The beautiful ice cave was abandoned. It wouldn't be able to withstand the stress of two gravities. More tunnels were dug through the ice; new homes, made hemispherical for maximum strength, were hollowed out. The colonists strung lights everywhere, but even so Gage found their new warren-world gloomy, claustrophobic. She felt her spirits sinking.

The drives were ramped up to two gee in a day.

Only the strongest could walk unaided. The rest needed sticks, or wheelchairs. Broken bones, failing knees and ankles, were commonplace. Those like Gage who'd grown up on low-gravity worlds, or in freefall, suffered the most. The improvised AS units were forced to cope with a plague of failing hearts and sluggish circulations.

It was like growing old, in twenty-four hours.

Gage and Moro attempted sex, but it was impossible. Neither could support the weight of the other's body. Even lying side by side, facing each other, was unbearable after a few minutes. They touched each other tenderly, then lay on their backs in Moro's cavern, holding hands.

After three more months Maris Mackenzie came to see Gage. Mackenzie used a wheelchair; her large, fragile, beautiful bald head lolled against the back of the chair, as if the muscles in her neck had been cut.

"The missile is changing again," Mackenzie said. "It's still maintaining its two-gee profile, but its drive is flaring spasmodically. We think it's redesigning its drive; it's going to move soon to higher accelerations still. Much higher."

Gage lay on her pallet; she felt as if she could feel every wrinkle in the ice world under her aching back. "You can't be surprised. It was just a question of time."

"No." Mackenzie smiled weakly. "I guess I've screwed us up. We could have just stayed in our quiet orbit between Saturn and Uranus, not bothering anybody, flying around in that beautiful freefall ice cavern."

"The Squeem would have found us eventually."

"We're using up so much of our water. It breaks my heart. My beautiful ocean, thrown away into space, wasted. But we can go faster. We can still outrun the damn thing."

Gage knew that was true.

Once GUTenergy had fueled the expansion of the Universe itself. In the heart of each GUTdrive Chiron ice was compressed to conditions resembling the initial singularity -- the Big Bang. The fundamental forces governing the structure of matter merged into a single, Grand-Unified-Theory superforce. When the matter was allowed to expand again, the phase energy of the decomposing superforce, released like heat from condensing steam, was used to expel Chiron matter in a rocket action.

But none of that made a difference.

Gage sighed. "We've already abandoned half our tunnels because of tiny gradients we didn't even notice under one gee. We're slowly dying, under two gee, despite the AS units. We can't take anymore. I guess this latest maneuver of the missile will be the end for us."