Imperial Earth

To the bitter disappointment of the exobiologists, they had turned out to be a purely natural phenomenon-the equivalent, at a much lower temperature, of terrestrial lava tubes. The head of a wax worm moved, judging from the seismic records, at up to fifty kilometers an hour, preferring slopes of not more than ten degrees. They had even been known to go uphill for short distances, when the driving pressure was sufficiently high. Once the core of hot petrochemicals had passed along, what remained was a hollow tube as much as five meters in diameter. Waxworms were among Titan’s more benign manifestations; not only were they a valuable source of raw materials, but they could be readily adapted for storage space and even temporary surface housing-if

one could get used to the rich orchestration of alliphatic smells. The hover sled had another reason for speed; it was the season of eclipses.

Twice every Saturnian year, around the equinoxes, the sun would vanish behind the invisible bulk of the planet for up to six hours at a time.

There would be no slow waning of light, as on Earth; with shocking abruptness, the monstrous shadow of Saturn would sweep across Titan, bringing sudden and unexpected night to any traveler who had been foolish enough not to check his calendar.

Today’s eclipse was due in just over an hour, which, unless they ran into obstacles, would give ample time to reach the wax worm The sled was now driving down a narrow valley flanked by beautiful ammonia cliffs, tinted every possible shade of blue from the palest sapphire to deep indigo. Titan had been called the most colorful world in the Solar System-not excluding

Earth; if the sunlight had been more powerful, it would have been positively garish. Although reds and oranges predominated, every part of the spectrum was available somewhere, though seldom for long in the same place. The methane storms and ammonia rains were continually sculpting the landscape.

“Hello, Sled Three,” said Oasis Control suddenly. “You’ll be out in the open again in five kilometers less than two minutes at your present speed.

Then there’s a ten-kilometer slope up to the Amundsen Glacier. From there, you should be able to see the worm. But I think you’re too late-it’s almost reached World’s End.”

“Damn,” said the geologist who had been handling the sled with such effortless skill. “I was afraid of that. Something tells me I’m never going to catch a worm on the run.”

He cut the speed abruptly as a flurry of snow reduced visibility almost to zero, and for a few minutes they were navigating on radar alone through a shining white mist. A film of sticky hydrocarbon slush started to build up on the forward windows, and would soon have covered them completely if the driver had not taken remedial action A high-pitched whine filled the cabin as the sheets of tough plastic started to oscillate at near ultrasonic frequencies, and a fascinating

pat53 tern of standing waves appeared before the obscuring layer was flicked away.

Then they were through the little storm, and the jet-black wall of the

Amundsen Glacier was visible on the horizon. In a few centuries that creeping mountain would reach Oasis, and it would be necessary to do something about it. During the years of summer, the viscosity of the carbon-impregnated oils and waxes became low enough for the glacier to advance at the breath-taking speed of several centimeters an hour, but during the long winter it was as motionless as rock.

Ages ago, local heating had melted part of the glacier and formed Lake

Tuonela, almost as Stygian black as its parent but decorated by great whorls and loops where lighter material had been caught in patterns of turbulence, now frozen for eternity. Everyone who saw the phenomenon from the air for the first time thought he was being original when he exclaimed:

“Why, it looks exactly like a cup of coffee, just after you’ve stirred in the cream!”

As the sled raced over the lake, the pattern flickered past in a few minutes, too close for its swirls to be properly observed. Then there was another long slope, dotted with large boulders which could be avoided only by the full thrust of the under jets This cut speed to less than a hundred klicks, and the sled labored up toward the crest in zigs and zags, the driver cursing and looking every few seconds at his watch.

“There it is!” Duncan shouted.

Only a few kilometers away, coming out of the mist that always enveloped the flanks of Mount Shackelton, was a thin white line, like a piece of rope laid across the landscape. It stretched away downhill until it disappeared over the horizon, and the driver swung the sled around to follow its track.

But Duncan already knew that they were too late to achieve their main objective; they were much too close to World’s End. Minutes later, they were there, and the sled came to a stop at a respectful distance.