He clambered out quickly, and stood on the Arduan ground once more. He watched Kalinski follow cautiously, slowly given the burden of the higher gravity, but her face was full of wonder, or astonishment. Her first moments on an alien world.

Standing together, they turned around. Much had indeed changed. The thick Hub forest still stood, but dead leaves hung limply from the stubby upper stem branches, the undergrowth had died back, and there was a huddle of dead builders, not a purposefully constructed midden but just a heap of corpses, on which, Yuri saw, frost had gathered. Frost, at the substellar. His breath fogged.

‘Hello, Yuri Eden.’

Yuri turned. There was the ColU, its dome smeared with some kind of ash, its upper surfaces rimed with frost. Yuri felt oddly touched. ‘You waited for me.’

‘Yes.’

‘For eight years? Jesus. Looks like you stayed in the very same spot.’

‘No. That would have been foolish. I moved periodically in order to ensure the smooth functioning of my drive mechanisms and—’

‘All right, I get it. This is Stef Kalinski. Colonel in the ISF.’

‘I know of you. Welcome, Colonel Kalinski.’

Kalinski just stared.

‘Yuri Eden, you left Mercury four years ago. We received warning of your coming a short time ago, you and your companion.’

‘Ah,’ said Kalinski. ‘The message beat us, just as when you came through the other way, Yuri. The transit’s not quite lightspeed.’

‘The message was received by Captain Jacob Keller in the hull, who informed me.’

Yuri asked, ‘Keller? What about Brady?’

‘He has not survived. We keep each other company, Captain Jacob Keller and I. Sometimes we play poker.’

Yuri had to laugh. ‘Poker. My God. ColU, the weather – what happened here?’

‘Volcanism, Yuri Eden. It seems that a major volcanic episode has occurred, probably in the northern region, from which we fled with the jilla and the builders.’

‘Ah. All that uplifting.’

‘Yes. It is not an uncommon occurrence on this world, it seems. That is, not uncommon on a geological timescale.’

‘And now,’ Kalinski said, ‘we’re in some kind of volcanic winter.’

‘No doubt for the native life forms it is part of the natural cycle. A spur to evolution perhaps. But the humans here have suffered. Of course the star winter was already a challenge. All this has happened in the interval while you fled, dreamless, between the stars.’

‘My God. If it’s as bad as this here, at the substellar . . . Where are they, Delga and the rest?’

‘Gone from here, Yuri Eden.’

Yuri glanced around, at this utterly transformed wreck of a world, to which he had now been exiled by the mother of his child, as once he had been exiled to the future by his parents. He felt his heart harden, as he stood there in the unexpected cold. ‘OK. Well, there are big changes on the way, ColU. Floods of immigrants are going to be coming through that Hatch. I don’t imagine the UN will wait the eight years it will take for our bad news about the volcanic winter to reach them, for that process to start.’

‘Or even,’ Kalinski said, ‘for confirmation that the Hatch is actually two-way, that it’s safe to pass through. I know Michael King.’

‘We must help them,’ the ColU said.

‘Yeah. But we’ll be in charge,’ Yuri said firmly. Kalinski looked at him strangely, but he ignored her. ‘ColU, let’s go to the hull, and get some warm clothing, and work out where to start.’

‘One thing, Yuri Eden.’

‘Yes?’

‘I heard about the decisions made on Mercury. I’m sorry for your loss.’ It held out a bundle of dried-out stems. Mister Sticks.

Yuri took the doll.

Then the ColU whirred, turned, and rolled away along a track that was now well worn, trampled down by eight years of use. Yuri followed briskly, carefully carrying the beat-up little doll.

SIX

CHAPTER 65

2202

Five years after Stef Kalinski had disappeared into the Hatch to Proxima – and because of the lightspeed delays, with three more years left before Penny could even in principle discover for sure if her sister was alive or dead – Penny was invited to another major UN-China conference, this time on the cooperative exploitation of solar-system resources, to be held on Ceres, the Chinese-held asteroid.

Once again this was going to be all about politics and economics, not physics, and her first instinct was to refuse. But she came under heavy pressure to attend. As Sir Michael King and others pressed on her – she even got a note from Earthshine – for someone like her, so closely associated with kernel physics, to be invited to a conference on Ceres itself on UN-Chinese cooperative projects was a hugely symbolic gesture, just as before. But, aged fifty-eight now, she was a card that had been played too often, she thought. She was like an ageing rock star pulled out of retirement to celebrate the birthday of one too many Secretary Generals. A statement of mutual trust that, in the light of the ever worsening political situation, every time it was repeated had an air of increasing desperation about it.

And meanwhile there was increasingly bad news from all the worlds of mankind. Recently there had been heavily publicised (and suspiciously scrutinised) ‘disasters’ on both political sides: a tsunami in the Atlantic, a dome collapse in a Chinese colony in the Terra Sirenum on Mars soon after . . . At first it looked as if each of these was natural, a gruesome coincidence of timing. Then fingers started to be pointed, accusations began to be made. Fringe groups claimed responsibility for the ‘attacks’, one in retaliation for the other. Some groups claimed responsibility for both.

But neither might have been attacks at all. Penny couldn’t see how you could determine the truth. Perhaps, given the poison of international relationships, the truth, in fact, didn’t matter any more. She was hearing dark conspiracy-theory mutterings of drastic provisions being drawn up by both sides in this gradually gathering war: fleets of kernel-drive battleships being constructed by the UN side, various exotic uses of their own interplanetary technology being planned by the Chinese . . . She supposed with her contacts she was in a better position than most to ferret out the truth of such rumours. But she preferred not to listen, not to think about it.

And now here she was, summoned to an asteroid. Still, King said with a wink, it might be fun to see Ceres.

The trip itself, her latest jaunt out of the heart of the solar system, began reasonably pleasantly. Aboard an ISF hulk ship running at a third standard gravity, close enough to Mercury-normal for her to feel comfortable, she had her own room, a workstation, and a generous allocation of communication time with Earth and Mercury, even though the round-trip time delays soon mounted up. She got a lot of work done, on a securely encrypted standalone slate. Kernel physics was still a closely guarded secret as far as the UN was concerned, although Penny did often wonder how much the Chinese must have learned through their various intelligence sources by now.

She had to make the trip in stages. Just as hulks were not allowed within the environs of Earth, so no UN-run, ISF-crewed kernel-powered hulk was allowed within a million kilometres of Ceres, the Chinese central base in the asteroid belt. The ISF crews joked blackly about what the Chinese could actually do about it if a hulk crew refused to comply and broke through the cordon, especially if it came in on the delicate Halls of Ceres in reverse, with the cosmic fire of kernels blazing from its rear like a huge flamethrower. But those arrogant kernel-tweakers of the ISF, Penny reminded herself, depended for all their achievements on a wholly inhuman technology: a technology that, some believed, humanity shouldn’t be using at all.