Lex shook his head. ‘No offence, Angelia, but nothing you will ever do could match the achievement of Dexter Cole, no matter how his mission pans out.’

Stef knew Cole’s story; every kid grew up hearing about it. When a habitable planet of Proxima Centauri was discovered, nations in what had since become the western UN federation had banded together, and within a couple of decades had scraped together a crewed mission. Cole had launched from Mercury for access to its energy-rich solar flux, just like Angelia would. A tremendous laser beam, powered by that flux, had blasted into a lightsail, sending Cole’s thousand-tonne ship to Proxima. Dexter Cole was flying alone to the stars on a forty-year, one-way mission – and, in some sense Stef had not been allowed to discover, he would somehow become the ‘godfather’ of a human colony when he got there. All this had been launched from an Earth still reeling from the aftermath of the climate Jolts and the Kashmir War of the previous decades, an Earth where the huge recovery projects of the Heroic Generation were still working through their lifecycles – all this as mankind was only just making its first footfalls on the worlds of its own solar system. Incredibly, having been launched decades before Stef was born, Cole was still en route; right now he was in cryo, dreaming his way between the stars, before a pulse-fusion rocket would slow him at the target.

Lex said, ‘Cole is a hero, and I intend to follow in his footsteps, some day.’

Angelia smiled again. ‘Hey, it’s a big universe. There’s room in it for both of us, I figure.’

Lex grinned. ‘Fair enough. Good luck, Angelia.’ He stuck out a hand.

She approached him and took his hand. And as Stef watched the bit of stone Angelia had swallowed popped out of the back of her neck, and dropped slowly to the ground.

CHAPTER 6

On the day the I-One was to be launched, Stef stood with her father at the window of the UN-UEI command bunker.

This stout building, constructed of blocks of Mercurian basalt, was set high in the walls of Yeats’s rim mountains, and looked down on the crater-floor plain. The big room was filled with the mutter of voices and the glow of monitor screens, teams of engineers tracking the countdown as it proceeded. Through the bunker windows, in the low light of the sun, Stef could see the domes, lights and tracks of the main Yeats settlement, and in the foreground the complex activity around the International-One at its launch stand, bathed in floodlights. The slim prow of the ship itself just caught the sun as it rose, agonisingly slowly, above the rim mountains. The ship was so far away it looked like a toy, a model layout; the VIPs in here were using binoculars to see better, ostentatiously demonstrating that they lacked Heroic Generation-type ocular augmentation, now deeply unfashionable.

Supposedly, the launch pad was far enough away for them to be safe here in this bunker if the worst came to the worst. But Stef had learned by now that although the engineers had figured out how to manipulate the kernels, which were evidently some kind of caches of high-density energy, nobody understood them. And if something went wrong, nobody knew what the consequences might be. This robust bunker might turn out to be no more protection than the paper walls of a traditional Japanese house before the fury of the Hiroshima bomb.

And somewhere in the middle of all the potentially lethal activity down there was Lex McGregor, just seventeen years old. Stef saw his face on a monitor screen. He lay on his back like his older companions, calm, apparently relaxed, contributing to the final countdown checks.

‘He looks like John Glenn on the pad,’ her father said, looking over her shoulder. ‘Heroic images from the best part of two hundred years ago. Some things don’t change. My word, he’s brave.’

Maybe, Stef thought. She did admire Lex, but there was something slightly odd about him. Off-key. Sometimes she suspected he’d had some kind of augmentation himself, so his reactions weren’t quite the human norm. Or maybe it was just that he was too young to be scared, even if he was six years older than she was.

Her father said now, ‘This landscape has been sleeping for billions of years, since the last of the great planet-shaping impacts. If that damn ship works this crater is going to be witness to fires fiercer than any that created it. And if it fails—’

‘It should not fail,’ Angelia said. The strange ship-woman stood on her father’s other side – one ship watching the launch of another, Stef reflected. ‘The testing has been thorough.’

Stef’s father grunted, sounding moody. He was in his fifties, a thickset, greying man, with old-fashioned spectacles and a ragged moustache; he had always been an old father to Stef, though her French mother had been much younger. Now the low light cast by the display screens in the bunker deepened the lines of his face. He said, ‘Somewhere up there, you know, is my SPS. An old solar-power station hauled out from Earth, a brute of an engine left over from the Heroic days and now refitted and put to good use . . . Oh, they sent Dexter Cole to the stars, but what a cockamamie way to do it, a lightsail to get him out of one system and a fusion rocket to slow him down in the next. Like those old Greek ships, rowing boats with sails attached. Still, they did it, they got him away. Now you, Angelia, you represent the next generation, the next phase of human ingenuity.

‘And, just at this exquisite moment – this. The discovery of the kernels. A source of tremendous power that, it seems, we can just turn on like a tap. Everything we mere humans can manage is suddenly put in the shade. It’s as if we’re somehow being allowed to cheat. Does that seem right?’

Stef was puzzled. ‘You’ve talked about this before. I’m not sure who you’re blaming, Dad.’

‘Your father has always been an agnostic,’ Angelia said. ‘Not God.’

‘Not God, no. I just keep thinking it’s a damn odd coincidence that we find these things just when we need them . . .’

The murmuring voices around them seemed to synchronise, and Stef realised that, suddenly, the countdown was nearly done, the I-One almost ready to go. She glanced once more at Lex McGregor, on his back, apparently utterly calm.

Flaring light flooded the bunker.

Stef looked through the window. The light was coming from the base of the ship, a glare like a droplet of Mercury sunlight. As she watched, that point of light lifted slowly from the ground.

The bunker erupted in whoops and cheering.

‘Watch it go, Stef,’ said her father, and he took her hand in his. ‘It’s on a trial run out to Jupiter, at a constant one-G acceleration all the way. If it works that damn drive should be visible all the way out, like a fading star. This is history in the making, love. Who knows? It might unite us as humans, at long last. Or it might trigger some terrible conflict with the Chinese, who are denied this marvellous technology. But it’s certainly a bonfire of my own ambition.’

Angelia put a comforting arm around his shoulders.

Stef barely paid any attention. Staring into that ascending fire, she had only one question. The kernels. How do they work?

CHAPTER 7

2169

Day one thousand, two hundred and ninety-seven.

That was Yuri’s count, by the tally he had kept running in his head, recording the eight-hour shift changes since he’d woken up in the hull. Over three and a half years. There were no calendars on the Ad Astra, not that the passengers saw. And of course he had slept through the early weeks of the flight from Mars, an uncountable time. But he knew roughly that the journey was due to end about now. Day one thousand, two hundred and ninety-seven.