California beach with bucket and spade, making castles in the sand. Now here I am on the Moon–Chief Engineer, Earthside, no less–shoveling in even deadlier earnest, with the whole human race looking over my shoulder.
When the first load was hoisted up, he had exposed a considerable area of _Selene’s_ roof. The volume of dust trapped inside the coupling-tube was quite small, and two more bucketfuls disposed of it.
Before him now was the aluminized fabric of the sun shield, which had long ago crumpled under the pressure. Lawrence cut it away without difficulty–it was so fragile that he could tear it with his bare hands–and exposed the slightly roughened Fiberglas of the outer hull. To cut through that with a small power saw would be easy; it would also be fatal.
For by this time _Selene’s_ double hull had lost its integrity; when the roof had been damaged, the dust would have flooded into the space between the two walls. It would be waiting there, under pressure, to come spurting out as soon as he made his first incision. Before he could enter _Selene_, that thin but deadly layer of dust would have to be immobilized.