A Fall of Moondust

by Arthur C. Clarke

  “Receiving you,” said the Chief Engineer in a tired voice. “See if you can find some trace of them. I’ll send Duster One in to help. Are you sure there’s no chance of digging them out?”

  “It might take weeks, even if we could locate them. I saw one slide three hundred meters long. If you tried to dig, the rock would probably start moving again.”

  “Be very careful. Report every fifteen minutes, whether you find anything or not.”

  Lawrence turned away from the microphone, physically and mentally exhausted. There was nothing more that he could do—or, he suspected, that anyone could do. Trying to compose his thoughts, he walked over to the southward-facing observation window, and stared into the face of the crescent Earth.

  It was hard to believe that she was fixed there in the southern sky, that though she hung so close to the horizon, she would neither rise nor set in a million years. However long one lived here, one never really accepted this fact, which violated all the racial wisdom of mankind.

  On the other side of that gulf (already so small to a generation that had never known the time when it could not be crossed), ripples of shock and grief would soon be spreading. Thousands of men and women were involved, directly or indirectly, because the Moon had stirred briefly in her sleep.

  Lost in his thoughts, it was some time before Lawrence realized that the Port signals officer was trying to attract his attention.

  “Excuse me, sir—you’ve not called Duster One. Shall I do it now?”

  “What? Oh yes—go ahead. Send him to help Two in Crater Lake. Tell him we’ve called off the search in the Sea of Thirst.”

  CHAPTER SIX

  The news that the search had been called off reached Lagrange II when Tom Lawson, red-eyed from lack of sleep, had almost completed the modifications to the hundred-centimeter telescope. He had been racing against time, and now it seemed that all his efforts had been wasted. Selene was not in the Sea of Thirst at all, but in a place where he could never have found her—hidden from him by the ramparts of Crater Lake, and, for good measure, buried by a few thousand tons of rock.

  Tom’s first reaction was not one of sympathy for the victims, but of anger at his wasted time and effort. Those YOUNG ASTRONOMER FINDS MISSING TOURISTS headlines would never flash across the news-screens of the inhabited worlds. As his private dreams of glory collapsed, he cursed for a good thirty seconds, with a fluency that would have astonished his colleagues. Then, still furious, he started to dismantle the equipment he had begged, borrowed, and stolen from the other projects on the satellite.

  It would have worked; he was sure of that. The theory had been quite sound—indeed, it was based on almost a hundred years of practice. Infrared reconnaissance dated back to at least as early as World War II, when it was used to locate camouflaged factories by their telltale heat.

  Though Selene had left no visible track across the Sea, she must, surely, have left an infrared one. Her fans had stirred up the relatively warm dust a foot or so down, scattering it across the far colder surface layers. An eye that could see by the rays of heat could track her path for hours after she had passed. There would have been just time, Tom calculated, to make such an infrared survey before the sun rose and obliterated all traces of the faint heat trail through the cold lunar night.

  But, obviously, there was no point in trying now.

  It was well that no one aboard Selene could have guessed that the search in the Sea of Thirst had been abandoned, and that the dust-skis were concentrating their efforts inside Crater Lake. And it was well, also, that none of the passengers knew of Dr. McKenzie’s predictions.

  The physicist had drawn, on a piece of homemade graph paper, the expected rise of temperature. Every hour he noted the reading of the cabin thermometer and pinpointed it on the curve. The agreement with theory was depressingly good; in twenty hours, one hundred ten degrees Fahrenheit would be passed, and the first deaths from heatstroke would be occurring. Whatever way he looked at it, they had barely a day to live. In these circumstances, Commodore Hansteen’s efforts to maintain morale seemed no more than an ironic jest. Whether he failed or succeeded, it would be all the same by the day after tomorrow.

  Yet was that true? Though their only choice might lie between dying like men and dying like animals, surely the first was better. It made no difference even if Selene remained undiscovered until the end of time, so that no one ever knew how her occupants passed their final hours. This was beyond logic or reason; but so, for that matter, was almost everything that was really important in the shaping of men’s lives and deaths.

