Zhi grinned. ‘If you need to throw up, Commodore Regent, use your hat.’

  ‘Just Captain, asshole. Shit. Goes to show how your body remembers stuff. Once I knew this place like the back of my own eyelids. But now it feels like a fairground ride. They sure made a mess of our station, didn’t they?’

  ‘Unfortunately, yes. The times we live in, Harry.’

  Harry glanced up at him. ‘And people have lost a lot more. I know, my friend.’

  They reached the outer rim and made their way along what was effectively a stretch of curved corridor, made up of Shelter units, boxy modules each twelve metres long, four wide, joined end to end by flexible airtight junctions. Once, a stately rotation had delivered a steady gravity of about Earth normal here. But now the rotation was gone, the stars in the pitch-black sky, visible through the many windows, stationary.

  ‘I remember Ange Costello running down here,’ Harry said now. ‘Around and around, with the rest of us cowering out of her way.’

  ‘Well, the perimeter was nearly four kilometres. Even I ran a lockdown marathon once . . . You couldn’t do it now. It’s not a complete circuit any more, since the cannibalisation. Here. Good view of the construction shack.’

  They paused and peered out of the windows, drifting from location to location. The installations beyond were brilliantly lit.

  Harry screened his eyes, wincing. ‘Wow. So bright.’

  ‘I know. Once this was one of the darkest places in the Solar System, remember? The deep shadow of the Earth. The reason we came, the reason we built our big telescopes here. Well, now it’s a construction yard. Where we are building that.’

  And he pointed to a boxy hulk, adrift in the glare of the spots.

  Most of it was a ‘jig factory’, jargon for a kind of frame of trusses, beams and girders set out in the rough shape of the final craft, and into which various components could be manoeuvred with precision, mated, fitted out. Zhi made out the glare of welding torches, wielded by a phalanx of drones that cautiously worked their way along the assembly. The drones ran on rails or cables stretched out along the trusses, smoothly, precisely, with high energy efficiency.

  This was the way you built things in space, Zhi knew. Most days no humans went out there at all. It took too long just getting ready for an EVA and decompressing later, and humans were a lot more prone to making mistakes.

  ‘So,’ he said hesitantly. ‘Behold Pioneer 14.’

  ‘Those are more standard Shelter modules, aren’t they?’

  ‘You got it. And you can see how that main hull has been put together. It’s never going to be pretty. We used forty modules in all.’ Drifting in the air, he mimed a square shape with his hands. ‘You make a frame of four modules, twelve metres long, four metres thick. And you stack ten such frames, weld them together, to give you a hollow box forty metres long. When inessentials and double walls have been stripped out, the mass will be about that of the old ISS – including the ramscoop, which masses next to nothing. What do you think?’

  ‘I think,’ said Harry, the crisp blue of his jacket reflecting in the windows, ‘that will be one impressive mother. But ugly as sin. And all of it cannibalised from the Lodestone?’

  ‘Afraid so. Well, the scoop itself is a specialised build, of course. Much of that boxy hull will be living space – we’re looking at a mission of a few years. And, you won’t like this, we had to cannibalise some of our astronomy instruments to build the sail’s central frame, and other vacuum-friendly infrastructure. That broke our hearts, I think.’

  Regent winced. ‘I bet. But don’t blame yourself. It’s not an age when science, pure science anyhow, is a priority. Not any more. Which is why I’m back wearing the blue. That dark energy ramscoop, though. I hesitate to ask. I don’t suppose you’ve got around to proving that the technology actually works.’

  Zhi grinned. ‘You always were a shitter. We did fly the Sputnik, you know. That was a decent technology demonstrator. And as for proving we can scale it up – well, that’s what the Pathfinder is for.’

  ‘The Pathfinder? Oh, your Gemini . . .’

  Zhi pointed to a smaller structure off in one corner of the visual field, overwhelmed by the hull of the greater craft. Just a single square frame.

  ‘Four modules only, stripped down to about forty tonnes. Big enough to take a couple of crew, however. We’ll install a scaled-down dark energy scoop, and load up crew – and, well, fly it up and down the umbra, the shadow of the Earth, as with the Sputnik. No sunlight pressure, to prove the dark energy drive.

