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.
They could not have left more than a few centuries before. The walls of the fortress, built from irregularly shaped rocks that must have been collected with great labour, were covered with only a thin crust of mineral deposits. One piece of evidence suggested why the stronghold had been abandoned. Part of the roof had fallen in, perhaps owing to the continual earthquakes; and in an underwater environment, a fort without a roof was wide open to an enemy.
He encountered no other sign of intelligence along the river of lava. Once, however, he saw something uncannily like a crawling man - except that it had no eyes and no nostrils, only a huge, toothless mouth that gulped continuously, absorbing nourishment from the liquid medium around it.
Along the narrow band of fertility in the deserts of the deep, whole cultures and even civilizations might have risen and fallen, armies might have marched (or swum) under the command of Europan Tamberlanes or Napoleons. And the rest of their world would never have known, for all those oases of warmth were as isolated from one another as the planets themselves. The creatures who basked in the glow of the lava river, and fed around the hot vents, could not cross the hostile wilderness between their lonely islands, If they had ever produced historians and philosophers, each culture would have been convinced that it was alone in the Universe.
Yet even the space between the oases was not altogether empty of life; there were hardier creatures who had dared its rigours. Often swimming overhead were the Europan analogues of fish - streamlined torpedoes, propelled by vertical tails, steered by fins along their bodies. The resemblance to the most successful dwellers in Earth's oceans was inevitable; given the same engineering problems, evolution must produce very similar answers. As witness the dolphin and the shark - superficially almost identical, yet from far distant branches of the tree of life.
There was, however, one very obvious difference between the fish of the Europan seas and those in terrestrial oceans; they had no gills, for there was hardly a trace of oxygen to be extracted from the waters in which they swam. Like the creatures around Earth's own geothermal vents, their metabolism was based on sulphur compounds, present in abundance in the near-volcanic environment.
And very few had eyes. Apart from the flickering glow of the rare lava outpourings, and occasional bursts of bioluminescence from creatures seeking mates, or hunters questing prey, it was a lightless world.
It was also a doomed one. Not only were its energy sources sporadic and constantly shifting, but the tidal forces that drove them were steadily weakening. Even if they developed true intelligence, the Europans must perish with the final freezing of their world.
They were trapped between fire and ice.
37
Estrangement
I'm truly sorry, old friend, to be the bearer of such bad news, but Caroline has asked me, and you know how I feel about you both.
"And I don't think it can be such a surprise. Some of the remarks you've made to me over the last year have hinted at it... and you know how bitter she was when you left Earth.
"No, I don't believe there's anyone else. If there was, she'd have told me... But sooner or later - well, she's an attractive young woman.
"Chris is fine, and of course he doesn't know what's happening. At least he won't be hurt. He's too young to understand, and children are incredibly... elastic? - just a minute, I'll have to key my thesaurus... ah, resilient.
"Now to things that may seem less important to you. Everyone is still trying to explain that bomb detonation as an accident, but of course nobody believes it. Because nothing else has happened, the general hysteria has died down; we're left with what one of your commentators has called the 'looking-over-the-shoulder syndrome' ".
"And someone has found a hundred-year-old poem that sums up the situation so neatly that everybody's quoting it. It's set in the last days of the Roman Empire, at the gates of a city whose oc
cupants are waiting for invaders to arrive. The emperor and dignitaries are all lined up in their most costly togas, ready with speeches of welcome. The senate has closed, because any laws it passes today will be ignored by the new masters.
"Then, suddenly, a dreadful piece of news arrives from the frontier. There aren't any invaders. The reception committee breaks up in confusion; everyone goes home muttering disappointedly, "Now what will happen to us? Those people were a kind of solution.
"There's just one slight change needed to bring the poem up to date. It's called 'Waiting for the Barbarians' - and this time, we are the barbarians. And we don't know what we're waiting for, but it certainly hasn't arrived.
"One other item. Had you heard that Commander Bowman's mother died only a few days after the thing came to Earth? It does seem an odd coincidence, but the people at her nursing home say that she never showed the slightest interest in the news, so it couldn't possibly have affected her."
