But the glory of the rings continually drew Bowman's eye away from the planet; in their complexity of detail, and delicacy of shading, they were a universe in themselves. In addition to the great main gap between the inner and outer rings, there were at least fifty other subdivisions or boundaries, where there were distinct changes in the brightness of the planet's gigantic halo. It was as if Saturn was surrounded by scores of concentric hoops, all touching each other, all so flat that they might have been cut from the thinnest possible paper. The system of the rings looked like some delicate work of art, or a fragile toy to be admired but never touched. By no effort of the will could Bowman really appreciate its true scale, and convince himself that the whole planet Earth, if set down here, would look like a ball bearing rolling round the rim of a dinner plate.
Sometimes a star would drift behind the rings, losing only a little of its brilliancy as it did so. It would continue to shine through their translucent material—though often it would twinkle slightly as some larger fragment of orbiting debris eclipsed it.
For the rings, as had been known since the nineteenth century, were not solid: that was a mechanical impossibility. They consisted of countless myriads of fragments—perhaps the remains of a moon that had come too close and had been torn to pieces by the great planet's tidal pull. Whatever their origin, the human race was fortunate to have seen such a wonder; it could exist for only a brief moment of time in the history of the Solar System.
As long ago as 1945, a British astronomer had pointed out that the rings were ephemeral; gravitational forces were at work which would soon destroy them. Taking this argument backward in time, it therefore followed that they had been created only recently—a mere two or three million years ago.
But no one had ever given the slightest thought to the curious coincidence that the rings of Saturn had been born at the same time as the human race.
Chapter 34
The Orbiting Ice
Discovery was now deep into the wide-ranging system of moons, and the great planet itself was less than a day ahead. The ship had long since passed the boundary set by outermost Phoebe, moving backward in a wildly eccentric orbit eight million miles from its primary. Ahead of it now lay Japetus, Hyperion, Titan, Rhea, Dione, Tethys, Enceladus, Mimas, Janus—and the rings themselves. All the satellites showed a maze of surface detail in the telescope, and Bowman had relayed back to Earth as many photographs as he could take. Titan alone—three thousand miles in diameter, and as large as the planet Mercury—would occupy a survey team for months; he could give it, and all its cold companions, only the briefest of glances. There was no need for more; already he was quite certain that Japetus was indeed his goal.
All the other satellites were pitted by occasional meteor craters—though these were much fewer than on Mars—and showed apparently random patterns of light and shade, with here and there a few bright spots that were probably patches of frozen gas. Japetus alone possessed a distinctive geography, and a very strange one indeed.
One hemisphere of the satellite, which, like its companions, turned the same face always toward Saturn, was extremely dark, and showed very little surface detail. In complete contrast, the other was dominated by a brilliant white oval, about four hundred miles long and two hundred wide. At the moment, only part of this striking formation was in daylight, but the reason for Japetus's extraordinary variations in brilliance was now quite obvious. On the western side of the moon's orbit, the bright ellipse was presented toward the Sun—and the Earth. On the eastern phase, the patch was turned away, and only the poorly reflecting hemisphere could be observed.
The great ellipse was perfectly symmetrical, straddling the equator of Japetus with its major axis pointing toward the poles; and it was so sharp-edged that it almost looked as if someone had carefully painted a huge white oval on the face of the little moon. It was completely flat, and Bowman wondered if it could be a lake of frozen liquid—though that would hardly account for its startlingly artificial appearance.
But he had little time to study Japetus on his way into the heart of the Saturnian system, for the climax of the voyage—Discovery's last perturbation maneuver—was rapidly approaching. In the Jupiter fly-by, the ship had used the gravitational field of the planet to increase her velocity. Now she must do the reverse; she had to lose as much speed as possible, lest she escape from the Solar System and fly on to the stars. Her present course was one designed to trap her, so that she would become another moon of Saturn, shuttling back and forth along a narrow, two-million-mile-long ellipse. At its near point it would almost graze the planet; at its far one, it would touch the orbit of Japetus.
The computers back on Earth, though their information was always three hours late, had assured Bowman that everything was in order. Velocity and altitude were correct; there was nothing more to be done, until the moment of closest approach.
The immense system of rings now spanned the sky, and already the ship was passing over its outermost edge. As he looked down upon them from a height of some ten thousand miles, Bowman could see through the telescope that the rings were made largely of ice, glittering and scintillating in the light of the Sun. He might have been flying over a snowstorm that occasionally cleared to reveal, where the ground should have been, baffling glimpses of night and stars.
As Discovery curved still closer toward Saturn, the Sun slowly descended toward the multiple arches of the rings. Now they had become a slim, silver bridge spanning the entire sky; though they were too tenuous to do more than dim the sunlight, their myriads of crystals refracted and scattered it in dazzling pyrotechnics. And as the Sun moved behind the thousand-mile-wide drifts of orbiting ice, pale ghosts of itself marched and merged across the sky, and the heavens were filled with shifting flares and flashes. Then the Sun sank below the rings, so that they framed it with their arches, and the celestial fireworks ceased.