  ‘And then we plan to make more extensive journeys. You know how it is with a new ship, let alone new technologies. The more you can learn about its handling characteristics the better. Possibly a jaunt out to the orbit of Mars, following a Hohmann orbit, more or less. Yes, Serena does think of it as our Gemini programme, which was a proving step before Apollo. Ito Katsuo and Ange Costello are down as prime crew for the Pathfinder, by the way. Ange is still station commander and deserves some time off the base.’

  ‘Ito’s the Mars astronaut. On your prime crew for Pioneer also?’

  ‘Right. So we figure at least one of us should have direct experience of handling the dark energy ram.’

  ‘OK. And then it’s off to the Kuiper Belt?’ He clapped Zhi on the back, making Zhi grab a handhold for support. ‘Well, I’m impressed, old buddy. Not convinced, but impressed.’

  Zhi snorted. ‘You’d give your right leg to get that gig.’

  ‘If you say so.’ He glanced at his phone. ‘But I do know that Jones will chew off both our right legs if we are late for her briefing. Come on.’

  They moved off, Zhi leading.

  Harry called ahead, ‘And don’t think you can lose me by running ahead, asshole. You made a mess of my beautiful station, but I still know it like the inside of my eyelids – ow! Shit, who put that brace there? . . .’

  Zhi knew that the space Serena Jones called her ‘ready room’ was not much more than a standard crew cabin with a few minimal extras, even though it was receiving such an illustrious visitor as the President’s science adviser. The cramped compartment with the standard fittings, the fold-down bed and fold-up table, the lockers for spare clothing, personal gear and work documentation crammed into the spaces behind the wall panels. A door to a small private shower room was half open. But Serena had one main privilege, a minuscule private kitchen area with a water spigot, where she kept a coffee printer, with flasks floating in the air, attached by cords to hooks on the wall.

  Aside from that it was a work space, a nest of papers and manuals, and screens stuck to every surface, most of them scrolling with text or refreshed imagery even now.

  Zhi always thought this was stimulating, somehow. Proof of Serena’s own hands-on approach to stuff. And Yamanaka, once she was floating free amid the debris with a coffee flask in her hands, looked interested, even pleased.

  Sara West, meanwhile, the growly, faithful engineer, evidently out of her depth, was just as evidently trying to keep out of the way. Embarrassed even, Zhi thought, unsure of her place here. That was what politics did to you.

  Harry, meanwhile, on entering the room, looked professionally suspicious. He held up his palm, waved it back and forth, and checked a monitor on his uniform sleeve. ‘Excuse me,’ he said, not looking up. ‘Should really have let me in here before Prof Yamanaka. Protocol.’

  ‘Just doing your job, I know,’ Jones said. ‘Sorry for being so messy, today of all days. I should have thought you’d need to check it out.’

  ‘As you say. Just my job.’

  Yamanaka beamed. ‘Well, I can tell you I feel right at home in here. I’m a working scientist, remember – when I get the chance. And, believe me, my offices back home are every bit as messy and chaotic and as gloriously creative as this. I never throw everything out either. Why, I noticed this.’ She pawed through a cloud of roughly gathered debris in a net in one corner, and retrieved a crude model, a rough wheel shape. ‘Drinking straws? Cut down to some standard length and glued end to end . . .’

  Serena smiled. ‘Well, here you are in the real thing. This was our first conception of the Lodestone, at the Jones, Inc. skunk works in California. I grew up with CGI and virtual modelling, but I was a kid who always liked to make stuff I could touch and hold.’

  Zhi grinned at Sara, and they both parroted, ‘Water rockets in the back yard!’

  ‘OK, OK. You two have heard too many of my pitches. The principle still stands, though. This is large-scale engineering. But you need to fill your imagination with what the finished product will look like before you can even begin—’

  ‘And in that case,’ Yamanaka cut in, waving a hand, ‘I hope you have plenty of spare drinking straws around. Because I’ve come to ask you to change course. Or at least to tack a little in the breeze . . .’ None too discreetly she glanced at a time display on one wall. ‘We’d better get on with it. I am due to brief the White House in less than an hour.’

