air pipes - both of them - were no longer connected to Selene. The purifier was pumping oxygen into the Sea through one pipe and, worse still, sucking in dust through the other. Lawrence wondered how long it would take to clean out the filters, but wasted no further time upon that thought. He was too busy calling Selene.
There was no answer. He tried all the cruiser's frequencies, without receiving even a whisper of a carrier wave. The Sea of Thirst was as silent to radio as it was to sound.
They're finished, he said to himself; it's all over. It was a near thing, but we just couldn't make it. And all we needed was another hour.
What could have happened? he thought dully. Perhaps the hull had collapsed under the weight of the dust. No - that was very unlikely; the internal air pressure would have prevented that. It must have been another subsidence. He was not sure, but he thought that there had been a slight tremor underfoot. From the beginning he had been aware of this danger, but could see no way of guarding against it. This was a gamble they had all taken, and Selene had lost.
Even as Selene started to fall, something told Pat that this was quite different from the first cave-in. It was much slower, and there were scrunching, squishing noises from outside the hull which, even in that desperate moment, struck Pat as being unlike any sounds that dust could possibly make.
Overhead, the oxygen pipes were tearing loose. They were not sliding out smoothly, for the cruiser was going down stern first, tilting toward the rear. With a crack of splintering Fiberglas, the pipe just ahead of the air-lock galley ripped through the roof and vanished from sight. Immediately, a thick jet of dust sprayed into the cabin, and fanned out in a choking cloud where it hit the floor.
Commodore Hansteen was nearest, and got there first. Tearing off his shirt, he swiftly wadded it into a ball and rammed it into the aperture. The dust spurted in all directions as he struggled to block the flow. He had almost succeeded when the forward pipe ripped loose-and the main lights went out as, for the second time, the cable conduit was wrenched away.
"I'll take it!" shouted Pat. A moment later, also shirtless, he was trying to stem the torrent pouring in through the hole.
He had sailed the Sea of Thirst a hundred times, yet never before had he touched its substance with his naked skin. The gray powder sprayed into his nose and eyes, half choking and wholly blinding him. Though it was as bone dry as the dust from a Pharaoh's tomb - dryer than this, indeed, for it was a million times older than the pyramids - it had a curiously soapy feeling. As he fought against it, Pat found himself thinking: If there is one death worse than being drowned, it's being buried alive.
When the jet weakened to a thin trickle, he knew that he had avoided that fate-for the moment. The pressure produced by fifteen meters of dust, under the low lunar gravity, was not difficult to overcome-though it would have been another story if the holes in the roof had been much larger.
Pat shook the dust from his head and shoulders, and cautiously opened his eyes. At least he could see again; thank heaven for the emergency lighting, dim though it was. The Commodore had already plugged his leak, and was now calmly sprinkling water from a paper cup to lay the dust. The technique was remarkably effective, and the few remaining clouds quickly collapsed into patches of mud.
Hansteen looked up and caught Pat's eye.
"Well, Captain," he said. "Any theories?"
There were times, thought Pat, when the Commodore's Olympian self-control was almost maddening. He would like to see him break, just once. No-that was not really true. His feeling was merely a flash of envy, even of jealousy - understandable, but quite unworthy of him. He should be ashamed of it, and he was.
"I don't know what's happened," he said. "Perhaps the people on top can tell us."
It was an uphill walk to the pilot's position, for the cruiser was now tilted at about thirty degrees from the horizontal. As Pat took his seat in front of the radio, he felt a kind of despairing numbness that surpassed anything he had known since their original entombment. It was a sense of resignation, an almost superstitious belief that the gods