Titan

by John Varley

  "Whatever you say. Just a minute, I want to take off this shirt. I'm smothering."

  Cirocco stripped down, too, and they continued to hike through the furnace.

  Five hundred steps later, they put their clothes back on. Three hundred steps beyond that, they opened their packs and got out their coats.

  ice began to form on the walls, and snow crunched underfoot. They donned gloves and pulled up the hoods on their parkas, then stood in lamplight which had become amazingly bright with the white walls to reflect it, watching ice crystals condense from their breaths and looking forward at a corridor that was unquestionably narrowing.

  "A thousand more steps?" Gaby suggested. "You must have read my mind."

  The ice soon forced Cirocco to bend her head, then get on her hands and knees. It quickly grew dark again as Gaby led with the lamp in front of her. Cirocco paused and blew on her stiff hands, then got m her belly and crawled.

  "Hey! I'm stuck!" She was pleased to hear no panic in her voice. It was frightening, but she knew she could get free if she backed up.

  The scrabbling sounds in front of her stopped. "okay. I can't turn around here, but it's getting wider. I," go ahead and see what it's like. Twenty meters. Okay? "

  "Right." She listened to the sounds getting farther away. The darkness closed in and she had just enough time to work up a very cold sweat before the light dazzled her. In a moment Gaby was back. There were ice crystals on her eyebrows.

  "This is the worst spots right here." "Then I'll get through. I didn't come this far to end up like a cork in a bottle. "

  "It's what you get for eating all those sweets, fatty." Gaby could not pull her through, so she backed up and man- aged to get the brass pick from her pack. They chipped, at the ice and tried it again.

  "Breathe out," Gaby suggested. and tugged on her hands. She came through.

  Behind them, a flat chunk of ice about a meter long fell from the roof and skidded noisily toward daylight.

  "That must be why this passage is open," Gaby said. "The cable is flexible. It bends and the ice cracks."

  "That and the warm air from behind us. Let's stop plugging it up, okay? Get moving."

  Soon they could stand, and shortly afterward the ice was just a memory. They took off their coats and wondered what was next.

  The rumbling began 400 steps farther on. It grew louder until it was easy to imagine huge machines thrumming just beyond the walls of the tunnel. One of the walls was hot, but not any- thing like what they had already traveled through.

  They felt sure it was the sound of the air being sucked from the place of winds toward some unknown destination high above. Two thousand more steps brought them beyond it and into another hot region. They hurried through it, not bothering to strip as they knew they were close to the far end of the tunnel. As expected, the beat diminished after reaching a steam-bath peak that Cirocco estimated at seventy-five degrees.

  Gaby was still in the lead, and saw the light first. it was no brighter than it had been on the other side, just a pale silver strip that began on their left and gradually widened until they were standing on a ledge beside the cable. They slapped each other on the back, then started climbing again.

  They crossed over the top of the cable, always rising, always trending to the south, over the broad hump and down again on the far side. The cable was completely bare now; no trees, no earth clinging anywhere. It was the first time Gaea had really looked like the machine Cirocco knew it to be: the incredible, massive construct made by beings who might still be alive in the hub. The bare cable was smooth and straight, rising at an angle of sixty degrees now, getting closer to the flaring bottom edge of the spoke. The wedge of space between the cable and the spoke had narrowed to less than two kilometers.

  On the south side the stairs entered another tunnel. They thought they were ready for it, but it almost fooled them. They hurried through the first zone of heat and congratulated them- selves when they felt the temperature begin to drop again. It reached about fifty degrees, and began to rise once more.

  "Damn! It's a different set-up. Let's go!"

  "Which way?"

  "Back would be just as bad as forward. Move!"

  They would have been in danger only if one of them bad fallen and hurt herself, but it frightened Cirocco, and reminded her never to take Gaea for granted. She had forgotten the cable was made up of wound strands, and that the path of whatever hot and cold fluids ran through it could be quite complex.

