Michael stared at the sphere, which was fast becoming a giant wall below them. "Decel burn," said the marine. Michael held on as weight reappeared for a second. Then they were drifting ever so gently in the direction of that dangling cable.

People from the other cart were grabbing for the line; Michael hardly noticed. He couldn't take his eyes off the sphere. He did not need the NeoShinto AI to help him feel awe of this place.

He imagined diminutive Rue Cassels floating here with her companions. Just them— alone, unknown to the rest of humanity and about to open an inhuman door. His admiration for her kept growing.

"Go, Corinna," said Rue. One of the anonymous space suits began to pull itself hand over hand up the line. Corinna stopped at a broad disk of ribbed and spikey, slightly purple material and began digging at an indentation near its edge.

"The airlock's a magnetic liquid; right now it's frozen so the magnets aren't on," said Corinna. "This switch turns on the heat and magnets at the same time. Watch." She withdrew her hand and the purple surface suddenly roiled and shimmered like an oil slick. Corinna reached over and her arm disappeared up to the shoulder in the material. "See?"

"Wait for us," said the lead marine. Both carts were at the cable now and Michael watched as they reeled themselves in.

"What's fun," said Rue, "is that the air pressure inside wants to pop you out like a grape seed. It's easier to get out than in, which doesn't strike me as too safe."

"On the other hand," said Dr. Herat, "there's no moving parts."

They were clustered around the disk now. "There's a bar just inside the edge here," said Corinna. "Just grab and do a flip— like so." She reached into the disk, somersaulted, and disappeared into it. The marines followed.

The material of the disk was denser than Michael expected— almost a meter thick and lens-shaped. It resisted his passage like a strong wind. When he completed his roll, though, he found himself floating inside a cylinder about four meters long and three across. It was brightly lit by the marines' floodlights and lined with ordinary-looking rectangular locker doors.

"You inspected these?" Herat pointed at them.

"Yeah," said Rue. "Nothing in them. Spotlessly clean, too. Like they'd never been used." She was undogging her helmet. "It's just nitrogen in here, so monitor your mesobots to make sure you don't come down with nitrogen narcosis. And keep your nosepiece in." She demonstrated the oxy clips, which promptly made her sound congested. Michael pulled up an inscape readout to watch the nitrogen scrubbers in his own bloodstream. He situated it down and to the right in his peripheral vision, so it wouldn't get in the way.

"Next is the strap palace," said Rue. She was obviously enjoying playing tour guide. "Come along, don't dawdle."

The far end of the cylinder had a two meter-wide opening in it. This turned out to be the entrance to a long round corridor. As Rue's name for it implied, the corridor was strung with hundreds of rubbery straps, each as wide as Michael's waist. They crisscrossed the space at various angles, making it impossible to see down the length of the cylinder.

"This is bizarre," said Katz unnecessarily. "What the hell are these things?"

Herat said, "I'd say the logical equivalent of handholds or steps, for something that uses its whole body for locomotion. Bequith?"

His scalp crawled looking at the things. "Maybe." Rue was hauling herself from strap to strap, closely followed by the two marines. The lights cast weird tongues of shadow across everything.

"This is like nothing I've ever seen," said Katz.

"But we can infer a lot from it," said Herat. "They were less than two meters in diameter, probably not more than three long; look, if you were a fish or an eel, you'd be able to bounce your way along this corridor pretty quickly. If it were completely open, you'd be whacking the walls or adrift— there'd be nothing for your body to undulate against."

"You think they're fish?"

"Why not? After all, everything below here seems to be full of some kind of liquid."

The corridor ended in a large long space Michael recognized from photographs as the shore of Lake Flaccid. It was spookier in real life: a long cylinder, like a cave or tunnel, lit only by darting flashlight beams, with darkness at its far end. Rue had overshot her landing and now hung in the very center of the space. She was fiddling with her wrist rockets, trying to jet back. In freefall, up and down were arbitrary choices; Michael could choose to think he was looking down a wide deep well, but it was more comforting to choose one side of that well and decide that it was «down» and that the side opposite it was "up." Indeed, in unspoken agreement everyone drifted over to one wall and oriented their feet down to it. Michael did the same and now he could imagine the cylinder was lying on its side and he and the others were standing inside it.

"Strange. What are these?" Katz's voice made no echoes here. He was shining his lamp at some translucent circles set in the floor. "Lights?"

"That's what we thought," said Corinna. She took a tiptoe step and sailed over to one. "But they're gelatinous and have things embedded in them. Like a jelly salad."

Katz joined her. "It's dark stuff, different shapes and sizes. Looks like… peas… and something cylindrical… and a square block. Can't be a light."

Herat dismissed the circles with a wave of his hand. "Signs. Actually," he said, looking around, "this place is festooned with writing. It's just that it's for beings who see with sonar."

Everybody turned to stare at Herat. Michael hid a smile; the professor was showing off, but he had to admit it was impressive. Herat's ability to look at an alien artifact and determine its purpose was legendary. These scientists were seeing that ability in action for the first time.

"Let's see what this lake is made of, shall we?" Dr. Herat folded himself cross-legged and gradually drifted down to rest on the lip above the gray substance Rue had called a lake. Michael wouldn't have known that the gray stuff wasn't solid if he hadn't been briefed. It simply looked like the ends of the cylinder were metal and the slightly wider middle part was this gray material. It was hard for the planet-born to imagine a cylindrical pool, after all; the lake was below him, but it also curved up to each side and was overhead. Reason told him that because the habitat rotated, the liquid would move outward because of centrifugal force. It was much easier just to ignore the liquid above him and see only what was below.

One of the scientists, Dr. Salas, was a materials specialist. He hunkered down with Dr. Herat and they dipped things in the lake for a while, talking in low murmurs, sometimes laughing. One of the marines had unpacked some fish-shaped mesobots and now held one over the lake; its sonar was able to penetrate the strange surface with ease. Michael opened an inscape view of the sonar signal and got his first view of the bottom of the lake.

Evan Laurel saw the inscape window and drifted over. "Stuff conducts sound really well." He pointed out a feature in their shared window. "Hey, that looks like an armchair…. Except it's a good four meters across."

"There are openings in the walls," said the marine.

"Yeah. We figured we'd make some of those our first target. Gravity gets pretty steep as you go down. At the bottom it's twice Earth-standard."

The other marine had drifted out across the lake and was inspecting the far end.

Dr. Herat began to laugh. "Of course! It's a perfect solution!"

They all clustered around him. He grinned, holding up a jar full of grayish stuff. "It's not a liquid at all! It's actually made of fine little beads, a bit bigger than sand grains. It's a granulated aerogel!"