Xeelee Redemption

by Baxter, Stephen

  Since Larunda Station, where she had helped prepare Michael Poole and Nicola for their dive into the Sun in search of the Xeelee, Jophiel had thought of Asher as young. In fact she was in her sixties now; he knew she had started on her AS treatments, but was allowing herself to age with a grace that lent her authority. Since the split she had been the nearest thing to an astrophysicist on board the Island, making deep-sky studies of the structure of the Galaxy and the wider universe – studies from a viewpoint unparalleled in the history of mankind. Now she lifted her face to the apex of the lifedome – to a black sky, a scatter of stars – and one particularly bright light at the zenith, directly ahead on the line of the Island’s motion. Jophiel knew that even this view was artifice; the wormhole interface mounted on the top of the lifedome was in reality still there, a big blue tetrahedral frame, conveniently edited out of the visual field.

  ‘A starry sky,’ Asher said. ‘Where are we? Could be anywhere, right? Even after twenty years on this tub we still haven’t come all that far, in terms of our intended journey to the Core – only about a twentieth of that great distance. But it’s not quite like the sky of Earth. There are fewer stars visible to the naked eye, actually.

  ‘That’s because we are in a gap.

  ‘We have passed out of Sol’s local galactic arm, the Orion-Cygnus Arm. The next arm in is the big Carina-Sagittarius Arm, another three thousand light years deeper into the Galaxy. But, who knows? Maybe what we stopped for here will turn out to be more important than any of that. Depending on what we find up there.’

  She pointed at that bright zenith point.

  ‘We’re actually in the system of Goober’s Star already. Goober is a Sunlike star, more or less. We’re still a thousand astronomical units out. Too far out to see any inner planets, with the naked eye anyhow. But we’ve already passed through most of Goober’s Oort cloud, the big outer sphere of comet cores and rogue planets. And we’re only ninety days out from the inner planets, by GUTdrive, an easy one-gravity cruise. Close enough in for us to get a good look at what we’re walking into, to confirm the remote spotting, before we commit ourselves.

  ‘But we have to assume that whoever is in there – whoever sent those messages Gea detected – already knows we’re out here. That they saw us coming. We would have seen a GUTship coming into the Solar System from interstellar space.’

  ‘We always knew complete stealth was impossible,’ Nicola said with a trace of impatience. She had had a lot of input to this stage of the flight plan, Jophiel knew. ‘Yes, they probably know we’re here. By pausing here, all we tried to do is buy a little breathing space. And besides, we didn’t come here to fight. We’ve got neither the equipment nor the intention. So maybe those who are watching us might see our hanging around out here and not bristling with weaponry as a peaceful gesture.’

  Asher kept staring up at the star itself. ‘Anyhow, that’s where the action is. But I can tell you already that I don’t like it.’

  Jophiel frowned. This was new. ‘You don’t like what? The star? What’s wrong with it?’

  Asher shrugged. ‘We’ve known for a while that this is a G-class star, like the Sun – like it but not identical: the star is G-zero where the Sun is G-two, a little bigger, a little brighter. No companion stars. Well, now we’re observing Goober’s Star up close, and we’ve sent out probes to reconnoitre the rest of the system. And we’re seeing signs of variability about the star. Magnetic storms. Huge flare events. If I didn’t know better I’d say that star was close to going nova.’

  Jophiel sensed the crew’s stir of alarm. ‘But you do know better. Right?’

  ‘A nova is what you get when a star has got a companion, close in. The companion star dumps material, dragged out by tides, onto the surface of the heavier star. A layer of hydrogen builds up until it’s dense enough to start a fusion reaction, up there on the surface, and – wham.

  ‘So, in such a double system, you would see this kind of precursor event, storms and flares, as the principal star prepares to blow. But here, it’s an anomaly. No companion, you see. We don’t know what’s causing the flares, but what I’m seeing does seem to be related to a disturbance of the outer layers of the star. Just like a nova star. I guess we’ll learn more when we get further in.’