  Commodore Hansteen was well aware of that, as he planned the program for the dwindling hours that lay ahead. Some men are born to be leaders, and he was one of them. The emptiness of his retirement had been suddenly filled; for the first time since he had left the bridge of his flagship Centaurus, he felt whole again.

  As long as his little crew was busy, he need not worry about morale. It did not matter what they were doing, provided they thought it interesting or important. That poker game, for instance, took care of the Space Administration accountant, the retired civil engineer, and the two executives on vacation from New York. One could tell at a glance that they were all poker fanatics; the problem would be to stop them playing, not to keep them occupied.

  Most of the other passengers had split up into little discussion groups, talking quite cheerfully among themselves. The Entertainment Committee was still in session, with Professor Jayawardene making occasional notes while Mrs. Schuster reminisced about her days in burlesque, despite the attempts of her husband to shut her up. The only person who seemed a little apart from it all was Miss Morley, who was writing slowly and carefully, using a very minute hand, in what was left of her notebook. Presumably, like a good journalist, she was keeping a diary of their adventure. Commodore Hansteen was afraid that it would be briefer than she suspected, and that not even those few pages would be filled. And if they were, he doubted that anyone would ever read them.

  He glanced at his watch, and was surprised to see how late it was. By now, he should have been on the other side of the Moon, back in Clavius City. He had a lunch engagement at the Lunar Hilton, and after that a trip to—but there was no point in thinking about a future that could never exist. The brief present was all that would ever concern him now.

  It would be as well to get some sleep, before the temperature became unbearable. Selene had never been designed as a dormitory—or a tomb, for that matter—but it would have to be turned into one now. This involved some research and planning, and a certain amount of damage to Tourist Commission property. It took him twenty minutes to ascertain all the facts; then, after a brief conference with Captain Harris, he called for attention.

  “Ladies and gentlemen,” he said, “we’ve all had a busy day, and I think most of us will be glad to get some sleep. This presents a few problems, but I’ve been doing some experimenting and have discovered that with a little encouragement the center annrests between the seats come out. They’re not supposed to, but I doubt if the Commission will sue us. That means that ten of us can stretch out across the seats; the rest will have to use the floor.

  “Another point. As you will have noticed, it’s become rather warm, and will continue to do so for some time. Therefore I advise you to take off all unnecessary clothing; comfort is much more important than modesty.” (And survival, he added silently, is much more important than comfort—but it would be some hours yet before it came to that.)

  “We’ll turn off the main cabin lights, but since we don’t want to be in complete darkness, we’ll leave on the emergency lighting at low power. One of us will remain on watch at all times in the skipper’s seat. Mr. Harris is working out a roster of two-hour shifts. Any questions or comments?”

  There were none, and the Commodore breathed a sigh of relief. He was afraid that someone would be inquisitive about the rising temperature, and was not quite sure how he would have answered. His many accomplishments did not
include the gift of lying, and he was anxious that the passengers should have as untroubled a sleep as was possible in the circumstances. Barring a miracle, it would be their last.

  Miss Wilkins, who was beginning to lose a little of her professional smartness, took round final drinks for those who needed them. Most of the passengers had already begun to remove their outer clothing; the more modest ones waited until the main lights went off. In the dim red glow, the interior of Selene now had a fantastic appearance, One that would have been utterly inconceivable when she left Port Roris a few hours before. Twenty-two men and women, most of them stripped down to their underclothing, lay sprawled across the seats or along the floor. A few lucky ones were already snoring, but for most, sleep would not come as easily as that.

  Captain Harris had chosen a position at the very rear of the cruiser; in fact, he was not in the cabin at all, but in the tiny air-lock galley. It was a good vantage point. Now that the communicating door had been slid back, he could look the whole length of the cabin and keep an eye on everyone inside it.

