“This is Chief Engineer Lawrence speaking. Can you hear me?”
Pat cupped his hands over the opening, and answered slowly: “Hearing you loud and clear. How do you receive us?”
“Very clear. Are you all right?”
“Yes—what’s happened?”
“You’ve dropped a couple of meters—no more than that. We hardly noticed anything up here, until the pipes came adrift. How’s your air?”
“Still good—but the sooner you start supplying us, the better.”
“Don’t worry, we’ll be pumping again as soon as we get the dust out of the filters, and can rush out another drill head from Port Roris. The one you’ve just unscrewed was the only spare; it was lucky we had that.”
So it will be at least an hour, Pat told himself, before their air supply could be secured again. That, however, was not the problem that now worried him. He knew how Lawrence had hoped to reach them, and he realized that the plan would not work now that Selene was no longer on an even keel.
“How are you going to get at us?” he asked bluntly.
There was only the briefest of hesitations before Lawrence answered.
“I’ve not worked out the details, but we’ll add another sec tion to the caisson and continue it down until it reaches you. Then we’ll start scooping out the dust until we get to the bottom. That will take us to within a few centimeters of you; we’ll cross that gap somehow. But there’s one thing I want you to do first.”
“What’s that?”
“I’m ninety per cent sure that you won’t settle again—but if you’re going to, I’d rather you did it now. I want you all to jump up and down together for a couple of minutes.”
“Will that be safe?” asked Pat doubtfully. “Suppose this pipe tears out again?”
“Then you can plug it again. Another small hole won’t matter—but another subsidence will, if it happens when we’re trying to make a man-sized opening in the roof.”
Selene had seen some strange sights, but this was undoubtedly the strangest. Twenty-two men and women were solemnly jumping up and down in unison, rising to the ceiling and then pushing themselves back as vigorously as possible to the floor. All the while Pat kept a careful watch on that pipe leading to the upper world; after a minute’s strenuous exertion on the part of her passengers, Selene had moved downward by less than two centimeters.
He reported this to Lawrence, who received the news with thankfulness. Now that he was reasonably sure that Selene would not shift again, he was confident that he could get these people out. Exactly how, he was not yet certain, but the plan was beginning to form in his mind.
It took shape over the next twelve hours, in conferences with his brains trust and experiments on the Sea of Thirst. The Engineering Division had learned more about the dust in the last week than during the whole of its previous existence. It was no longer fighting in the dark against a largely unknown opponent. It understood which liberties could be taken, and which could not.
Despite the speed with which the changed plans were drawn up and the necessary hardware constructed, there was no undue haste and certainly no carelessness. For this was another operation that had to work the first time. If it failed, then at the very least the caisson would have to be abandoned and a new one sunk. And at the worst—those aboard Selene would be drowned in dust.
“It’s a pretty problem,” said Tom Lawson, who liked pretty problems—and not much else. “The lower end of the caisson’s wide open to the dust, because it’s resting against Selene at only one point, and the tilt of the roof prevents it from sealing. Before we can pump out the dust, we have to close that gap.
“Did I say ‘pump’? That was a mistake. You can’t pump the stuff; it has to be lifted. And if we tried that as things are now, it would flow in just as fast at the bottom of the tube as we took it out of the top.”
Tom paused and grinned sardonically at his multimillion audience, as if challenging it to solve the problem he had outlined. He let his viewers stew in their own thoughts for a while, then picked up the model lying on the studio table. Though it was an extremely simple one, he was rather proud of it, for he had made it himself. No one could have guessed, from the other side of the camera, that it was only cardboard sprayed with aluminum paint.
“This tube,” he said, “represents a short section of the caisson that’s now leading down to _Selene_--and which, as I said, is full of dust. Now _this_--“ with his other hand, he picked up a stubby cylinder, closed at one end—“fits snugly inside the caisson, like a piston. It’s very heavy, and will try to sink under its own weight. But it can’t do so, of course, while the dust is trapped underneath it.”
Tom turned the piston until its flat end was toward the camera. He pressed his forefinger against the center of the circular face, and a small trap door opened.
“This acts as a valve. When it’s open, dust can flow through and the piston can sink down the shaft. As soon as it reaches the bottom, the valve will be closed by a signal from above. That will seal off the caisson, and we can start scooping out the dust.