  Ben Goober stepped forward, with a glance at Jophiel. ‘Maybe I could add to that.’

  ‘Go ahead, Ben.’

  ‘Officer Fennell, you say you don’t like the look of that star up there. Well, I was tasked at looking at where we are right now, this Oort cloud, the Kuiper belt closer in. And I don’t like the look of those two features either.’

  ‘Show us.’

  Ben Goober raised his hands and threw Virtuals in the air: a pinpoint star, wide circles around it that were the orbits of planets. He began to go into a lot of detail about the long-term evolution of the motions of families of minor bodies. He was no longer a kid. But, in his thirties, nervous, shy, though evidently intensely bright, he was a much less impressive speaker than Asher Fennell. The crew fidgeted.

  When he started to run down, Asher helped him out. ‘So, if I can sum that up – the orbits of many of the objects in the Kuiper belt, even in the Oort cloud, look as if they have been adjusted. Yes?’

  Goober nodded vigorously. ‘Heavily regularised. The ellipticity ironed out. It wouldn’t necessarily be a difficult thing to do, if you had the resources and the time. There are some big objects out here, but they move slowly. You could fix the trajectory with targeted detonations, or GUTdrive engines mounted at the poles, or just with a series of flyby gravitational assists. Multiple tweaks, until you got what you wanted.’

  Jophiel thought he saw the pattern. ‘Which is what?’

  Goober shrugged. ‘Safety, sir. Domestication. Out here is where the comet nuclei orbit. Back in the Solar System we had Spaceguard, for – umm—’

  ‘A couple of millennia,’ Asher put in.

  ‘We were watching for rogue objects straying into the inner Solar System that might strike the inhabited worlds. We actually pushed away a couple of them. Here that process of safeguarding has gone a lot further. Somebody came out here and tidied it all – made it safe. And it was a big job, sir. Sol’s Oort cloud reached halfway out to Alpha Centauri. Deep sky with a lot of objects. Same here. Must have taken time, but they did it.’

  ‘A lot of time,’ Nicola said now. ‘Which fits in with my own report.’

  Jophiel nodded permission for her to speak.

  Nicola was by profession a pilot, but she had been a warrior – she’d fought the Xeelee itself as it had first neared Earth-Moon space – and with Max Ward still on the Cauchy, she was the nearest to a military mind to be found aboard the Island. Everybody hoped this system wouldn’t become a battleground. But it seemed remiss not to prepare for the worst. So Jophiel had set Nicola the task of preliminary surveillance.

  Now brisk, efficient, even impatient, she hurried through a blizzard of visuals of her own, cast in the air above the heads of the crew: a plan view of the inner Goober system, the neat circular orbits of planets.

  ‘We’ve identified seven inner planets,’ she began. ‘Goober a to Goober g. Some have moons. You know how it is; the outer edge of a system like this is fuzzy, with plutoids, ice worlds, wandering in from the inner regions of the Kuiper belt. The innermost worlds are where the action is anyhow . . . What’s the first thing you notice, by the way?’

  ‘Neat circular orbits,’ said Ben Goober.

  ‘Right. Very low ellipticity, for any of the orbits. We suspect there has been conscious adjustment, as with your Kuiper and Oort objects, Ben. Also, notice no asteroid belt, unlike in the Solar System. There are asteroids, but they all seem to be in stable locations – such as the Trojan points of those Jovian worlds you can see. Safely tucked away. Anyhow, seven planets. All with their own anomalies, I should say in advance. The innermost, a rocky planet, Mars-sized, orbit
ing about where Mercury is in our Solar System. Or was.’

  Jophiel shrugged. ‘What’s anomalous about that?’

  ‘Too light,’ she said simply. ‘Not dense enough. We can calculate the mass if there’s a moon, or as in this case by gravitational deflections of the other planets—’

  ‘We believe you,’ Jophiel said.