  He folded his uniform into a pillow, and lay down on the unyielding floor. It was six hours before his watch was due, and he hoped he could get some sleep before then.

  Sleep! The last hours of his life were ticking away, yet he had nothing better to do. How well do condemned men sleep, he wondered, in the night that will end with the gallows?

  He was so desperately tired that even this thought brought no emotion. The last thing he saw, before consciousness slipped away, was Dr. McKenzie taking yet another temperature reading and carefully plotting it on his chart, like an astrologer casting a horoscope.

  Fifteen meters above—a distance that could be covered in a single stride under this low gravity—morning had already come. There is no twilight on the Moon, but for many hours the sky had held the promise of dawn. Stretching far ahead of the sun was the glowing pyramid of the zodiacal light, so seldom seen on Earth. With infinite slowness it edged its way above the horizon, growing brighter and brighter as the moment of sunrise approached. Now it had merged into the opalescent glory of the corona; and now, a million times more brilliant than either, a thin thread of fire began to spread along the horizon as the sun made its reappearance after fifteen days of darkness. It would take more than an hour for it to lift itself clear of the sky line, so slowly did the Moon turn on its axis, but the night had already ended.

  A tide of ink was swiftly ebbing from the Sea of Thirst, as the fierce light of dawn swept back the darkness. Now the whole drab expanse of the Sea was raked with almost horizontal rays. Had there been anything showing above its surface, this grazing light would have thrown its shadow for hundreds of meters, revealing it at once to any who were searching.

  But there were no searchers there. Duster One and Duster Two were busy on their fruitless quest in Crater Lake, fifteen kilometers away. They were still in darkness; it would be another two days before the sun rose above the surrounding peaks, though their summits were already blazing with the dawn. As the hours passed, the sharp-edged line of light would creep down the flanks of the mountains—sometimes moving no faster than a man could walk—until the sun climbed high enough for its rays to strike into the crater.

  But man-made light was already shining there, flashing among the rocks as the searchers photographed the slides that had come sweeping silently down the mountains when the Moon trembled in its sleep. Within an hour, those photographs would have reached Earth; in another two, all the inhabited worlds would have seen them.

  It would be very bad for the tourist business.

  When Captain Harris awoke, it was already much hotter. Yet it was not the now oppressive heat that had interrupted his sleep, a good hour before he was due to go on watch.

  Though he had never spent a night aboard her, Pat knew all the sounds that Selene could make. When the motors were not running, she was almost silent; one had to listen carefully to notice the susurration of the air pumps and the low throb of the cooling plant. Those sounds were still there, as they had been before he went to sleep. They were unchanged; but they had been joined by another.

  It was a barely audible whisper, so faint that for a moment he could not be sure he was not imagining it. That it should have called to his subconscious mind across the barriers of sleep seemed quite incredible. Even now that he was awake, he could not identify it, or decide from which direction it came.

  Then, abruptly, he knew why it had awakened him. In a second, the sogginess of sleep had vanished. He got quickly to his feet, and pressed his ear against the air-lock door, for that mysterious sound was coming, from outside the hull.

  Now he could hear it, faint but distinct, and it set his skin crawling with apprehension. There could be no doubt; it was the sound of countless dust grains whispering past Selene’s walls like a ghostly sandstorm. What did it mean? Was the Sea once more on the move? If so, would it take Selene with it? Yet there was not the slightest vibration or sense of motion in the cruiser itself; only the outside world was rustling past.

  Very quietly, being careful not to disturb his sleeping companions, Pat tiptoed into the darkened cabin. It was Dr. McKenzie’s watch. The Scientist was hunched up in the pilot’s seat, staring out through the blinded windows. He turned round as Pat approached, and whispered: “Anything wrong at your end?”

  “I don’t know—come and see.”

  Back in the galley, they pressed their ears against the outer door, and listened for a long time to that mysterious crepitation. Presently McKenzie said: “The dust’s moving, all right—but I don’t see why. That gives us another puzzle to worry about.”

  “Another?”

