There were few children.

The people of Kasyapa were welcoming, but she found they were locked into tight family groups. She would always be an outsider here.

Madeleine spent a lot of time alone, cooped up in her ice-walled box. She engaged in peculiar time-delayed conversations with Nemoto; with a minimum of ten hours between comment and reply, it was more like receiving mail. Still, they spoke. And gradually Nemoto revealed the deeper purpose she had concocted for Madeleine.

“These people are starving,” Nemoto whispered. “And yet they are sitting on a frozen ocean…”

Triton was, Nemoto told her, probably the Solar System’s most remote significant and accessible cache of water, within the Kuiper Belt anyhow. She said that Robert Goddard, the American rocketry pioneer, had proposed — in a paper called “The Last Migration” — that Triton could be used as an outfitting and launching post for interstellar expeditions. “That was in 1927,” Nemoto said.

“Goddard was a farsighted guy,” Madeleine murmured.

“…Even if he got it wrong,” Nemoto was saying — had said, ten hours earlier. “Even if, as it turns out, Triton will be used as a staging post for expeditions from the stars. And not used by us, but by ETs. The Gaijin.”

But the ocean under Madeleine’s feet, tens of kilometers thick, was useless for the colonists as long as it was frozen hard as rock.

“Imagine if we could melt that ocean,” Nemoto said, her face an expressionless mask.

But how? The Sun was too remote. Of course the sunlight could be collected, by mirrors or lenses. But how big would such a mirror have to be? Thousands of kilometers wide, more? Such a project seemed absurd.

“It’s not the way humans work,” Madeleine said gloomily. “Look at the colonists here, burrowing like ants. We’re small and weak. We have to take the worlds as they are given to us, not rebuild them.”

Nemoto’s reply came many hours later. “And yet, that is exactly what we must do if we are to prevail. We are going to have to act more like Gaijin than humans.”

Nemoto had a plan. It involved diverting a moon called Nereid, slamming it into Triton.

Madeleine was immediately outraged. This was arrogance indeed.

But she let Nemoto’s data finish downloading.

It was a remarkable, bold scheme. The rocket engines that had brought the colonists here would now be used to divert a moon. The numbers added up. It could be done, Madeleine realized reluctantly. It would take a year, no more.

It was also, Madeleine thought, quite insane. She pictured Nemoto, stranded centuries out of her time, isolated, skulking in corners of the Moon, concocting mad schemes to hurl outer-planet moons back and forth, an old woman fighting the alien invasion, single-handed.

And yet, and yet…

She looked inward. What is it I want?

All her family, the people she had grown up with, were lost in the past, on a frozen world. She was rootless. And yet she had no pull to join this tight community, had felt no envy of Ben when Lena had recaptured him, on his arrival here. Her life had become a series of episodes, as she’d drifted through scenes of a more-or-less incomprehensible history. Was it even possible to sustain a consistent motivation — to find something to want?

Yes, she realized. It isn’t necessary to be picaresque. Look at Nemoto. She still knows what she wants, the same as she always did, after all these years. Maybe the same applied to Reid Malenfant, wherever he was. And maybe that was why Madeleine was attracted to Nemoto’s projects — not for the worth of the work, but for Nemoto’s singular strength of mind.

She went to discuss it with Ben. His first reaction was like hers.

“What you’re proposing is barbaric,” Ben said. “You talk of smashing one moon into another. You will destroy both.”

“It’s technically feasible. Nemoto’s numbers prove that a deflection of Nereid by the thruster systems from the orbiting transports would—”

“I’m not talking about feasibility. Many things are feasible. That doesn’t make them right. Once Triton is changed, it is changed forever. Who knows what future, wiser generations might have made of these resources we expend so carelessly?”

“But the Gaijin are on their way now.”

“We wreck this world, or they do. Is that the choice you offer?”

“Triton is ours to wreck, not theirs!”

He considered. “I will concede your plan has one positive outcome,” he said at length.

“What?”

“We are barely surviving here. The Yolgnu. That much is obvious. Perhaps with what you intend—”

She nodded. “It will work, Ben.”

“There will be a lot of opposition. People have been living here for generations. This is their home. As it is.”

“I know. It’s going to be hard for all of us.”

“What will you do now?”

She considered. She hadn’t thought it through that far. “We can send probes to Nereid,” she said. “Survey the emplacements of the thrust units, perhaps even initiate the work. Ben, those Gaijin are on their way, whatever we do. If we leave this too long we might not be able to do anything anyhow.” She squinted up at the ice roof, imagining the abandoned ships circling overhead. “We could even begin the deflection, start the thrusters. It will take a year of steady burning to set up the collision. But I’ll initiate nothing irrevocable until you get agreement from your people.”

“You started out your career as a transporter of weapons,” he said sadly. “And you are still transporting weapons.”

That irritated her. “Look, Triton is a lifeless planet. There is nothing here but humans, and what we brought.”

He eyed her. “Are you sure?”

After a couple of months, to Madeleine’s surprise, Lena Roach invited her to “go walkabout,” as she called it, to go see something more of Triton.

Madeleine was a little suspicious. She remained the focus of the colony’s intense debate about its future; few people were so open with her that such offers didn’t come with strings.

She spoke to Ben.

He laughed. “Well, you’re right. Everybody’s got a point of view. Lena has her opinion. But what harm can it do to go out and see some ice?”

Madeleine thought it over for a day.

The Nereid project had begun. Ben had loaned her Kasyapa engineers to detach the engine units from the transport hulks in orbit around Triton, reconfigure them for operation on Nereid, improvise systems to extract fuel from the substance of the moon. She had a small monitoring station set up in her ice cell that showed her, by telemetry and a visual feed, that sparse array of engines burning, twenty-four hours a day, consuming Nereid’s own material as fuel and reaction propellant, slowly, slowly pushing the battered moon out of its looping ellipse. It was good to have a project, to be able to immerse herself in engineering detail.

But she would have a year to wait, even if Kasyapa’s great debate concluded in an acceptance of her program. Ben, torn between his lost family and the endless work of the colony, had little time to spend with her. There were few people here, nowhere to escape, little to do. She still spent much of her time alone, in her ice cell, immersed in virtuals, reading up on the dismal history she had skipped over.

Getting out of here would be a good thing. She agreed to go along with Lena.

So they climbed aboard a surface tractor, a big balloon-tire bubble.

At first they drove in silence, the tractor bouncing gently. Madeleine felt as if she were floating, all but naked, above Triton’s icy ground. The sky was a velvet dome crowded with stars, and with that subtle, misty hull of Neptune riding at the zenith above their heads.

Lena was a small, compact woman, her movements patient and precise. She had been just twenty when Ben had departed for the Saddle Point. Her age was over a hundred and twenty years old, but, thanks to rejuvenation treatments, she might have been forty. But she didn’t act forty, Madeleine thought; she acted old.