  They made it past the zone of vibration which was still in the center, and through the cold zone, which was not as choked with ice as the first had been, and emerged once again on the north side of the cable.

  Across the top, and down into the third tunnel. Through it, and across the top again.

  They did that seven more times in two days. It would have been faster but for a delay in the fourth tunnel, which was so choked with ice even Gaby had to chip before she could squeeze through. it took them a frigid eight hours to break a path.

  But the next time they reached the south side of the cable,

  there was no tunnel. The angle of rise was now between eighty and ninety degrees, and the staircase began to wind along the outside of it like the red stripe on a peppermint stick.

  Neither wanted to camp on a ledge a meter and a half wide that hung over a drop of 250 kilometers. Cirocco knew she tossed in her sleep and one toss could carry entirely too far. So, though both of them were weary, they kept trudging around and around the outside of the cable, always pressing their left shoulders to the reassuring solidity.

  Cirocco did not like what was happening overhead. The nearer they got, the more impossible it looked.

  They knew from their observations outside that each spoke was oval in cross-section, fifty kilometers thick one way and slightly less than a hundred the other, before it flared out to join the rim roof. They had just passed thuough that flaring section, and the spoke walls they could dimly see were nearly vertical. What they had not counted on was the lip that ran all the way around the monstrous bore of the spoke tube. It was easily five kilometers wide.

  The cable seemed to enter the lip seamlessly, probably continuing above and traveling on to whatever tied it to the hub. During one of their rest stops they studied the lip, seemingly just above their heads, yet still two kilometers away. It was a massive ceiling to their labors, stretching endlessly until the opening became visible, narrowed by perspective. The opening was forty by eighty kilometers, but to reach it they would have to traverse five kilometers hanging from the underside of the lip.

  Gaby looked at Cirocco and raised one eyebrow. "Don't borrow trouble. Gaea's been good to us so far. Climb, my friend."

  And Gaea was good to them again. When they got to the top of the cable there was another tunnel, this one piercing the vast gray roof.

  They lit the lamp, noting that there was not much fuel left, and began to climb. The tunnel curved to the left as if the cable was still there, though they could no longer be sure of it. They counted 2000 steps, then 20M more.

  "It occurs to me," Gaby said, "that this could go all the way to the hub. And if you think that's good news, you'd better think against

  "I know, I know. Keep climbing." Cirocco was thinking of lamp fuel, the state of their provisions, and the half-filled water- skins. It was still 300 kilometers to the hub. At three steps to the meter, that made it almost an even million steps yet to go. She looked at her watch and timed their pacing.

  They had a rhythm of about two steps per second; just light touches of the toes to push them high enough to touch the next step. The gravity at that level had fallen to almost one eighth- half the already low gravity when they set out.

  Two steps per second was half a million seconds of travel time. Eight three three three point three, etc., minutes, 138 hours, or nearly six days. Double that to include rest periods and sleep, at a conservative estimate ...

  "I know what you're thinking," Gaby said, from behind her. "But
can we do it in the dark?"

  She had hit on the important point. The food could last two weeks. The water might be enough with rationing, but not for coming down.

  But the crucial consumable at this stage was lamp fuel. They had no more than a five-hour supply, and no way to get more.

  She was still working on it, trying to construct a mathematics that would get them to the top, when they emerged on the floor of the spoke.

  Nothing had ever made Cirocco feel smaller. Not O'Neil One, not the stars in space, not the floor of Gaea herself. She could see everything, and her sense of perspective failed utterly.

  It was impossible to detect the curvature of the walls. Like an upended horizon, they stretched away from her until suddenly they began to wrap around, making the space look more semi- circular than round.

  Everything was bathed in a pale green luminescence. The source of the light was four vertical rows of windows which sent beams slanting down to cross each other in the empty center.

  Not quite empty. Running straight as a ruler through the central space Were three vertical cables wound together like a braid, and drifting in and out of the light beams were odd, cylindrical clouds that twisted slowly as they watched.