A little later, the ship curved into the shadow of Saturn, as it made its closest approach over the night side of the planet. Above shone the stars and the rings; below lay a dimly visible sea of clouds. There were none of the mysterious patterns of luminosity that had glowed in the Jovian night; perhaps Saturn was too cold for such displays. The mottled cloudscape was revealed only by the ghostly radiance reflected back from the circling icebergs, still illuminated by the hidden Sun. But in the center of the arch there was a wide, dark gap, like the missing span of an uncompleted bridge, where the shadow of the planet lay across its rings.
Radio contact with Earth had been broken, and could not be resumed until the ship emerged from the eclipsing bulk of Saturn. It was perhaps as well that Bowman was too busy now to think of his suddenly enhanced loneliness; for the next few hours, every second would be occupied as he checked the braking maneuvers, already programmed by the computers on Earth.
After their months of idleness, the main thrusters began to blast out their miles-long cataracts of glowing plasma. Gravity returned, though briefly, to the weightless world of the control deck. And hundreds of miles below, the clouds of methane and frozen ammonia blazed with a light that they had never known before, as Discovery swept, a fierce and tiny sun, through the Saturnian night.
At last, the pale dawn lay ahead; the ship, moving more and more slowly now, was emerging into day. It could no longer escape from the Sun, or even from Saturn—but it was still moving swiftly enough to rise away from the planet until it grazed the orbit of Japetus, two million miles out.
It would take Discovery fourteen days to make that climb, as she coasted once more, though in reverse order, across the paths of all the inner moons. One by one she would cut through the orbits of Janus, Mimas, Enceladus, Tethys, Dione, Rhea, Titan, Hyperion . . . worlds bearing the names of gods and goddesses who had vanished only yesterday, as time was counted here.
Then she would meet Japetus, and must make her rendezvous. If she failed, she would fall back toward Saturn and repeat her twenty-eight-day ellipse indefinitely.
There would be no chance
for a second rendezvous if Discovery missed on this attempt. The next time around, Japetus would be far away, almost on the other side of Saturn.
It was true that they would meet again, when the orbits of ship and satellite meshed for a second time. But that appointment was so many years ahead that, whatever happened, Bowman knew he would not witness it.
Chapter 35
The Eye of Japetus
When Bowman had first observed Japetus, that curious elliptical patch, of brilliance had been partly in shadow, illuminated only by the light of Saturn. Now, as the Moon moved slowly along its seventy-nine-day orbit, it was emerging into the full light of day.
As he watched it grow, and Discovery rose more and more sluggishly toward her inevitable appointment, Bowman became aware of a disturbing obsession. He never mentioned it in his conversations—or, rather, his running commentaries—with Mission Control, because it might have seemed that he was already suffering from delusions.
Perhaps, indeed, he was; for he had half convinced himself that the bright ellipse set against the dark background of the satellite was a huge, empty eye, staring at him as he approached. It was an eye without a pupil, for nowhere could he see anything to mar its perfect blankness.
Not until the ship was only fifty thousand miles out, and Japetus was twice as large as Earth's familiar Moon, did he notice the tiny black dot at the exact center of the ellipse. But there was no time, then, for any detailed examination; the terminal maneuvers were already upon him.
For the last time, Discovery's main drive released its energies. For the last time, the incandescent fury of dying atoms blazed among the moons of Saturn. To David Bowman, the far-off whisper and rising thrust of the jets brought a sense of pride—and of sadness. The superb engines had done their duty with flawless efficiency. They had brought the ship from Earth to Jupiter to Saturn; now this was the very last time that they would ever operate. When Discovery had emptied her propellant tanks, she would be as helpless and inert as any comet or asteroid, a powerless prisoner of gravitation. Even when the rescue ship arrived a few years hence, it would not be an economical proposition to refuel her, so that she could fight her way back to Earth. She would be an eternally orbiting monument to the early days of planetary exploration.
The thousands of miles shrank to hundreds, and as they did so, the fuel gauges dropped swiftly toward zero. At the control panel, Bowman's eyes flickered anxiously back and forth over the situation display, and the improvised charts which he now had to consult for any real-time decisions. It would be an appalling anticlimax if, having survived so much, he failed to make rendezvous through lack of a few pounds of fuel. . . .
The whistle of the jets faded, as the main thrust died and only the verniers continued to nudge Discovery gently into orbit. Japetus was now a giant crescent that filled the sky; until this moment, Bowman had always thought of it as a tiny, insignificant object—as indeed it was compared with the world around which it circled. Now, as it loomed menacingly above him, it seemed enormous—a cosmic hammer poised to crush Discovery like a nutshell.
Japetus was approaching so slowly that it scarcely seemed to move, and it was impossible to tell the exact moment when it made the subtle change from an astronomical body to a landscape, only fifty miles below. The faithful verniers gave their last spurts of thrust, then closed down forever. The ship was in its final orbit, completing one revolution every three hours at a mere eight hundred miles an hour—all the speed that was required in this feeble gravitational field.
