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.

The laser was an American Star Wars toy. Developed at Phillips Labs for the USAF, it was designed to be carried by a 747 aircraft, and used to shoot down short-range missiles. The technology was simple, light and robust, and no doubt inordinately expensive.

Still, the technology was remarkable. The laser was fuelled by hydrogen peroxide which was mixed with chlorine to produce oxygen atoms. At hypersonic speeds, the oxygen was forced with iodine into the lasing cavity, which was a container no bigger than a breadbox, with mirrors at either end. When the oxygen reacted with the iodine it emitted light which was bounced between the mirrors, before being released…

The power generated by this miniature contraption was more than a megawatt.

It had seemed absurd when Henry Meacher had requested this system. What was he expecting, dogfights with the Moonseed in orbit around the Moon? But now, it seemed, its true destiny was becoming clear.

It was a simple matter to fix the laser in place on the outer hull, with silver wire and tape, so that its blunt nozzle pointed ahead of the Soyuz. Arkady used his sextant to check its orientation; it must point directly along the axis of the craft.

When he closed the hatch and pressurized, he found the compartment filled with the sharp scent of space, the tang of scorched metal.

Next, he considered the nuclear weapon, the B61-11 bunker-buster, stowed here in the orbital compartment.

The laser could be controlled from a laptop computer, which he would have close to him during the landing. He ensured that the nuclear weapon could be triggered from the same device.

It was, thought Arkady, at heart a simple problem.

Henry insisted that his nuclear device, the bunker-buster, must be delivered to a precise point, at the very centre of the South Pole-Aitken Basin. But the nuclear device was in lunar orbit, on board Soyuz, and simply dropping it, at orbital speeds, would not suffice.

But to leave orbit and land took energy to remove the velocity with which a spacecraft circled the Moon. The two landers used in the mission had expended that energy in the form of rocket fuel.

Now there were no more landers available. And, just like the Apollo Command Module, Arkady’s Soyuz was not designed to land on the Moon.

Nevertheless, it had been decided, it would have to, in order to complete this new mission.

In the 1980s NASA had actually studied this mode of landing, if briefly. It opened up a new area of knowledge, tentatively called “harenodynamics’, which was a fancy Latin-derived term for “sliding’. Arkady had once attended a conference on lunar bases, industrialization and settlement, which had touched on the subject; when he raised it now with NASA’s Mission Control at Houston, it had not taken long for the back room people there to dig the material out of their archives.

And even less time to express their disbelief.

The trouble was, a Moon landing required a disproportionate amount of fuel. Because it had no air, either for frictional braking, or for supporting gliding or parachuting, the Moon gave its visitors no help on the way down.

But harenodynamics was a way of forcing the Moon to help after all. If it could be made to work, it could provide a way of landing that would need just ten per cent of the fuel of a conventional landing.

The trouble was, nobody had ever tested the idea, even on Earth, let alone the Moon. And Soyuz wasn’t built for it anyhow; there was a consensus that you’d need significant advances in a number of material technologies to make the technique reliable, if it was possible at all.

And besides, all pilots who looked at the papers hated the whole idea. If it was ever applied at all, surely it would be only for unmanned cargo drones.

But — as Arkady had immediately realized when he heard Henry’s request — in the current circumstance, there was really no choice at all.

He would go through with this because he had faith in Henry, and because he trusted Geena; her relationship with Henry had finished unhappily, but she would not select a fool.

And besides, as far as he could see, it was only Henry who had fully understood the implications of the Moonseed infestation from the beginning, and so Arkady must do what was necessary to implement his plans.

But on Earth, arguments raged on.

There were hardly any scientists who were prepared to validate Henry’s grand proposal. The Americans” greatest concern seemed to be allowing a Russian access to their prized weaponry.

The Russian authorities were rather more focused on the humanity of it. TsUP at Korolyov at first flatly refused Arkady permission to proceed with this scheme. Breaking with custom, his personal physician was brought on the loop to try to persuade him to return to Earth. If he came home, perhaps some alternative plan could be found — for instance, perhaps an unmanned missile could deliver a nuclear weapon as Henry desired.

But Arkady knew that could only cause delay. And it was self-evident that launches of any kind might soon become impossible from the surface of Earth; already many facilities at Canaveral had been destroyed in terrorist actions, and were in any event under threat from tsunamis. This might be the only chance.

In an attempt to persuade Arkady to desist, they even flew in his sister to TsUP, and had her talk to him on the ground-to-air loop.

It was never easy, Arkady had found, to talk to family and friends from space. Life in space — even on a routine Earth-orbit mission — was rather like a commercial airline pilot’s: hours of tedium, punctuated by moments of extreme terror. If you tried to describe the tedium, it was simply dull; if you talked about the terror, you sounded melodramatic — worse, you might finish up frightening the person who cared about you enough to call you.

It made for awkward conversation.

But his sister knew him, and was wise. Nor would she play the part demanded of her by TsUP.

She spoke to him of simple family matters. Vitalik asked me to say hello, she said. Vitalik was Lusia’s son, Arkady’s nephew. He is at summer camp. He is getting happier. He swims in the sea, he rehearses plays, he is doing arts and crafts. It was different in our day.

“Yes.” At the Soviet pioneer camps when Arkady was a boy, the children had been subject to meetings and political training, so much so they were sometimes deprived of sleep. Not everything about the breakup of the Soviet Union, they agreed, was necessarily so bad. And so on. Lusia spoke further of Vitalik’s small projects and achievements.

She said nothing of his intentions, the fate of the world. She was simply saying goodbye, on behalf of the world, the family he had left behind.

She knew, as he did, that his proposed course of action would mean the final sacrifice. Even if, by some miracle, he survived the landing itself, he could not hope to live through what followed.

But then Henry and Geena were making as big a sacrifice.

There was really no choice.

It was a duty; it must be done.