  Cirocco recalled thinking of the dark, narrow spaces beneath the cable they had explored as a cathedral. Gaea had exhausted her store of superlatives, but she knew that had only been an abandoned chapel. This was the cathedral.

  "I thought I'd seen it all by now," Gaby said, quietly, pointing up at the wall behind them. "But a vertical jungle?"

  There was no other way to describe it. Clinging to the walls, reaching outward or branching up, the inside of the spoke was crusted with more of the ubiquitous trees. They dwindled, becoming at some indeterminate distance just a smooth carpet of green. Beyond that was a gray roof.

  "Would you say that's 300 kilometers up?"

  Gaby squinted, then made a grid with her fingers and calculated with some system of her own.

  "It covers the right number of degrees."

  "Sit. Let's think on this."

  She needed to sit more than she needed to think. Until this moment she had actually thought she could make it. She now saw that delusion had been fostered by an inability to visualize the problem. She could look at it now and she quailed inside. Three hundred kilometers, straight up.

  Straight. Up.

  She must have been insane.

  "First. Does it look like there's any way through that roof?" Gaby looked, and shrugged.

  "Means nothing. There was a way through this, wasn't there? Weld never see it from here."

  "Right. But we hoped there would be a ladder to the top. Do you see one?"

  "No."

  "Right again. I thought those stairs meant a way had been pro- vided to walk to the top, if necessary. Now I think it's likely that a walk to right here, this spot, was all the builders had in mind." "Maybe.' Gabys eyes had narrowed. "But they must have left

  way to get to the hub. Probably these trees weren't meant to be ere. They've overgrown everything, like they did on the cable." "In which case..." What?

  "We have a hell of a climb ahead," Gaby finished for her.

  "Right for the third time. I'm just trying to reason it out, you see. It had entered my mind that if-say four or five years from now-if we get to the top and find there isn't a stairway... we've got another long climb. Down."

  Gaby laughed this time.

  "If you're saying let's turn back, I wish you'd come out with it. I won't freeze you with contempt."

  "Let's turn back?" She hadn't meant the question mark, but there it was.

  "Ah. I see." She did not mind. They had long forgotten the relationship of Captain and crew. She laughed, and shook her head. "All right. What's your plan?"

  "First look around. Later-four or five years from now-we'd look pretty foolish if me of the builders asked why we didn't use the elevator."

  CHAPTER TWENTY-ONE

  It was roughly 250 kilometers around the base of the spoke. They began to circumnavigate it, looking for anything from a rope ladder to an anti-gravity helicopter. What they found was horizontal trees, growing in the vertical forest.

  When they penetrated the outer branches and followed the trunks to their roots in the wall, they had to climb a gradual slope made of fallen branches and rotting leaves. The real sub- stance of the spoke was a spongy gray material. It yielded like soft rubber when they pressed it. When Cirocco pulled a bush from the wall, a long taproot came out with it. The wall bled a thick, milky fluid, then closed around the small hole.

  There was no soil, and very little sun; bright as it had seemed when they came out of the dark staircase, the real light level was quite low. Cirocco assumed that, like many of the plants on the rim, these depended m sub-surface sources for life.

  The wall itself was moist and supported growths of moss and lichen, but few intermediate-sized plants. There were no grasses, and what vines existed were parasitic, rooting in the tree trunks. Many of the trees were the same species they had seen on the rim, adapted for a horizontal existence. There were familiar fruits and nuts growing on them.

  "That takes care of the food problem," Gaby said.

  There could be no rivers in the spoke, but the wall glistened with tiny trickles. High above, sports could be seen, arching out and turning to mist long before they reached the floor.

  Gaby looked up at them, noting that they seemed evenly distributed, like lawn sprinklers.

  "So much for dying of thirst."

  It began to seem that the climb would not actually be impossible. Cirocco found it hard to be elated about it.

  Excluding the possibility of a staircase-which she quickly concluded they would not find, since the trees prevented a close exploration of the wall-there were two ways to the top.

