In the banked communications racks of Traffic Control, Earthside North, an electronic memory stirred uneasily. The time was one second past twenty hundred hours GMT: a pattern of pulses that should arrive automatically on every hour had failed to make its appearance.
With a swiftness beyond human thought, the handful of cells and microscopic relays looked for instructions. “WAIT FIVE SECONDS”, said the coded orders. “IF NOTHING HAPPENS, CLOSE CIRCUIT 10011001.”
The minute portion of the traffic computer as yet concerned with the problem waited patiently for this enormous period of time — long enough to make a hundred million twenty figure additions, or to print most of the contents of the Library of Congress. Then it closed circuit 10011001.
High above the surface of the Moon, from an antenna which, curiously enough, was aimed directly at the face of the Earth, a radio pulse launched itself into space. In a sixth of a second it had flashed the fifty thousand kilometers to the relay satellite known as Lagrange II, directly in the line between Moon and Earth. Another sixth of a second and the pulse had returned, much amplified, flooding Earthside North from pole to equator.
In terms of human speech, it carried a simple message. “HELLO, SELENE”, the pulse said. “I AM NOT RECEIVING YOUR BEACON. PLEASE REPLY AT ONCE.”
The computer waited for another five seconds. Then it sent out the pulse again, and yet again. Geological ages had passed in the world of electronics, but the machine was infinitely patient.
Once more, it consulted its instructions. Now they said: “CLOSE CIRCUIT 10101010.” The computer obeyed. In Traffic Control, a green light flared suddenly to red, a buzzer started to saw the air with its alarm. For the first time, men as well as machines became aware that there was trouble, somewhere on the Moon.
The news spread slowly at first, for the Chief Administrator took a very poor view of unnecessary panic. So, still more strongly, did the Tourist Commissioner; nothing was worse for business than alerts and emergencies — even when, as happened in nine cases out of ten, they proved to be due to blown fuses, tripped cutouts, or oversensitive alarms. But on a world like the Moon, it was necessary to be on one's toes. Better be seared by imaginary crises than fail to react to real ones.
It was several minutes before Commissioner Davis reluctantly admitted that this looked like a real one. Selene's automatic beacon had failed to respond on one earlier occasion, but Pat Harris had answered as soon as he had been called on the cruiser's assigned frequency. This time, there was silence. Selene had not even replied to a signal sent out on the carefully guarded MOONCRASH band, reserved solely for emergencies. It was this news that brought the Commissioner hurrying from the Tourist Tower along the buried glideway into Clavius City.
At the entrance to the Traffic Control center, he met the Chief Engineer, Earthside. That was a bad sign; it meant that someone thought that rescue operations would be necessary. The two men looked at each other gravely, each obsessed by the same thought.
“I hope you don't need me”, said Chief Engineer Lawrence. “Where's the trouble? All I know is that a Mooncrash signal's gone out. What ship is it?”
“It's not a ship. It's Selene; she's not answering, from the Sea of Thirst.”
“My God — if anything's happened to her out there, we can only reach her with the dust-skis. I always said we should have two cruisers operating, before we started taking out tourists.”
“That's what I argued — but Finance vetoed the idea. They said we couldn't have another until Selene proved she could make a profit.”
“I hope she doesn't make a headline instead”, said Lawrence grimly. “You know what I think about bringing tourists to the Moon.”
The Commissioner did, very well; it had long been a bone of contention between them. For the first time, he wondered if the Chief Engineer might have a point.
It was, as always, very quiet in Traffic Control. On the great wall maps, the green and amber lights flashed continuously, their routine messages unimportant against the clamor of that single, flaring red. At the Air, Power, and Radiation consoles, the duty officers sat like guardian angels, watching over the safety of one quarter of a world.
“Nothing new”, reported the Ground Traffic officer. “We're still completely in the dark. All we know is that they're somewhere out in the Sea.”
He traced a circle on the large-scale map.
“Unless they're fantastically off course, they must be in that general area. On the nineteen hundred hours check, they were within a kilometer of their planned route. At twenty hundred, their signal had vanished, so whatever happened took place in that sixty minutes.”
“How far can Selene travel in an hour?” someone asked.
“Flat out, a hundred and twenty kilometers”, replied the Commissioner. “But she normally cruises at well under a hundred. You don't hurry on a sight-seeing tour.”
He stared at the map, as if trying to extract information from it by the sheer intensity of his gaze.
“If they're out in the Sea, it won't take long to find them. Have you sent out the dust-skis?”
“No, sir; I was waiting for authorization.”
Davis looked at the Chief Engineer, who outranked anyone on this side of the Moon except Chief Administrator Olsen himself. Lawrence nodded slowly.
“Send them out”, he said. “But don't expect results in a hurry. It will take awhile to search several thousand square kilometers — especially at night. Tell them to work over the route from the last reported position, one ski on either side of it, so that they sweep the widest possible band.”
When the order had gone out, Davis asked unhappily: “What do you think could have happened?”
“There are only a few possibilities. It must have been sudden, because there was no message from them. That usually means an explosion.”