“It sounds very simple, doesn’t it? Well, it’s not. There are about fifty problems I haven’t mentioned. For example, as the caisson is emptied, it will try to float up to the surface with a lift of a good many tons. Chief Engineer Lawrence has worked out an ingenious system of anchors to hold it down.
“You’ll realize, of course, that even when this tube has been emptied of dust, there will still be that wedge-shaped gap between its lower end and Selene’s roof. How Mister Lawrence proposes to deal with that, I don’t know. And please don’t send me any more suggestions; we’ve already had enough half-baked ideas on this program to last a lifetime.
“This-piston gadget—isn’t just theory. The engineers here have built and tested it during the last twelve hours, and it’s now in action. If I can make any sense of the signals the man’s waving at me, I think we’re now going over to the Sea of Thirst, to find out what’s happening on the raft.”
The temporary studio in the Hotel Roris faded from a million screens; in its place was the picture that, by this time, must have been familiar to most of the human race.
There were now three igloos of assorted sizes on or around the raft; as the sunlight glinted from their reflecting outer surfaces, they looked like giant drops of mercury. One of the dustskis was parked beside the largest dome; the other two were in transit, still shuttling supplies from Port Roris.
Like the mouth of a well, the caisson projected from the Sea. Its rim was only twenty centimeters above the dust, and the opening seemed much too narrow for a man to enter. It would, indeed, have been a very tight fit for anyone wearing a space suit—but the crucial part of this operation would be done without suits.
At regular intervals, a cylindrical grab was disappearing into the well, to be hauled back to the surface a few seconds later by a small but powerful crane. On each withdrawal, the grab would be swung clear of the opening, and would disgorge its contents back into the Sea. For an instant a gray dunce’s cap of dust would stand in momentary balance on the level plain; then it would collapse in slow motion, vanishing completely before the next load had emerged from the shaft. It was a conjuring trick being carried out in broad daylight, and it was fascinating to watch. More effectively than a thousand words of description, it told the viewers all that they needed to know about the Sea of Thirst.
The grab was taking longer on its journeys now, as it plunged deeper into the dust. And at last there came the moment when it emerged only half full, and the way to Selene was open—except for that roadblock at the end.
CHAPTER TWENTY NINE
“We’re still in very good spirits,” said Pat, into the microphone that had now been lowered down the air shaft. “Of course, we had a bad shock after that second cave-in, when we lost contact with you—but now we’re sure you’ll soon have us out. We can hear the grab at work, as it scoops up the dust, and it’s wonderful to know that help is so close. We’ll
never forget,” he added, a little awkwardly, “the efforts that so many people have made to help us, and whatever happens we’d like to thank them. All of us are quite sure that everything possible has been done.
“And now I’ll hand over the mike, since several of us have messages we want to send. With any luck at all, this will be the last broadcast from Selene.”
As he gave the microphone to Mrs. Williams, he realized that he might have phrased that last remark a little better; it could be interpreted in two ways. But now that rescue was so close at hand, he refused to admit the possibility of further setbacks. They had been through so much that, surely, nothing more would happen to them now.
Yet he knew that the final stage of the operation would be the most difficult, and the most critical, of all. They had discussed it endlessly during the last few hours, ever since Chief Engineer Lawrence had explained his plans to them. There was little else to talk about now that, by common consent, the subject of flying saucers was vetoed.
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 Califo
rnia 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.
Lawrence rapped briskly against the roof; as he had expected, the sound was muffled by the dust. What he did not expect was to receive an urgent, frantic tattoo in reply.
This, he could tell at once, was no reassuring “I’m O.K.” signal from inside the cruiser. Even before the men overhead could relay the news to him, Lawrence had guessed that the Sea of Thirst was making one final bid to keep its prey.
Because Karl Johanson was a nucleonics engineer, had a sensitive nose, and happened to be sitting at the rear of the bus, he was the one who spotted the approach of disaster. He remained quite still for a few seconds, nostrils twitching, then said “Excuse me” to his companion in the aisle seat, and strolled quietly to the washroom. He did not wish to cause alarm if there was no need, especially when rescue seemed so near. But in his professional lifetime he had learned, through more examples than he cared to remember, never to ignore the smell of burning insulation.
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