  One involved climbing the trees themselves. it should be possible, Cirocco reckoned, to go from branch to branch out where spreading had meshed the branches of one tree with those of its neighbors.

  The other possibility was a straightforward job of mountaineering. They found that their metal spikes could be driven into the wall surface simply by holding them and jabbing.

  Cirocco favored the wall, not wanting to trust the trees. Gaby liked the branches, which would be quicker. They debated it until the second day, when two things happened.

  Gaby noticed the first thing while looking ~ over the gray floor of the spoke. Her eyes narrowed, and she pointed.

  "I think that hole's not there anymore," she said. Cirocco squinted, but could not be sure. "Let's climb up and take a look."

  They roped themselves together and began ascending through the branches.

  It was not as bad as Cirocco had feared. Like anything else, there was an optimum way to go about it, and they quickly discovered what it was. There was a line to pick between the thicker branches closer to the wall-which were rock solid, but tended to be too far apart-and the thinner, more willowy ones farther out, which provided a thousand places for hands and feet but sagged under their weight. .

  "A little farther in," Cirocco called ahead to Gaby, who had taken the job of scouting the path at the end of a five-meter tether. "I'd say about two-thirds of the way to the top of the tree is about right."

  "In, top," Gaby said. "You're mi2dng your directions."

  "The bottoms of the trees are in close to the wall. The tops are out in the air. What could be simpler?"

  "Suits me."

  After climbing through ten trees they began to work their way out to the top of the last one.

  When the branches they walked on began to bend, they tied a line to a strong me. Now the sag worked to their advantage, as it opened a window in an otherwise impenetrable wall of foliage. They had chosen a tree that, in a horizontal forest, would have towered above its neighbors. In the spoke it had to be content with jutting further from the wall.

  "You were right. It's gone."

  "No I wasn't. But it will be in a minute."

&
nbsp; Cirocco saw what was left of the hole. It was a tiny black oval in the gray floor, and she could see it contracting like the iris of an eye. From below, the only time they had a good lock at it, that hole had been nearly as large as the spoke itself. Now it was less than ten kilometers across, and still closing. Soon it would seal around the vertical cables that emerged from its center.

  "Any ideas?" Gaby asked. "Mat good does it do to close the spoke off from the rim?"

  "I haven't the faintest idea. I presume it will open again, though, The angels got through it, they come through regularly, so it..." She paused, and then smiled.

  "It's the breath of Gaea."

  "Say again?"

  "It's what the Titaffides call the wind from the east. Oceanus brings cold weather and the Lament, and Rhea brings hot air and the angels. So you've got a tube 300 kilometers high, with a valve on each end. You could use it as a pump. You could create high and low pressure areas, and use them to move air."

  "How would you go about that?" Gaby asked.

  "I can think of two ways. Some kind of moveable piston to compress or rarefy the air. I don't see one, and I sure as hell hope there isn't or it'd smear us."

  "If there was, it wouldn't have done these trees any good."

  "Right. so it's the other method. The walls can expand or contract. Close the bottom valve and open the top one, expand the spoke, and you draw air in from the top. Close the top and open the bottom, put on the big squeeze, and you force it out over the rim."

  "Where does the air that comes in the top come from?"

  "It's either sucked up through the cables-some of it must be, we saw that-or it comes from the other spokes. They all connect at the top. With a few more valves, you can use the spokes against each other. Open and close a few, and you end up sucking air out of Oceanus, through the hub, and into this spoke. Then open and close some more, and force it down over Rhea. Now if I only knew why the builders thought it was necessary."

  Gaby looked thoughtful. "I think I can give you that. It's something that's bothered me. Why doesn't all the air pool at the botton down at the rim? The air's thinner up here, but it's still okay because the air pressure at the rim is higher than Earth-normal. And in low gravity, pressure sure drops off less quickly. Mars' atmosphere isn't much, for instance, but it goes out a long way. Then if you keep the air circulating, it doesn't have time to settle. You can keep adequate air pressure all the way through Gaea."