‘Tough break.’

‘You could say that. We talked about this before. I’m too old now; I have a leathery hide.’

Earthshine, sipping his own virtual coffee, said gravely, ‘I believe I can sympathise. I remember being human, but I am no longer human. My consciousness can easily be modified, reworked, replayed, edited . . . As perhaps yours has, or your sister’s. It is your unique misfortune, Penelope Kalinski, yours and your sister’s, that your personal timeline has somehow been tangled up in the mysteries of kernel physics.’

Penny thought that over. ‘Thanks. I think.’

King winked at her again. ‘You’re here, in this room, with me. You’re real enough. Forget the existential crap. You’ll be fine—’

And now there was movement on the screen, and they turned to watch. The Deputy Secretary General, slim, smart, very sombre, stepped up, holding a slate. She began to speak, and English, Spanish, Russian and Chinese subtitles peppered the screen. But a headline strap at the bottom, scrolling by, was all Penny needed to know what had happened.

Earth was to be protected. That was the only agreed conclusion of talks which had once again broken down. Otherwise all bets were off. There was no declaration of hostilities, not yet, but—

Earthshine stood up. He flickered, oddly, as if massive processing resources were being diverted. ‘The talks are finished. There will be war. It is obvious, a Cold War logic, like the twentieth century. Each side now has an interest in striking first, before the other destroys its capability. Take me off Earth.’

Penny glanced at King, who was staring at the screen, ashen-faced; evidently this news was worse than he’d expected. He quickly pulled himself together, and looked up at Earthshine. ‘Very well. I have a ship. You can use it. But let my family stay here.’

Penny was astounded by the suddenness of these negotiations. ‘Off Earth? But . . .’ But if anybody understood the implications of what was happening, this shadow play of delayed press conferences and ambiguous statements, it was these two. She thought it over, then stood up. ‘I’ll help you, Earthshine. I can continue to advise you. Take me with you, on the ship.’

Earthshine nodded. ‘Done.’

‘And Jiang Youwei,’ she added hurriedly.

‘Agreed.’

CHAPTER 80

It had taken the expedition two weeks to skirt the island continent.

Then they cut away from the coast, and headed once more over the ice-covered ocean, the vehicles rolling smoothly side by side. In this flat emptiness, again Yuri’s sense of time seemed to dissolve. He dozed, watched the stars, and played chess with Liu. Whole days went by without him even leaving the rover cabin.

It was almost a surprise when the ColU called a warning that another landfall was imminent. After nearly a hundred days, more or less on schedule, they approached the rising ground of the frozen rock-tide bulge that supported the antistellar point.

They proceeded with caution, as ever. But this time they wouldn’t stick to the coast; they were heading for the heart of this peculiar star-born continent. Soon the vehicles were clambering up onto the rising flanks of an ice sheet, with the summits of worn mountains protruding, shadows in the starlight. The ColU led the way, nosing through passes, pushing ahead on stretches of open country. The ColU said it was navigating using the stars, as well as its own internal dead-reckoning gyroscopic systems, feeling its way towards the precise antistellar point, the summit of this ice cap.

Stef, meanwhile, became increasingly fascinated by the anomalous star-that-wasn’t-a-star that hung high in the sky above. Eventually, almost as they arrived at the substellar point, it occurred to her to examine its light with a spectroscope.

She immediately called a halt.

They pulled on their cold-weather gear, clambered out onto the ice, and stood together, peering up at the star, almost directly overhead. Stef held up a mittened hand, holding a small radio transmitter.

Yuri stood with her. ‘Tell me, then. What about your star?’

‘It’s not a star at all. I think I know what it is. All this way I watched it rise, like a naked-eye astronomer five hundred years ago. I was puzzled. It just didn’t fit . . . Finally I checked it out spectroscopically.’ She pointed upwards. ‘That’s Proxima light.’

Yuri did a double-take. He looked up. ‘It can’t be. Oh. Yes, it can – reflected, right? Then it’s a mirror.’

‘Or a solar sail. Something like that. Yes.’

‘But it’s just hanging there. How come it’s not in orbit?’

‘I think it’s at an equilibrium point. The pressure of Proxima’s light, pushing it away, is balanced by the pull of gravity, drawing it in. I’m not sure it’s stable, but with some conscious management—’

‘Conscious? You know what this is?’

‘I think so. Excuse me.’ She raised her radio. ‘Come in, Angelia. I think I have the right frequency . . .’

‘I am Angelia 310999,’ came a faint reply, a female voice, a kind of clipped accent very like Stef’s own. ‘Hello, Stephanie. It is good to see you again. I remember our time on Mercury very well.’

Yuri and Lu just stared, at Stef, at the bauble hanging in the sky.

‘We’ve both come a long way from Mercury. Although nobody calls me Stephanie any more. In fact, they didn’t back when I last spoke to you, I’m Stef to my friends . . . Can you see us?’

‘Oh, yes. Your vehicles are quite clearly visible; my optical systems continue to function well. Although I could not identify you, of course, until you spoke to me. How is your father?’

‘Passed away, I’m afraid, Angelia. Long ago.’

‘Ah. He was a visionary, though morally flawed.’

‘Yes. Angelia, I can see that you succeeded in your mission.’

‘It was very difficult. Much was lost.’

‘Why didn’t you report to Earth? Why not contact the Ad Astra, when it arrived?’

‘It did not contact me.’

‘I doubt they even noticed some defunct lightsail space probe,’ Liu murmured.

‘Less of the “defunct”,’ Angelia snapped.

Liu, surprised, laughed.

‘Stef, humanity did nothing for me. I, and my equally sentient sisters, were thrown into the fire in the hope that a handful of us would succeed in a mission ordained by others.’

‘Hm,’ Yuri said. ‘Sounds familiar.’

‘Why should I obey the orders of those who intentionally harmed me and my sisters?’

Liu rolled his eyes at Yuri. ‘Another bit of too-smart AI. Why do these things never do what they are supposed to?’ Shaking his head he walked away, tentatively exploring, pushing deeper into the dark, his flashlight casting a glow on the ice at his feet.

Stef said, ‘All right, Angelia. I guess I understand. My father had his problems, but he was still my father. Our father, I guess. And you were one sibling I never resented.’

‘Stef? I don’t understand that last remark. I remember how you and your sister, Penelope—’

‘Never mind. Long story. We’ll talk about it some other time. Angelia, what are you doing up there?’

‘It is a good place for me to stay. Me and my surviving sisters. Obviously it is a point of stability. And we serve a purpose.’

‘A purpose?’

‘Lighting the way to the point very close to where you stand. The antistellar. The most significant point on the planet.’

Yuri looked up again. ‘It is?’

Stef said, ‘So we didn’t really need to navigate, did we? All we had to do was look for you. Follow the star. Just like Bethlehem.’

‘And of course I sought out the one who came before me . . .’

‘Who do you mean?’

Liu came running back, breathing hard. ‘You need to come. I found something. Get the rover.’

CHAPTER 81