“Suppose I told you it might cost us our lives.” He grinned tightly. “In fact, probably. That’s the part I’ve been sleeping on.”

She closed her eyes. “I guess we’re all soldiers now,” she said. “And this is the front line.”

“Suppose I told you it will certainly cost Arkady his life.”

She kept her face still. “Why?”

“We talked about this. Because somehow Arkady is going to have to deliver that nuke of his to the surface, at the South Pole. It’s kind of hard to see how he can do that without at least stranding himself in orbit. Look, Geena, when I came out here I didn’t know what Arkady meant to you.”

“Would that make a difference now?”

“I don’t know,” he said. “Let’s face it. It’s complicated.”

“Then we must ask Arkady how he feels.”

“Yes,” he said. “Yes, we must.”

“Tell me what you got.”

He opened up his laptop, and started to explain.

And that was how it started.

They got into a complex four-way discussion, involving Houston, Korolyov, Arkady up in orbit, the two of them huddled in their shelter.

The mission planners in Moscow and Houston came up with a way for Arkady to deliver the bomb as Henry asked. It was actually Arkady’s idea. They chewed it over from every which way.

It lasted hours. It involved geologists, orbital mechanics specialists, NASA managers, even politicians.

The plan was wild, implausible, resting on a lot of unproven assumptions. And none of them — Arkady, Geena or Henry — had a hope of living through it, to see if it worked.

But, she slowly realized, they were going to do it anyhow.

Eventually they got the go-ahead. The consensus was, they had little, after all, to lose by trying Henry’s outrageous idea.

Arkady, of course, agreed immediately, as Geena knew he would.

When she thought about it, his proposal was entirely in line with his character. Because it would allow him to become a hero at last: a new Gagarin, transcending the old, the saviour of the planet.

And as they talked on, the sun climbed imperceptibly into the sky, and the slow lunar morning wore on towards its long noon.

5

The procedures for the final operation were rather intricate. Arkady copied them down by hand, on the backs of checklists for the trans-Earth injection burn and Earth-return aerobraking manoeuvre, neither of which would be required now. And when he had transcribed them he read them back to the ground controllers, in English and Russian.

He was forced to perform a brief space walk.

He opened the forward hatch, in the nose of the Soyuz’s orbital module, and thrust his head and shoulders into space. Then he clambered out, hauling the laser package after him.