A Fall of Moondust

CHAPTER 29

“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 defense, 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.

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.

He was in the washroom for less than fifteen seconds. When he emerged he was walking quickly, but not quickly enough to cause panic. He went straight to Pat Harris, who was deep in conversation with Commodore Hansteen, and interrupted them without ceremony.

“Captain”, he said in a low, urgent voice, “we're on fire. Go and check in the toilet. I've not told anyone else.”

In a second, Pat was gone, and Hansteen with him. In space, as on the sea, no one stopped to argue when he heard the word “Fire.” And Johanson was not the sort of man to raise a false alarm; like Pat, he was a Lunar Administration tech, and had been one of those whom the Commodore had selected for his riot squad.

The toilet was typical of that on any small vehicle of land, sea, air, or space; one could touch every wall without changing position. But the rear wall, immediately above the washbowl, could no longer be touched at all. The Fiberglas was blistered with heat, and was buckling and bulging even while the horrified spectators looked at it.

“My God!” said the Commodore. “That will be through in a minute. What's causing it?”

But Pat had already gone. He was back a few seconds later, carrying the cabin's two small fire extinguishers under his arms.

“Commodore”, he said, “go and report to the raft. Tell them we may only have a few minutes. I'll stay here in case it breaks through.”

Hansteen did as he was told. A moment later Pat heard his voice calling the message into the microphone, and the sudden turmoil among the passengers that followed. Almost immediately the door opened again, and he was joined by McKenzie.

“Can I help?” asked the scientist.

“I don't think so”, Pat answered, holding the extinguisher at the ready. He felt a curious numbness, as if this was not really happening to him, but was all a dream from which he would soon awaken. Perhaps by now he had passed beyond fear; having surmounted one crisis after another, all emotion had been wrung out of him. He could still endure, but he could no longer react.

“What's causing it?” asked McKenzie, echoing the Commodore's unanswered question and immediately following it with another. “What's behind this bulkhead?”

“Our main power supply. Twenty heavy-duty cells.”

“How much energy in them?”

“Well, we started with five thousand kilowatt-hours. We probably still have half of it.”

“There's your answer. Something's shorting out our power supply. It's probably been burning up ever since the overhead wiring got ripped out.”

The explanation made sense, if only because there was no other source of energy aboard the cruiser. She was completely fireproof, so could not support an ordinary combustion. But there was enough electrical energy in her power cells to drive her at full speed for hours on end, and if this dissipated itself in raw heat the results would be catastrophic.

Yet this was impossible; such an overload would have tripped the circuit breakers at once — unless, for some reason, they had jammed.

They had not, as McKenzie reported after a quick check in the air lock.

“All the breakers have jumped”, he said. “The circuits are as dead as mutton. I don't understand it.”

Even in this moment of peril, Pat could hardly refrain from smiling. McKenzie was the eternal scientist; he might be about to die, but he would insist on knowing how. If he was being burned at the stake — and a similar fate might well be in store — he would ask his executioners, “What kind of wood are you using?”

The folding door creased inward as Hansteen came back to report.

“Lawrence says he'll be through in ten minutes”, he said. “Will that wall hold until then?”

“God knows”, answered Pat. “It may last for another hour — it may go in the next five seconds. Depends how the fire's spreading.”

“Aren't there automatic fire-fighting appliances in that cornpartment?”

“There's no point in having them — this is our pressure bulkhead, and there's normally vacuum on the other side. That's the best fire fighter you can get.”

“That's it!” exclaimed McKenzie. “Don't you see? The whole compartment's flooded. When the roof tore, the dust started to work its way in. It's shorting all the electrical equipment.”

Pat knew, without further discussion, that McKenzie was right. By now all the sections normally open to space must be packed with dust. It would have poured in through the broken roof, flowed along the gap between the double hull, slowly accumulated around the open bus bars in the power compartment. And then the pyrotechnics would have started: there was enough meteoric iron in the dust to make it a good conductor. It would be arcing and shorting in there like a thousand electric fires.

“If we sprinkled water on that wall”, said the Commodore, “would it help matters — or would it crack the Fiberglas?”

“I think we should try it”, answered McKenzie, “but very carefully — not too much at a time.” He filled a plastic cup — the water was already hot — and looked enquiringly at the others. Since there were no objections, he began to splash a few drops on the slowly blistering surface.

The cracklings and poppings that resulted were so terrifying that he stopped at once. It was too big a risk; with a metal wall, it would have been a good idea, but this nonconducting plastic would shatter under the thermal stresses.

“There's nothing we can do in here”, said the Commodore. “Even those extinguishers won't help much. We'd better get out and block off this whole compartment. The door will act as a fire wall, and give us some extra time.”

Pat hesitated. The heat was already almost unbearable, but it seemed cowardice to leave. Yet Hansteen's suggestion made excellent sense; if he stayed here until the fire broke through, he would probably be gassed at once by the fumes.

“Right — let's get out”, he agreed. “We'll see what kind of barricade we can build behind this door.”

He did not think they would have much time to do it; already he could hear, quite distinctly, a frying, blistering sound from the wall that was holding the inferno at bay.