He called again into the reverberant silence, and again there was no direct reply – only that sense of watchful companionship. Very well; he would find the answers for himself.
Some were obvious; whoever or whatever they were, they were interested in Mankind. They had tapped and stored his memories, for their own inscrutable purposes. And now they had done the same with his deepest emotions, sometimes with his cooperation, sometimes without.
He did not resent that; indeed, the very processing he had experienced made such childish reactions impossible. He was beyond love and hate and desire and fear – but he had not forgotten them, and could still understand how they ruled the world of which he had once been part. Was that the purpose of the exercise? If so, for what ultimate goal?
He had become a player in a game of gods, and must learn the rules as he went along.
The jagged rocks of the four tiny outer moons, Sinope, Pasiphae, Carme, and Ananke, flickered briefly across his field of consciousness; then came Elara, Lysithea, Himalia, and Leda at half their distance from Jupiter. He ignored them all; now the pock-marked face of Callisto lay ahead.
Once, twice, he orbited the battered globe, larger than Earth’s own Moon, while senses of which he had been unaware probed its outer layers of ice and dust. His curiosity was quickly satisfied; the world was a frozen fossil, still bearing the marks of collisions that, aeons ago, must have come close to shattering it. One hemisphere was a giant bull’s-eye, a series of concentric rings where solid rock had once flowed in kilometre-high ripples under some ancient hammer blow from space.
Seconds later, he was circling Ganymede. Now there was a far more complex and interesting world; though so near to Callisto, and almost the same size, it presented an utterly different appearance. There were, it was true, numerous craters – but most of them seemed to have been, quite literally, ploughed back into the ground. The most extraordinary feature of the Ganymedean landscape was the presence of meandering stripes, built up from scores of parallel furrows a few kilometres apart. This grooved terrain looked as if it had been produced by armies of intoxicated ploughmen, weaving back and forth across the face of the satellite.
In a few revolutions, he saw more of Ganymede than all the space probes ever sent from Earth, and filed away the knowledge for future use. One day it would be important; he was sure of that, though he did not know why – any more than he understood the impulse that was now driving him so purposefully from world to world.
As, presently, it brought him to Europa. Though he was still largely a passive spectator, he was aware now of a rising interest, a focusing of attention – a concentration of will. Even if he was a puppet in the hands of an unseen and uncommunicative master, some of the thoughts of that controlling influence leaked – or were allowed to leak – into his own mind.
The smooth, intricately patterned globe now, rushing toward him bore little resemblance either to Ganymede or Callisto. It looked organic; the network of lines branching and intersecting over its entire surface was uncannily like a world-spanning system of veins and arteries.
The endless ice fields of a frigid waste, far colder than the Antarctic, stretched beneath him. Then, with brief surprise, he saw that he was passing over the wreckage of a spaceship. He recognized it instantly as the ill-fated Tsien, featured in so many of the video newscasts he had analysed. Not now – not now – there would be ample opportunity later.
Then he was through the ice, and into a world as unknown to his controllers as to himself.
It was an ocean world, its hidden waters protected from the vacuum of space by a crust of ice. In most places the ice was kilometres thick, but there were lines of weakness where it had cracked open and torn apart. Then there had been a brief battle between two implacably hostile elements that came into direct contact on no other world in the Solar System. The war between Sea and Space always ended in the same stalemate; the exposed water simultaneously boiled and froze, repairing the armour of ice.
The seas of Europa would have frozen completely solid long ago without the influence of nearby Jupiter. Its gravity continually kneaded the core of the little world; the forces that convulsed Io were working there, though with much less ferocity. As he skimmed across the face of the deep, he saw everywhere the evidence of that tug-of-war between planet and satellite.
And he both heard and felt it, in the continual roar and thunder of submarine earthquakes, the hiss of escaping gases from the interior, the infrasonic pressure waves of avalanches sweeping over the abyssal plains. By comparison with the tumultuous ocean that covered Europa, even the noisy seas of Earth were silent.
He had not lost his sense of wonder, and the first oasis filled him with delighted surprise. It extended for almost a kilometre around a tangled mass of pipes and chimneys deposited by mineral brines gushing from the interior. Out of that natural parody of a Gothic castle, black, scalding liquids pulsed in a slow rhythm, as if driven by the beating of some mighty heart. And, like blood, they were the authentic sign of life itself.
The boiling fluids drove back the deadly cold leaking down from above, and formed an island of warmth on the seabed. Equally important, they brought from Europa’s interior all the chemicals of life. There, in an environment where none had expected it, were energy and food, in abundance.
Yet it should have been expected; he remembered that, only a lifetime ago, such fertile oases had been discovered in the deep oceans of Earth. Here they were present on an immensely larger scale, and in far greater variety.
In the tropical zone close to the contorted walls of the ‘castle’ were delicate, spidery structures that seemed to be the analogy of plants, though almost all were capable of movement. Crawling among these were bizarre slugs and worms, some feeding on the plants, others obtaining their food directly from the mineral-laden waters around them. At greater distances from the source of heat – the submarine fire around which all the creatures warmed themselves – were sturdier, more robust organisms, not unlike crabs or spiders.
Armies of biologists could have spent lifetimes studying that one small oasis. Unlike the Palaeozoic terrestrial seas, it was not a stable environment, so evolution had progressed swiftly here, producing multitudes of fantastic forms. And they were all under indefinite stay of execution; sooner or later, each fountain of life would weaken and die, as the forces that powered it moved their focus elsewhere.
Again and again, in his wanderings across the Europan seabed, he encountered the evidence of such tragedies. Countless circular areas were littered with the skeletons and mineral-encrusted remains of dead creatures, where entire chapters of evolution had been deleted from the book of life.
He saw huge, empty shells formed like convoluted trumpets as large as a man. There were clams of many shapes – bivalves, and even trivalves. And there were spiral stone patterns, many metres across, which seemed an exact analogy of the beautiful ammonites that disappeared so mysteriously from Earth’s oceans at the end of the Cretaceous Period.
Searching, seeking, he moved back and forth over the face of the abyss. Perhaps the greatest of all the wonders he met was a river of incandescent lava, flowing for a hundred kilometres along a sunken valley. The pressure at that depth was so great that the water in contact with the red-hot magma could not flash into steam, and the two liquids coexisted in an uneasy truce.
There, on another world and with alien actors, something like the story of Egypt had been played long before the coming of man. As the Nile had brought life to a narrow ribbon of desert, so this river of warmth had vivified the Europan deep. Along its banks, in a band never more than two kilometres wide, species after species had evolved and flourished and passed away. And at least one had left a monument behind it.
At first, he thought that it was merely another of the encrustations of mineral salts that surrounded almost all the thermal vents. However, as he came closer, he saw that it was not a natural formation, but a structure created by intelligence. Or perhaps by instinct; on Earth, the termites reared castles that were almost equally imposing, and the web of a spider was more exquisitely designed.
The creatures that had lived there must have been quite small, for the single entrance was only half a metre wide. That entrance – a thick-walled tunnel, made by heaping rocks on top of each other – gave a clue to the builders’ intentions. They had reared a fortress, there in the flickering glow not far from the banks of their molten Nile. And then they had vanished.