“Let ’er fly,” Carl said.

He felt it through his boots. A trembling, a gathering rush, a sudden trembling release. From the muzzle of Launcher 16 came…nothing he could see. But he could feel each slug of coated iron flee down the electromagnetic gun, fevered pulses shaking the slender tube. Machine gun aimed at the stars. Against the black oblivion above they made no mark, merely arced into its nothingness.

It was a feather’s brush against a boulder, but over time the effects would mount up.

He turned to look down the row. Each launcher flung its shots steadily skyward, the electromagnetic fringe fields sounding as a faint but persistent rata-rata-rata-rata over the comm line.

He should call JonVon, he knew, put the picture on all TV monitors, alert the crew. But for the moment he paused and savored it for himself.

They were heading back, now. Homeward. Halley’s slow sluggish orbit would blunt, turn, warp. For better or worse, they would glide down the gravity mountain, toward a destiny they could not see. It was an end to their long, inert obedience to gravity’s rule. Halley had become a ship.

—At last we’re doin’ somethin’! —Jeffers called.

Carl shouted in sudden joy, all doubts banished. “Sun, here we come!”

He stared at the crack in the wall. The black opening snaked far back into the ice. “When did this happen?” Saul asked.

Two of his assistants—brown-haired, with identical patterns of freckles on their faces—looked up from a lab bench nearby where they had been working. They answered together, in the same tones.

“There was a Halley quake, Pops,” they said in unison. “Two hours ago. A big one. It split the wall.”

“It certainly did,” he said, examining the damage. This would have to be attended to. Even this deep below the surface, it was foolish to let any chamber remain unsealable for long.

Some said it was the flinger launchers, stressing the comet core as they pushed it month by month, year by year, that were causing the quakes. Others blamed the war, now apparently lost for good by Quiverian and his Arcists.

Last month, Carl’s spacers, Sergeov’s Ubers, and Keoki Anuenue’s neutrals had joined together in a lightning raid on the Arcists’ south-pole redoubts, and permanently crippled the remnants of the first set of flingers, and the hidden microwave antennas with which they had been talking to Earth. One result was that now the Arcists could no longer use those old launchers to interfere with the Nudge toward Mars. Unfortunately, during that brief but bloody skirmish, three explosions had rocked that end of Halley Core, worrying some that the integrity of the comet itself might be threatened.

Whatever the cause, the quakes bothered Saul. For four years, now, things had been going well for a change. They had picked up word from Earth’s faint data net that the odds makers were once more taking bets on the colony’s survival. The current rate was five to one against. But that was a vast improvement over the thousand-to-one betting when he and Virginia had awakened from their thirty-year sleep.

For now, at least, Sergeov’s Ubers, the various clans of survivors, and Jeffers’s Mars Boys were all working together. But the alliance struck Saul as being like a supersaturated solution of immiscible fluids—too unsteady to last for long.

They didn’t need these Halley quakes shaking up the delicate balance.

Saul was dressed in little more than a loincloth, robe, and ice-sandals, as he had only left the quarters he shared with Virginia for a brief visit to his lab. She had gone up to the surface to talk something over with Carl Osborn, so he had taken the opportunity to come down here and see how the experiments were going.

Everywhere in the lab there were glassed-in chambers, like aquaria, in which mini-ecosystems flourished or languished—where modified Earth lifeforms struggled to prove themselves worthy of inclusion in the new, synthetic cometary ecology that was only now starting to sort itself out.

Over by the left wall, some of his assistants tended the animals…birds without feathers and goats able to give milk in microgravity.

“Where is Paul?” he asked suddenly.

The brown-haired twins nodded toward the crack in the wall, and shrugged.

“What?” Saul blinked. “I thought I told you to keep him here!”

They rolled their eyes in an expression he had seen countless times, over many mirrored years. “You told us not to let him out the door,” they reminded him smugly.

“Oh Lord.” Saul sagged. Was I ever like these two? So insufferably… immature?

They giggled together. Saul hesitated. He had to go after Paul, of course. The poor child might be the size of a full-grown man, but he wouldn’t be able to take care of himself out there alone.

I can’t take any of the kids with me, he realized, dismissing the idea of putting together a search party of his assistants. They’d scare the hell out of people by emerging out in the halls in a swarm. He had not introduced them to anybody else yet, not even Virginia. They were the most amazing development to come out of the union of Phobos technologies and his growing skill at clone-symbiosis, but this time he wasn’t sure at all how to let the rest of the colony know about them.

Saul lope-floated over to the hole in the wall. He picked up a glow-ball of gene-designed Halleyvirid phosphor. “When I get back we’re going to have a talk about responsibility,” he warned them. “Paul is still your brother even if he’s deficient in some ways. It was your duty to take care of him.”

They looked down, shamefaced. They weren’t bad kids, just inexperienced—very new to the world.

Two whirling, black sticks of fur leaped onto Saul, clambering over his shoulders. He gently unpeeled the midget gibbons.

“Not now, Max, Sylvie. I’ll be right back. Stay with the boys.” They stared after him, wide-eyed, as Saul turned and dove into the dark gap alone.

Of course Paul probably wasn’t in any danger. He was immune to purple toxins, of course, and if this passage held air, so did everything connected to it.

If only I can catch up with him before he runs into people.

Sooner or later, of course, he would have to reveal what he was doing. Announce that he had finally found solutions to many of the problems of growth and development that had made child-rearing a near impossibility on Halley.

What he had learned might even be applied to helping the thirty or so children the Orthos and a few Percells had already produced. During the last year, improving the lot of those poor, warped creatures had been one of his highest priorities.

He had hoped to put off showing people his own “kids,” though, until the Nudge was fully under way and people were filing back into the slots. It might go over better when there were fewer people around.

I hope I can catch Paul in time. Strangers might upset him.

In the soft light given off by the glow-ball, the crevice in the ice was a sparkling wonderworks of jagged crystals and puffy clathrate snow. It was easy to follow the path the youngster had taken by the handholds he had used. A smudge here, there a thread ripped from the floppy old lab coat Paul liked to wear. Saul followed the trail through a small crystal chamber that had not been charted before, now exposed in all its agate glory by recent tremors in the ancient ice.