Dr Kalinski had done his best to shield his project from those criticisms. Yes, he had needed some big-scale equipment, but even though he had reused a solar-power station, itself a much-hated relic of the past Heroic age with its hubristic planetary engineering schemes, he would use energies of orders of magnitude less than those that had hurled Dexter Cole to Proxima. As for profit, Dr Kalinski eschewed any cash rewards save for the salary he drew from the academic institutions that employed him. Any patentable technologies would be owned and exploited by those institutions, on behalf of the UN-governed taxpayers that supported them. And, yes, Angelia was an advanced, sentient AI, the mission could not have been achieved without smart onboard technology. She was capable of suffering – that was the price of sentience. But the mission was designed to sustain her, Dr Kalinski said, to deliver her to Proxima Centauri alive and sane. She was being honoured, not mistreated.

But the team were evasive when they discussed details, and Dr Kalinski would not look Angelia in the eye – or eleven-year-old Stef, Angelia noticed. Evidently there were things she, and Stef, hadn’t been told about certain aspects of the mission.

Despite such tensions it was a wonderful, warm, immersive final evening for Angelia. And at the end, as the dinner party was breaking up, Stef Kalinski came to her and took her hand.

‘I’m sorry if I’ve been nasty to you,’ Stef said.

‘You haven’t been.’

‘It’s just a bit difficult for me. My mother died, she was French—’

‘I know.’

‘And then I had Dad all to myself in Seattle. Then you showed up. It’s like . . .’

‘Yes?’

‘Like I suddenly had a big sister.’ She screwed up her small face, thinking hard. ‘Like I had to get all my sibling rivalry out in one go.’

Angelia laughed. ‘You’re very perceptive. And very self-aware. I haven’t been offended. I’m glad I had the chance to get to know you.’

‘Yes. Me too.’

‘Are you jealous of where I’m going, the adventure I’m going to have?’ It was a reaction she’d encountered from several of the ground crew – Bob Develin, for instance, a thirty-year-old from Florida who’d spent much of his youth working on the underwater archaeology of a drowned Cape Canaveral, and dreaming of space.

But Stef shook her head. ‘Oh, no. The kernels – that’s what I want to study, even if Dad thinks it’s cheating to use them, or something.’

‘You don’t want to go to the stars?’

‘What for? Stars are easy to understand . . .’

Maybe so. But as Stef got up on tiptoe to kiss her synthetic sister on her programmable-matter cheek, Angelia wondered if even a kernel could be as complex as an eleven-year-old girl.

That was the end of the night. Dr Kalinski showed Angelia to her room, an authentic human space with a regular bed and a wall mirror and everything. He stroked her artificial hair and said goodnight. She laid down on the bed, fully clothed, and entered sleep mode.

When she woke, she was in space, pinned by sunlight.

CHAPTER 11

She no longer had a human form, not remotely. Now she was a disc spun out of carbon sheets, a hundred metres across and just a hundredth of a millimetre thick. Yet she was fully aware, her consciousness sustained by currents and charge stores in the multilayered mesh of electrically conductive carbon of which she was composed. She had slept through this transformation, this atomic-level reassembly conducted by Dr Kalinski and his technicians.

And she could see, hear, taste the universe, through clusters of microscopic sensors.

She faced Mercury, a cracked, pitted hemisphere. The lights of humanity glimmered in the shadows of ancient crater walls, and crawled along cliffs and ridges. Orbiting the planet she saw the hard, ugly lump of the defunct solar-power station, assembled decades ago in near-Earth space and now hauled here for reuse, and the tremendous lens, a structure of films and threads that dwarfed even her own lacy span, that would throw the station’s microwave beam across the solar system to power her flight. The scale of all this was extraordinary, and the energies to be unleashed were huge. If anything went wrong she would die in a moment, a moth in a blowtorch. She felt a stab of unreasonable fear.

‘Angelia?’

‘I’m here, Dr Kalinski.’

‘How do I sound?’

‘Like you’re in a room with me.’

‘Good. That’s how I wanted it to be. I’m glad we had time to be human together. Because you are part of humanity, you know. The best and brightest part. You are named for a daughter of Hermes, the Greek version of Mercury. She too was a messenger, a bringer of tidings. You will carry the news of our existence to another star. And you will carry all our dreams. Mine, anyway. Well, we said all that. You know we can’t communicate while the beam is firing. We’ll talk to you in four days, when the acceleration is done. All right?’

‘Yes, sir. I think—’

‘We won’t put you through a countdown. Godspeed, Angelia . . .’

The power station lit up in her vision, which was sensitised to the beam’s microwave frequencies. Mercury receded, as if falling down a well.

The intense radiation, intended originally to deliver compact solar power to the factories and homes of distant Earth, now filled her own hundred-metre-sail body. She felt her skin stretch and billow as terawatts of power poured over her. It was not even necessary for her structure to be solid; her surface was a sparse mesh, a measure to reduce her overall density, but the wavelengths of the microwave photons were so long that they could not pass through this wide, curving net of carbon struts. And the microwave photons, bouncing off the sail like so many minute sand grains, shoved her backwards, at thirty-six gravities, piling up an extra thousand kilometres per hour of velocity with each new second.

Despite the increasing distance, the intensity of that laser beam, focused by the lens, did not diminish, not by a watt. It was agony. It was delicious. She laughed, deep in her distributed consciousness.

The intensity did not diminish for four days, by which time she had been flung more than a hundred times Earth’s distance from the sun, far beyond the orbit of the furthest planet.

From here, the sun, the monster that dominated Mercury’s sky, was no more than a bright star – and a star that was very subtly reddened in her sophisticated sensors, for she had already reached her interstellar cruising speed, of two-fifths of the speed of light. At such a speed she would reach Proxima in a mere decade. Orders of magnitude less energy had been expended to get her this far, this fast, than had been spent on Dexter Cole. But he, cryo-frozen, had been embedded in a thousand-tonne craft; she was a mere eighty kilograms – the mass of a human, as if Cole, naked, had been thrust to the edge of interstellar space.

She was the craft herself. And she, indeed, was a throng; she would never be alone.

With an effort of will, a subtle reprogramming of her structure, she turned her senses outward, to the void.

CHAPTER 12

2169

The shuttle was to stay on the ground for ten days, before returning to the Ad Astra.

The main task for the crew in this interval was unloading, assembling and installing the colonists’ supplies and gear. The colonists, meanwhile, were put to work constructing irrigation ditches to a nearby lake, and making a start on a shelter, dug into the ground.

The shelter was for protection from stellar storms. Proxima flared. It happened once or twice a day. You could see it with the naked eye; whole provinces would light up on the star’s big dim surface, like a nuclear war going on up there. The planet, Prox c, had a thick atmosphere and a healthy ozone layer, but about once a month, it was thought, there would be a storm severe enough to require more protection. For now, if a bad flare came they would be allowed back in the shuttle. But in future they would be scurrying into holes in the ground.