The bank of GUTdrive pods had opened up, raising Chiron’s acceleration to a full gee, to match the missile.

If Mackenzie’s analysis was correct, Chiron couldn’t outrun the missile, and the missile couldn’t overtake Chiron. It was a stalemate.

Gage stroked the muscles of Moro’s chest. “It’s actually a neat solution by the Squeem,” she murmured. “The pursuit will take years to play out, but the missile must catch us in the end.”

Moro pushed himself away from her, rolled onto his front, and cupped her chin in his hands. “You’re too pessimistic. We’re going to the stars.”

“No. Just realistic. What happens when we get to Tau Ceti? We won’t be able to decelerate, or the missile will catch us. Although we may survive for years, the Squeem have destroyed us.”

Moro wriggled on the floor, rubbing elbows which already looked sore from supporting his weight in the new thrust regime. He pulled at his lip, troubled.

Gage let herself get pregnant by Moro. The zygote was frozen, placed with a small store of others.

It was only after the storage of her zygote that Gage questioned her own motives in conceiving. How long was she expecting to be here? What kind of future did she think any of them could hope for?

Six months later the missile increased its acceleration to two gee.

The Squeem had been smart, Gage decided; they’d given the missile the ability to redesign itself in flight.

The colonists held another meeting to decide what to do. This time they sat around on the bare floor of their darkened ice cave; their elegant zero-gee amphitheater was suspended, uselessly, high on one wall of the cave.

Some wanted to stand and fight. But they had nothing to fight with. And Chiron, with its cargo of humanity, must be much more fragile than the hardened missile.

A few wanted to give up. They were still only fifty light days from the Sun. Maybe they could surrender, and return to the occupied worlds.

But most couldn’t stand the idea; it would be better to die. Anyway, a semisentient Squeem missile was unlikely to take prisoners.

They voted to run, at two gee.

They had to rebuild their colony again. Drone robots crawled over the battered surface of the ice world, hauling water-ice to the GUTdrive engines. Shields billowed wings of electromagnetic flux around the ice dwarf; they would soon be running at close to light-speed, and the thin stuff between the stars would hit Chiron like a wall.

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.”

“Not necessarily,” Mackenzie said. “I have another idea.” Gage turned her head slowly; she had to treat her skull as delicately as a china vase. “Your last one was a doozie. What now?”

“Downloading.”

It wasn’t a universally popular option. On the other hand, the alternative was death.

Eighty chose to survive, as best they could.

When her turn came Gage made her way, alone, to the modified AS machine at the heart of their warren of tunnels. The robot surgeon delicately implanted a sensor pad into her corpus callosum, the bridge of nervous tissue between the two hemispheres of her brain. It also, discreetly, pressed injection-pads against her upper arms.

All around her, in the improvised infirmary, people were dying, by choice.

So was Gage, if truth be told. All that would survive of her would be a copy, distinct from her.

The callosum sensor would download a copy of her consciousness in about eight hours. Gage returned to her cavern, lay on her back with a sigh, and fell asleep.

She opened her eyes.

She wasn’t hurting anymore. She was in zero gee. It felt delicious, like swimming in candy floss. She was in the ice cave — no, a Virtual reconstruction of the cave; the walls and house-stalks were just a little too smooth and regular. No doubt the realism of detail would return as their minds worked at this shared world.

Moro approached her; he’d resumed the crude disembodied-head Virtual form Gage had first encountered. “Hi.” He grinned.

“I just died.”

Moro shrugged. “Tell me about it. We’re all stored inside the shelter now.” This was a hardened radiation shelter they’d built hurriedly into the heart of the ice world; it contained a solid-state datastore to support their new Virtual existence, what was left of their vegetation, their precious clutch of human zygotes embedded in ice. “Our bodies have been pulped, the raw material stored in a tank inside the shelter.”

“You’ve a way with words.”

“…We’re up to a thousand gee,” Moro said.

Gage’s Virtual reflexes hadn’t quite cut in, so she made her mouth drop open. “A thousand?”

“That’s what the missile is demanding of us. All our tunnels have collapsed.”

“I never liked them anyway.”

“And the drones are having to strengthen the structure of Chiron itself; the thing wasn’t built for this, and could collapse under the stress.”