The Stone was still active, even though these chambers had been deserted centuries before.

Lanier hadn't answered many questions, telling her it was "the process" to let her see and experience the Stone, step by step. "Otherwise," he had said, "why should you believe what we tell you?" That made sense, but she was still frustrated. What was so mysterious? The Stone was magnificent and startling, but not—so far as she could tell—anything to arouse her professional interest. Straightforward physics, however advanced.

It was simple, really. Take one large asteroid, rock with a core of nickel-iron—your average billennia-old chunk of primordial planet-stuff—and push it into an orbit around your planet. Hollow out seven chambers, each connected by an axial bore hole, then worm-hole some of the remaining volume with tunnels, accessways, storage depots and elevators. Bring up supplementary carbonaceous and ice-volatiles asteroids and begin transferring their material into the chambers. Send it on a journey into deepest space, and voila!

The Stone.

She had learned a few key facts so far. Each chamber floor was connected by tunnels dug through the intervening asteroid material. Many of the tunnels were part of an extensive train transport system. There were no trains in the first chamber because it had served as a reserve and storage area and had been infrequently visited in the time when the Stone was populated. The seventh chamber had apparently served a similar purpose, which made sense—the outermost chambers doing double duty as buffers against damage to the comparatively thin ends of the asteroid. The wall between the first chamber cap and space was only a few kilometers thick in places.

But there was something peculiar about the seventh chamber. She had felt it in Lanier's voice and seen it in the expressions of those she had met in the cafeteria. And there had been the rumors on Earth. . .

Somehow, the seventh chamber was different, important.

She had met five team scientists so far, three in the cafeteria: Robert Smith, tall and bird-boned with red hair and down-angled eyes that made him seem sad, an expert on asteroid formation; Hua Ling, the slender and intense senior member of the Chinese team and a plasma physicist who spent most of his time at the south polar bore hole; and Lenore Carrolson, a round-faced woman of fifty with gray-blond hair and a permanently friendly, sensual expression, heavy-lidded eyes surrounded by smile lines.

Carrolson had greeted Patricia with motherly solicitude. It had taken Patricia several minutes to realize that this was the Lenore Carrolson, Nobel laureate, the astrophysicist who had discovered and partly explained gemstars eight years before.

Carrolson had taken Lanier's hint that it was her duty to show Patricia the women's quarters in the compound. They were in a long, fiberwall barracks on the north end of the quadrangle. The rooms were small and spare but comfortable in their own ingenious ways, everything lightweight and compact. In the building's lounge, Carrolson had introduced her to two other astronomers, Janice Polk and Beryl Wallace, both from the Abell Array in Nevada. They sprawled on couches that looked as if they had been assembled out of scrap metal in a high school shop class. Polk resembled a fashion model more than Patricia's image of an astronomer. Even in a jumpsuit, her dark beauty was elegant and distant, her expression not so much disapproving as skeptical. Wallace was attractive enough, but about twenty pounds overweight. She seemed perturbed about something.