Discovery had become a satellite of a satellite.
Chapter 36
Big Brother
I'm coming round to the daylight side again, and it's just as I reported on the last orbit. This place seems to have only two kinds of surface material. The black stuff looks burned, almost like charcoal, and with the same kind of texture as far as I can judge in the telescope. In fact, it reminds me very much of burned toast. . . .
"I still can't make any sense of the white area. It starts at an absolutely sharp-edged boundary, and shows no surface detail at all. It could even be a liquid—it's flat enough. I don't know what impression you've got from the videos I've transmitted, but if you picture a sea of frozen milk you'll get the idea exactly.
"It could even be some heavy gas—no, I suppose that's impossible. Sometimes I get the feeling that it's moving, very slowly; but I can never be sure. . . .
"…I'm over the white area again, on my third orbit. This time I hope to pass closer to that mark I spotted at its very center, when I was on my way in. If my calculations are correct, I should go within fifty miles of it—whatever it is.
"…Yes, there's something ahead, just where I calculated. It's coming up over the horizon—and so is Saturn, in almost the same quarter of the sky—I'll move to the telescope….
"Hello! It looks like some kind of building—completely black—quite hard to see. No windows or any other features. Just a big, vertical slab—it must be at least a mile high to be visible from this distance. It reminds me—of course! It's just like the thing you found on the Moon! This is TMA-1's big brother!"
Chapter 37
Experiment
Call it the Star Gate.
For three million years, it had circled Saturn, waiting for a moment of destiny that might never come. In its making, a moon had been shattered, and the debris of its creation orbited still.
Now the long wait was ending. On yet another world, intelligence had been born and was escaping from its planetary cradle. An ancient experiment was about to reach its climax.
Those who had begun that experiment, so long ago, had not been men—or even remotely human. But they were flesh and blood, and when they looked out across the deeps of space, they had felt awe, and wonder, and loneliness. As soon as they possessed the power, they set forth for the stars.
In their explorations, they encountered life in many forms, and watched the workings of evolution on a thousand worlds. They saw how often the first faint sparks of intelligence flickered and died in the cosmic night.
And because, in all the galaxy, they had found nothing more precious than Mind, they encouraged its dawning everywhere. They became farmers in the fields of stars; they sowed, and sometimes they reaped.
And sometimes, dispassionately, they had to weed.
The great dinosaurs had long since perished when the survey ship entered the Solar System after a voyage that had already lasted a thousand years. It swept past the frozen outer planets, paused briefly above the deserts of dying Mars, and presently looked down on Earth.
Spread out beneath them, the explorers saw a world swarming with life. For years they studied, collected, catalogued. When they had learned all that they could, they began to modify. They tinkered with the destiny of many species, on land and in the ocean. But which of their experiments would succeed they could not know for at least a million years.
They were patient, but they were not yet immortal. There was so much to do in this universe of a hundred billion suns, and other worlds were calling. So they set out once more into the abyss, knowing that they would never come this way again.
Nor was there any need. The servants they had left behind would do the rest.
On Earth, the glaciers came and went, while above them the changeless Moon still carried its secret. With a yet slower rhythm than the polar ice, the tides of civilization ebbed and flowed across the galaxy. Strange and beautiful and terrible empires rose and fell, and passed on their knowledge to their successors. Earth was not forgotten, but another visit would serve little purpose. It was one of a million silent worlds, few of which would ever speak.
And now, out among the stars, evolution was driving toward new goals. The first explorers of Earth had long since come to the limits of flesh and blood; as soon as their machines were better than their bodies, it was time to move. First their brains, and then their thoughts alone, they transferred into shining new homes of metal and of plastic.
In these, they roamed
among the stars. They no longer built spaceships. They were spaceships.
But the age of the Machine-entities swiftly passed. In their ceaseless experimenting, they had learned to store knowledge in the structure of space itself, and to preserve their thoughts for eternity in frozen lattices of light. They could become creatures of radiation, free at last from the tyranny of matter.
Into pure energy, therefore, they presently transformed themselves; and on a thousand worlds, the empty shells they had discarded twitched for a while in a mindless dance of death, then crumbled into rust.
Now they were lords of the galaxy, and beyond the reach of time. They could rove at will among the stars, and sink like a subtle mist through the very interstices of space. But despite their godlike powers, they had not wholly forgotten their origin, in the warm slime of a vanished sea.
And they still watched over the experiments their ancestors had started, so long ago.
Chapter 38
The Sentinel
The air in the ship is getting quite foul, and I have a headache most of the time. There's still plenty of oxygen, but the purifiers never really cleaned up all the messes after the liquids aboard started boiling into vacuum. When things get too bad, I go down into the garage and bleed off some pure oxygen from the pods. . . .
"There's been no reaction to any of my signals, and because of my orbital inclination, I'm getting slowly farther and farther away from TMA-2. Incidentally, the name you've given it is doubly inappropriate—there's still no trace of a magnetic field.