Another hour passed on Ganymede. Hunt and the engineers returned to the lab to reappraise the experiment in light of what Cummings had told them. They called the base commander, reported the situation, and agreed to prepare a more intensive test for the Ganymean device. Then, while Towers and Mullen reexamined the data collected earlier, Hunt and Carizan toured the base to beg, borrow or steal some seismic monitoring equipment to add to their instruments. Suitable detectors were finally located in one of the warehouses, where they were kept as spares for a seismic outstation about three miles from the base, and the team began planning the afternoon's activities. By this time their excitement was mounting rapidly, but even more their curiosity; if, after all, the machine was an emitter of gravity pulses, what purpose did it serve?

One thousand five hundred million miles from Ganymede, not far from the mean orbit of Uranus, a communications subprocessor interrupted the operation of its supervisory computer. The computer activated a code-conversion routine and passed a top priority message on to the master-system monitor.

A transmission had been received from a standard Model 17 Mark 3B Distress Beacon.

The surface transporter climbed smoothly above the eternal veil of methane-ammonia haze that cloaked Pithead Base and leveled out onto a southerly course. For nearly two hours it skimmed over an unchanging wilderness of a stormy sea sculptured in ice and half immersed in a sullen ocean of mist. Occasional outcrops of rock added texture to the scene, standing black against the ghostly radiance induced by the serene glow of Jupiter's enormous rainbow disk. And then the cabin view screen showed a tight group of perhaps half a dozen silver spires jutting skywards from just over the horizon ahead--the huge thermonuclear Vega shuttles that stood guard over Ganymede Main Base.

After taking refreshments at Main, Hunt's party joined other groups bound for J5 and boarded one of the Vegas. Soon afterward they were streaking into space and Ganymede rapidly became just a smooth, featureless snowball behind them. Ahead, a pinpoint of light steadily elongated and enlarged, and then resolved itself into the awe-inspiring, majestic, mile-and-a-quarter-long Jupiter Five Mission command ship, hanging alone in the void; Jupiter Four had departed the week before, bound for Callisto where it would take up permanent orbit. The computers and docking radars guided the Vega gently to rest inside the cavernous forward docking bay, and within minutes the arrivals were walking into the immense city of metal.

Danchekker promptly disappeared to discuss with the J5's scientists the latest details of their studies of the terrestrial animal samples from Pithead. Without shame or conscience Hunt spent a glorious twenty-four hours totally relaxing, doing nothing. He enjoyed many rounds of drinks and endless yarns with Jupiter Five crew members he had become friendly with on the long voyage out from Earth, and found unbounded pleasure in the almost forgotten sense of freedom that came with simply sauntering unencumbered along the seemingly interminable expanses of the ship's corridors and vast decks. He felt intoxicated with well-being--exuberant. Just being back on Jupiter Five again seemed to bring him nearer to Earth and to things that were familiar. In a sense he was home. This tiny, manmade world, an island of light and life and warmth drifting through an infinite ocean of emptiness, was no longer the cold and alien shell that he had boarded high above Luna more than a year ago. It now seemed to him a part of Earth itself.

Hunt spent the second day paying social calls on some of J5's scientific personnel, exercising in one of the ship's lavishly equipped gymnasiums and cooling off afterward with a swim. A little while later, enjoying a well-earned beer in one of the bars and debating with himself what to do about dinner, he found himself talking to a medical officer who was snatching a quick refresher after coming off duty. Her name was Shirley. To their mutual surprise it turned out that Shirley had studied at Cambridge, England, and had rented a flat not two minutes' walk from Hunt's own student-day lodgings. Before very long one of those instant friendships that springs up out of nowhere was bursting into full bloom. They dined together and spent the rest of the evening talking and laughing and drinking, and drinking and laughing and talking. By midnight it had become evident that there would be no sudden parting of the ways. Next morning he felt better than he had for what he was sure was an unhealthily long time. That, he told himself, was surely what medical officers were supposed to make people feel like.

On the following day he rejoined Danchekker. The results of the two years of work that Hunt and Danchekker had spearheaded were by now a subject of worldwide acclaim, and the names of the two scientists had been in the limelight as a consequence. The Jupiter Five Mission director, Joseph B. Shannon, an Air Force colonel prior to world demilitarization fifteen years earlier, had been informed of their presence on the ship and had invited them to join him for lunch. Accordingly, halfway through the official day, they found themselves sitting at a table in the director's dining room, savoring the mellow euphoria that comes with cigars and brandy after the final course and obliging Shannon with their personal accounts of the other sensational discovery that had rocked the scientific world during those two years--the discovery of Charlie and the Lunarians. It ranked in sensationalism with that of the Ganymeans.

The Ganymeans had turned up later, when the shafts driven down into the ice below Pithead had penetrated to the Ganymean spacecraft. Some time before that discovery, exploration of the Lunar surface had yielded traces of yet another technologically advanced civilization that had flourished in the Solar System long before that of Man. This race was given the name "Lunarians," again to commemorate the place where the first finds had been made, and was known to have reached its peak some fifty thousand years before--during the final cold period of the Pleistocene Ice Age. Charlie, a spacesuited corpse found well-preserved beneath debris and rubble not far from Copernicus, had constituted the first find of all and had provided the clues that marked the starting point from which the story of the Lunarians was eventually reconstructed.

The Lunarians had proved to be fully human in every detail. Once this fact was established, the problem that presented itself was that of explaining where the Lunarians had come from. Either they had originated on Earth itself as a till-then unsuspected civilization that had emerged prior to the existence of modern Man, or they had originated somewhere else. There were no other possibilities open to consideration.

But for a long time both possibilities seemed to be ruled out. If an advanced society had once flourished on Earth, surely centuries of archaeological excavation should have produced abundant evidence of it. On the other hand, to suppose that they had originated elsewhere would require a process of parallel evolution--a violation of the accepted principles of random mutation and natural selection. The Lunarians therefore, being neither from Earth nor from anywhere else, couldn't exist. But they did. The unraveling of this seemingly insoluble mystery had brought Hunt and Danchekker together and had occupied them, along with hundreds of experts from just about all the world's major scientific institutions, for over two years.

"Chris insisted right from the beginning that Charlie, and presumably all the rest of the Lunarians too, could only have descended from the same ancestors as we did." Hunt spoke through a swirling tobacco haze while Shannon listened intently. "I didn't want to argue with him on that, but I couldn't go along with the conclusion that seemed to go with it--that they must, therefore, have originated on Earth. There would have to be traces of them around, and there weren't."