Floyd switched off the recording. Dimitri was right; he was not taken by surprise. But that made not the slightest difference; it hurt just as badly.
Yet what else could he have done? If he had refused to go on the mission - as Caroline had so clearly hoped - he would have felt guilty and unfulfilled for the remainder of his life. That would have poisoned his marriage; better this clean break, when physical distance softened the pain of separation. (Or did it? In some ways, it made things worse.) More important was duty, and the sense of being part of a team devoted to a single goal.
So Jessie Bowman was gone. Perhaps that was another cause for guilt. He had helped to steal her only remaining son, and that must have contributed to her mental breakdown. Inevitably, he was reminded of a discussion that Walter Curnow had started, on that very subject.
"Why did you choose Dave Bowman? He always struck me as a cold fish - not actually unfriendly, but whenever he came into the room, the temperature seemed to drop ten degrees."
"That was one of the reasons we did select him. He had no close family ties, except for a mother he didn't see very often. So he was the sort of man we could send on a long, open-ended mission."
"How did he get that way?"
"I suppose the psychologists could tell you. I did see his report, of course, but that was a long time ago. There was something about a brother who was killed - and his father died soon afterward, in an accident on one of the early shuttles. I'm not supposed to tell you this, but it certainly doesn't matter now."
It didn't matter; but it was interesting. Now Floyd almost envied David Bowman, who had come to that very spot a free man unencumbered by emotional ties with Earth.
No - he was deceiving himself. Even while the pain gripped his heart like a vice, what he felt for David Bowman was not envy, but pity.
38
Foamscape
The last beast he saw, before he left the oceans of Europa, was much the largest. It closely resembled one of the banyan trees from Earth's tropics, whose scores of trunks allow a single plant to create a small forest sometimes covering hundreds of square metres. The specimen, however, was walking, apparently on a trek between oases. If it was not one of the creatures that had destroyed Tsien, it certainly belonged to a very similar species.
Now he had learned all that he needed to know - or, rather, all that they needed to know. There was one more moon to visit; seconds later, the burning landscape of Io lay below him.
It was as he had expected. Energy and food were there in abundance, but the time was not yet ripe for their union. Around some of the cooler sulphur lakes, the first steps had been taken on the road to life, but before any degree of organization had occurred, all such bravely premature attempts were thrown back into the melting pot. Not until the tidal forces that drove Io's furnaces had lost their power, millions of years later, would there be anything to interest biologists on that seared and sterilized world.
He wasted little time on Io, and none at all on the tiny inner moons that skirted Jupiter's ghostly rings - themselves only pale shadows of the glory that was Saturn's. The greatest of worlds lay before him; he would know it as no man had ever done, or ever would.
The million-kilometre-long tendrils of magnetic force, the sudden explosions of radio waves, the geysers of electrified plasma wider than the planet Earth - they were as real and clearly visible to him as the clouds banding the planet in multihued glory. He could understand the complex pattern of their interactions, and realized that Jupiter was much more wonderful than anyone had ever guessed.
Even as he fell through the roaring heart of the Great Red Spot, with the lightning of its continent-wide thunderstorms detonating around him, he knew why it had persisted for centuries though it was made of gases far less substantial than those that formed the hurricanes of Earth. The thin scream of hydrogen wind faded as he sank into the calmer depths, and a sleet of waxen snowflakes - some already coalescing into barely palpable mountains of hydrocarbon foam - descended from the heights above. It was already warm enough for liquid water to exist, but there were no oceans there; that purely gaseous environment was too tenuous to support them.
He descended through layer after layer of cloud, until he entered a region of such clarity that even human vision could have scanned an area more than a thousand kilometres across. It was only a minor eddy in the vaster gyre of the Great Red Spot; and it held a secret that men had long guessed, but never proved.
Skirting the foothills of the drifting foam mountains were myriads of small, sharply-defined clouds, all about the same size and patterned with similar red and brown mottlings. They were small only as compared with the inhuman scale of their surroundings; the very least would have covered a fair-sized city.