  Zhi, feeling protective about the project, frowned. ‘Brief them about what? What change of course? You know what we’re doing here. The whole world does. Because we told them, back in the day. This is America’s highest-profile direct response to the Galaxias intervention. And Serena made sure the goal was clear. Three people, destination Centaurus, there in a decade. So I don’t see what other priority—’

  Jones held up her hand, silencing him. ‘Let’s hear what Professor Yamanaka has to say.’

  Yamanaka nodded, somewhat sombrely. ‘Thank you. Yes, you’re right, Zhi, this is already a very high-profile project. The public supports its goals, and supports the President for backing you – the polls are holding up, anyhow. But things have changed.’

  Zhi snorted. ‘You mean, President Cox is facing a challenge from that loudmouth Stringer?’

  Harry touched his arm, gently. Shut up.

  ‘Actually, yes, you’re right,’ Yamanaka said. ‘The President is facing a tough re-election campaign; everybody knows that. Probably any sitting President would in the present circumstances. And, yes, Stringer is questioning the value of Pioneer; yes, the President is having to defend you. But that’s not the primary problem.’

  ‘Then what is?’ Zhi asked.

  She looked at him sadly. ‘The Chinese, Zhi. Your own mother – possibly. That’s who.’

  Zhi frowned. ‘I’ve heard nothing from my mother save for routine stuff – family stuff – for months now.’ He tried not to blush. ‘Last time I got a call from her, I was allowed to take it up here, it was because I forgot her birthday.’

  A gentle punch on the arm from Harry Regent. ‘Asshole. Family 101.’

  Yamanaka considered Zhi, not unkindly. ‘I don’t blame you for being out of touch. Even if not for the security restrictions on communications, you’ve been very busy up here, obviously. The trouble is, Zhi, we suspect your mother has been busy too. I bet any radio silence from her started around fifteen months ago.’

  ‘Why then? . . . Oh. Mercury.’

  ‘Right. Because that’s when the Chinese, very publicly, launched the first of a small fleet of automated craft, from the Moon, to Mercury. That’s why. But we still have no real idea what they are doing there.’

  Jones nodded. ‘I’ve seen some of the background briefing myself. The trouble is—’

  ‘What?’

  ‘There isn’t much of it.’

  Yamanaka said, ‘True enough. We all saw the final self-rep experiment on the Moon. Well, it could hardly be concealed. But we think that was a crucial proving achievement. The engineers had to demonstrate to themselves, and to their superiors and political controllers, that this thing, their Acorn technology, worked, end to end, from the touchdown of one bird, the build, and the launching of two. Even if it revealed a lot of the detail of their project to the rest of the world.’

  Harry Regent put in, ‘I might say that we’ve long known the commercial logic of replicator technologies. We in the West, I mean. Sure, replicator tech was going to be expensive to develop – but once you had it, you could get an unlimited number of copies, for no more than the price of the basic resources anyhow. And then you could have a strategic advantage. You could use such technologies to take the high ground of Solar System resources, before the rest had a chance. If you were first in the game.’

  ‘Well,’ Yamanaka said, ‘even if they had been working on this stuff before Blink Day, in the end the Chinese didn’t play that game at all. Any variant of it. The Moon, it seems, was just a proving ground. As soon as their basic technology passed this final test, off went the two replicator ships, the Acorns, parent and child, off the Moon, back into space. Then to Mercury. A move that surprised us all. And then—’

  Zhi broke in. ‘There must have been some monitoring of their activities. Never made public.’

  ‘Only glimpses,’ Yamanaka said. ‘But that is why Harry and I are here.’

  Sara seemed suspicious. ‘Why? This is a project to construct an entirely different kind of spacecraft – and nothing to do with replication technologies.’

  Yamanaka glanced at Jones with a rueful grin. ‘I am presenting this badly. I apologise for any offence. You must understand this is not my . . . expected career path. I am a scientist rather than a diplomat.

  ‘Here are the facts you need to know.