The Commissioner paled; there was always the chance of sabotage, and no one could ever guard against that. Because of their vulnerability, space vehicles, like aircraft before them, were an irresistible attraction to a certain type of criminal. Davis thought of the Venus-bound liner Argo, which had been destroyed with two hundred men, women, and children aboard, because a maniac had a grudge against a passenger who scarcely knew him.
“And then there's collision”, continued the Chief Engineer. “She could have run into an obstacle.”
“Harris is a very careful driver”, said the Commissioner. “He's done this trip scores of times.”
“Everyone can make mistakes; it's easy to misjudge your distance when you're driving by earthlight.”
Commissioner Davis barely heard him; he was thinking of all the arrangements he might have to make if the worst came to the worst. He'd better start by getting the Legal Branch to check the indemnity forms. If any relatives started suing the Tourist Commission for a few million dollars, that would undo his entire publicity campaign for the next year — even if he won.
The Ground Traffic officer gave a nervous cough.
“If I might make a suggestion”, he said to the Chief Engineer. “We could call Lagrange. The astronomers up their may be able to see something.”
“At night?” asked Davis skeptically. “From fifty thousand kilometers up?”
“Easily, if her searchlights are still burning. It's worth trying.”
“Excellent idea”, said the Chief Engineer. “Do that right away.”
He should have thought of that himself, and wondered if there were any other possibilities he had overlooked. This was not the first occasion he had been forced to pit his wits against this strange and beautiful world, so breath-taking in her moments of magic — so deadly in her times of peril. She would never be wholly tamed, as Earth had been, and perhaps that was just as well. For it was the lure of the untouched wilderness and the faint but ever-present hint of danger that now brought the tourists as well as the explorers across the gulfs of space. He would prefer to do without the tourists — but they helped to pay his salary.
And now he had better start packing. This whole crisis might evaporate, and Selene might turn up again quite unaware of the panic she had caused. But he did not think this would happen, and his fear deepened to certainty as the minutes passed. He would give her another hour; then he would take the suborbital shuttle to Port Roris and to the realm of his waiting enemy, the Sea of Thirst.
When the PRIORITY RED signal reached Lagrange, Thomas Lawson, Ph. D., was fast asleep. He resented the interruption; though one needed only two hours' sleep in twenty-four when living under zero gravity, it seemed a little unfair to lose even that. Then he grasped the meaning of the message, and was fully awake. At last it looked as if he would be doing something useful here.
Tom Lawson had never been very happy about this assignment; he had wanted to do scientific research, and the atmosphere aboard Lagrange II was much too distracting. Balanced here between Earth and Moon, in a cosmic tightrope act made possible by one of the obscurer consequences of the law of gravitation, the satellite was an astronautical maid-of-all-work. Ships passing in both directions took their fixes from it, and used it as a message center — though there was no truth in the rumor that they stopped to pick up mail. Lagrange was also the relay station for almost all lunar radio traffic, because the whole earthward-facing side of the Moon lay spread beneath it.
The hundred-centimeter telescope had been designed to look at objects billions of times farther away than the Moon, but it was admirably suited for this job. From so close at hand, even with the low power, the view was superb. Tom seemed to be hanging in space immediately above the Sea of Rains, looking down upon the jagged peaks of the Apennines as they glittered in the morning light. Though he had only a sketchy knowledge of the Moon's geography, he could recognize at a glance the great craters of Archimedes and Plato, Aristillus and Eudoxus, the dark scar of the Alpine Valley, and the solitary pyramid of Pico, casting its long shadow across the plain.
But the daylight region did not concern him; what he sought lay in the darkened crescent where the sun had not yet risen. In some ways, that might make his task simpler. A signal lamp — even a hand torch — would be easily visible down there in the night. He checked the map coordinates, and punched the control buttons. The burning mountains drifted out of his field of view, and only blackness remained, as he stared into the lunar night that had just swallowed more than twenty men and women.
At first he could see nothing — certainly no winking signal light, flashing its appeal to the stars. Then, as his eyes grew more sensitive, he could see that this land was not wholly dark. It was glimmering with a ghostly phosphorescence as it lay bathed in the earthlight, and the longer he looked, the more details he could see.
There were the mountains to the east of Rainbow Bay, waiting for the dawn that would strike them soon. And there — my God, what was that star shining in the darkness? His hopes soared, then swiftly crashed. That was only the lights of Port Roris, where even now men would be waiting anxiously for the results of his survey.
Within a few minutes, he had convinced himself that a visual search was useless. There was not the slightest chance that he could see an oblect no bigger than a bus, down there in that faintly luminous landscape. In the daytime, it would have been different; he could have spotted Selene at once by the long shadow she cast across the Sea. But the human eye was not sensitive enough to make this search by the light of the waning Earth, from a height of fifty thousand kilometers.
This did not worry Tom. He had scarcely expected to see anything, on this first visual survey. It was a century and a half since astronomers had had to rely upon their eyesight; today, they had far more delicate weapons — a whole armory of light amplifiers and radiation detectors. One of these, he was certain, would be able to find Selene.
He would not have been so sure of this had he known that she was no longer upon the surface of the Moon.