They were clearly alive, for they were moving with slow deliberation along the flanks of the aerial mountains, browsing off their slopes like colossal sheep. And they were calling to each other in the metre band, their radio voices faint but clear against the cracklings and concussions of Jupiter itself.
Nothing less than living gasbags, they floated in the narrow zone between freezing heights and scorching depths. Narrow, yes - but a domain far larger than all the biosphere of Earth.
They were not alone. Moving swiftly among them were other creatures so small that they could easily have been overlooked. Some of them bore an almost uncanny resemblance to terrestrial aircraft and were of about the same size. But they too were alive - perhaps predators, perhaps parasites, perhaps even herdsmen.
A whole new chapter of evolution, as alien as that which he had glimpsed on Europa, was opening before him. There were jet-propelled torpedoes like the squids of the terrestrial oceans, hunting and devouring the huge gasbags. But the balloons were not defenceless; some of them fought backs with electric thunderbolts and with clawed tentacles like kilometre-long chainsaws.
There were even stranger shapes, exploiting almost every possibility of geometry - bizarre, translucent kites, tetrahedra, spheres, polyhedra, tangles of twisted ribbons.
The gigantic plankton of the Jovian atmosphere, they were designed to float like gossamer in the uprising currents, until they had lived long enough to reproduce; then they would be swept down into the depths to be carbonized and recycled in a new generation.
He was searching a world more than a hundred times the area of Earth, and though he saw many wonders, nothing there hinted of intelligence. The radio voices of the great balloons carried only simple messages of warning or of fear. Even the hunters, who might have been expected to develop higher degrees of organization, were like the sharks in Earth's oceans - mindless automata.
And for all its breathtaking size and novelty, the biosphere of Jupiter was a fragile world, a place of mists and foam, of delicate silken threads and paper-thin tissues spun from the continual snowfall of petrochemicals formed by lightning in the upper atmosphere. Few of its constructs were more substantial than soap bubbles; its most terrifying predators could be torn to shreds by even the feeblest of terrestrial carnivores.
Like E
uropa on a vastly grander scale, Jupiter was an evolutionary cul-de-sac. Consciousness would never emerge here; even if it did, it would be doomed to a stunted existence. A purely aerial culture might develop, but in an environment where fire was impossible, and solids scarcely existed, it could never even reach the Stone Age.
And now, as he hovered above the centre of a Jovian cyclone merely as large as Africa, he became aware once again of the presence controlling him. Moods and emotions were leaking into his own consciousness, though he could not identify any specific concepts or ideas. It was as if he were listening, outside a closed door, to a debate in progress, and in a language he could not understand. But the muffled sounds clearly conveyed disappointment, then uncertainty, then a sudden determination - though for what purpose he could not tell. Once again, he felt like a pet dog, able to share his master's changing moods but not to comprehend them.
And then the invisible leash was taking him down toward the heart of Jupiter. He was sinking through the clouds, below the level where any form of life was possible.
Soon he was beyond the reach of the last rays from the faint and distant Sun. The pressure and temperature were swiftly mounting; already it was above the boiling point of water, and he passed briefly through a layer of superheated steam. Jupiter was like an onion; he was peeling it away skin by skin, though as yet he had travelled only a fraction of the distance to its core.
Beneath the steam was a witches' brew of petrochemicals - enough to power for a million years all the internal-combustion engines that mankind had dyer built. It became thicker and denser; then, quite abruptly, it ended at a discontinuity only a few kilometres thick.
Heavier than any rocks on Earth, yet still a liquid, the next shell consisted of silicon and carbon compounds of a complexity that could have provided lifetimes of work for terrestrial chemists. Layer followed layer for thousands of kilometres, but as the temperature rose into the hundreds and then the thousands of degrees, the composition of the various strata became simpler and simpler. Halfway down to the core, it was too hot for chemistry; all compounds were torn apart, and only the basic elements could exist.