  ‘Yes, in June of last year the first two Acorn craft left the Moon, and journeyed on a low-energy orbit to Mercury. We know they arrived in orbit around the planet after a hundred and five days – in late September last year. And we know that twenty-four hours later they landed, side by side, in a large feature known as the Caloris basin, a vast impact crater. And, in the year or more since then – well, we’ve seen very little. At first, anyhow.’

  Zhi thought hard. ‘What about satellites, probes? I know we had some deep-space inner Solar System probes, studying the Sun, Mercury. Ange Costello would know, that’s one of her specialities—’

  ‘Yes, but we had no functioning orbiters around Mercury itself,’ Yamanaka said. ‘They might have survived the Blink, when the Sun’s gravity suddenly switched off. The free-flyers, which were in solar orbit themselves, were scattered. Not entirely lost, but they have proved useless to observe Mercury’s surface in detail.’

  ‘And telescopes? Why, the L-Cubed-T here at the Lodestone—’

  ‘Was actually used for the purpose,’ Serena Jones admitted. ‘I had to keep it from most of the crew. Ange knew. Remember those Navy guys who came up here, supposedly to advise me on imaging technology to be used on Pioneer? Ange ran the experiments for us.’

  Zhi had known nothing of this. And nor, evidently, had Sara, given the way she stared now, open-mouthed.

  ‘Even so we have little more than blurred images of – scars – on Mercury’s surface,’ Yamanaka said. ‘From all such sources. We know what the Acorns do. They are replicators. We suspect they are busily replicating away down there – using Mercury resources rather than lunar.

  ‘That must be causing them to modify their technical strategy somewhat, by the way. Mercury is different from the Moon in many respects – a different mineralogy, for one thing. For instance, we think they are, umm, growing their solar energy capture panels with glass as a base, fused silicates, rather than aluminium as on the Moon. We can see the sprawl of such fields as they grow. On the other hand the available solar energy is much more intense on Mercury, so progress must be rapid.

  ‘But we can’t see.’ She clenched a fist. ‘I can’t tell the President what it is the Chinese are up to even day to day, let alone what the long-term goal is. And if it has anything to do with the Galaxias crisis.’

  Jones said, ‘Replicators on Mercury, though. That could lead to something big. That’s the point of replicators, in a way. From small beginnings . . .’

  ‘Hm.’ Sara tapped a pad. ‘So if the replicators reproduced at the same doubling rate as on the Moon – thirty-six days, right? – there might be a thousand installations up there by now. Even allowing for waste, failures. And even if their energy-capture blankets are scaled down from the Moon, given the higher intensity of sunlight at Mercury . . . the whole collection might span twenty, thirty kilometres. Ought to be very visible. And growing all the time.’

  Zhi thought back. ‘The conferences that have been held. When we announced this project, the Pioneer, an active way of, well, pushing back at Galaxias. There were the Chinese – my own government – preaching caution and patience, the way they believe Galaxias may be thinking too. Covering Mercury with replicators doesn’t sound too cautious or patient, does it?’

  Sara said carefully, ‘I suppose it does depend on the final goal—’

  But Harry broke in, speaking softly to Zhi. ‘It wasn’t just your government who’s been lying, pal,’ Harry said. ‘It was worse than that. It was your own mother. Who hasn’t seen fit to confide in you, has she? Even though she seems to have been central to the whole replication project. She didn’t get in touch even now, even though she must have known we were coming here.’ He shook his head. ‘Don’t answer that. I know she hasn’t. Because the security analysts told me so.’

  Serena, unexpectedly, drifted over to Zhi and put an arm around his shoulders. ‘I am sorry you have had to learn about this in such a way. This evident betrayal.’

  Yamanaka studied him. ‘And I too am sorry. We have known each other for some time. I had no way of discussing this with you in advance, Zhi, as you must understand.’

  Zhi shook his head – covering his reaction, as he pushed this latest hurt deep down inside. ‘I’m OK. As you have guessed, all of you, my relationship with my mother is complicated.’ He shrugged. ‘She has her goals, I have mine. It’s been that way all my life.’

  He was uncomfortably aware of Harry’s reaction as he spoke – a stare, hard, judgemental, calculating.

  Zhi said, ‘It will never change. But still, Prof Yamanaka, Sara’s question stands. What does this have to do with us?’