  “Yes. I don’t understand what’s happening to the temperature. It’s still going up, but nothing like as fast as it should.”

  The physicist seemed really annoyed that his calculations had proved incorrect, but to Pat this was the first piece of good news since the disaster.

  “Don’t look so miserable about it; we all make mistakes. And if this one gives us a few more days to live, I’m certainly not complaining.”

  “But I couldn’t have made a mistake. The math is elementary. We know how much heat twenty-two people generate, and it must go somewhere.”

  “They won’t produce so much heat when they’re sleeping; maybe that explains it.”

  “You don’t think I’d overlook anything so obvious as that!” said the scientist testily. “It helps, but it isn’t enough. There’s some other reason why we’re not getting as hot as we should.”

  “Let’s just accept the fact and be thankful,” said Pat. “Meanwhile, what about this noise?”

  With obvious reluctance, McKenzie switched his mind to the new problem.

  “The dust’s moving, but we aren’t, so it’s probably merely a local effect. In fact, it only seems to be happening at the back of the cabin. I wonder if that has any significance.” He gestured to the bulkhead behind them. “What’s on the other side of this?”

  “The motors, oxygen reserve, cooling equipment . . .”

  “_Cooling_ equipment! Of course! I remember noticing that when I came aboard. Our radiator fins are back there, aren’t they?”

  “That’s right.”

  “_Now_ I see what’s happened. They’ve got so hot that the dust is circulating, like any liquid that’s heated. There’s a dust fountain outside, and it’s carrying away our surplus heat. With any luck, the temperature will stabilize now. We won’t be comfortable, but we can survive.”

  In the crimson gloom, the two men looked at each other with a dawning hope. Then Pat said slowly: “I’m sure that’s the explanation. Perhaps our luck’s beginning to turn.”

  He glanced at his watch, and did a quick mental calculation.

  “The sun’s rising over the Sea about now. Base will have the dust-skis out looking for us, and they must know our approximate position. Ten to one they’ll find us in a few hours.”

  “Should we tell the Commodore?”

  “No,
let him sleep. He’s had a harder day than any of us. This news can wait until morning.”

  When McKenzie had left him, Pat tried to resume his interrupted sleep. But he could not do so; he lay with eyes open in the faint red glow, wondering at this strange turn of fate. The dust that had swallowed and then had threatened to broil them had now come to their aid, as its convection currents swept their surplus heat up to the surface. Whether those currents would continue to flow when the rising sun smote the Sea with its fall fury, he could not guess.

  Outside the wall, the dust still whispered past, and suddenly Pat was reminded of an antique hourglass he had once been shown as a child. When you turned it over, sand poured through a narrow constriction into the lower chamber, and its rising level marked the passage of the minutes and the hours.

  Before the invention of clocks, myriads of men must have had their days divided by such falling grains of sand. But none until now, surely, had ever had his life span metered out by a fountain of rising dust.

  CHAPTER SEVEN

  In Clavius City, Chief Administrator Olsen and Tourist Commissioner Davis had just finished conferring with the Legal Department. It had not been a cheerful occasion; much of the time had been spent discussing the waivers of responsibility which the missing tourists had signed before they boarded Selene. Commissioner Davis had been much against this when the trips were started, on the grounds that it would scare away customers, but the Administration’s lawyers had insisted. Now he was very glad that they had had their way.

  He was glad, also, that the Port Roris authorities had done the job properly; matters like this were sometimes treated as unimportant formalities and quietly ignored. There was a full list of signatures for Selene’s passengers—with one possible exception that the lawyers were still arguing about.

  The incognito Commodore had been listed as R. S. Hanson, and it looked very much as if this was the name he had actually signed. The signature was, however, so illegible that it might well have been “Hansteen.” Until a facsimile was radioed from Earth, no one would be able to decide this point. It was probably unimportant. Because the Commodore was traveling on official business, the Administration was bound to accept some responsibility for him. And for all the other passengers, it was responsible morally, if not legally.