2001_ A Space Odyssey - Arthur C. Clarke [70]
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