  ‘The whole thing has a density of silicate rock, all the way down. No metallic core.’

  ‘Earth’s Moon was like that,’ Asher said. ‘That was a relic of a big impact which splashed up rock from the mantle of a big proto-Earth. Could this be an impact product?’

  ‘We don’t think so,’ Nicola said. ‘We think it was mined out.’

  ‘Mined out. How? What makes you think so?’

  ‘Anomalous surface features,’ she said bluntly.

  Now she displayed slightly fuzzy, heavily magnified images. Jophiel made out a very lunar landscape, airless and stark, brightly lit by the nearby star. Craters of all sizes, circles overlapping. And a series of big rectangular cuts in the ground, deeper than the light could reach.

  ‘Lethe,’ Asher said. ‘How long would it take to mine out the entire core of a planet?’

  ‘About as long as it might take to fix the Oort cloud, like Goober told us. Next.’

  Jophiel glanced around at the crew, who were watching intently. He briefly wondered what was going through their minds, as for the first time they saw these worlds which were, he supposed, likely to become their home – or their battleground.

  Goober b was a planet about the same distance from the parent star as Earth was from Sol. But, in Nicola’s image, Jophiel saw only a white glare, with faint suggestions of shadows, like high clouds. And a hint of something else. At the limb of the planet, the visible edge, what looked like some kind of reflection, a curve mirroring the horizon – tens, hundreds of kilometres high . . .

  Somebody called, ‘It’s where Earth should be. Looks more like Venus.’

  ‘That’s about right,’ Nicola said. ‘This world has suffered a runaway greenhouse. Just like Venus, all the carbon dioxide baked out of the rocks and suspended in the air, trapping the heat. Goober’s Star is about ten per cent more luminous than Sol, which might explain why this world went bad.’

  Jophiel sensed an unspoken clause. ‘Or? What else?’

  ‘War. We don’t know what’s down on the surface. But we have found artifice here.’

  ‘That roof,’ somebody said. ‘Over the horizon – you can clearly see it.’

  ‘You have sharp eyes,’ Nicola said, looking for the speaker. ‘How’s your flight experience? See me later . . .’ She pulled up a relevant image: that fine arc, seen edge on, hanging over the planet’s horizon. ‘We think this is a relic of a shell. Like an arcology dome, but one that once enclosed the entire planet. There are other scraps left, in orbit, standing on immense space-elevator pillars. With a shell like that you could contain an atmosphere; you could shield out solar flares and other nasties, reduce the sunlight from that hot old star out there . . . A very dumb technology that becomes smart if you scale it up.’

  ‘But it’s broken,’ Jophiel said evenly. ‘Think how long it would take to build such a thing. And then—’

  ‘Think how long it would take for it to fall apart to this extent.’

  ‘This is an old system,’ said Ben Goober. ‘Old, engineered, worked out.’

  ‘That’s the impression we’re getting,’ Nicola said. ‘Monumental ruins. OK. Goober d—’

  ‘Hey,’ Jophiel protested. ‘What about c?’

  She grinned at him. ‘Saving the best to last.’

  Goober d, like e, f, and g, turned out to be a gas giant. None of the quartet was as large as Jupiter. There was no trace of mega engineering to be seen here, Nicola said, but still, it was clear intelligences had been at work.

  ‘Resource depletions,’ she said. ‘Of fusion-friendly helium isotopes. Of exotic hydrocarbons in the upper atmosphere. Possibly even of metallic hydrogen from the planets’ cores. And maybe other stuff we’re not recognising. Everything we can think of that we’d find useful is in anomalously short supply. Maybe they even mined the magnetic fields for energy, the way you used Io and Jupiter to build your wormholes, Jophiel. Or anyhow Michael did.’

  ‘But still, to have caused lingering, visible depletions on the scale of a gas giant—’

  ‘Takes a long time,’ Ben Goober said. ‘A lot of resources extracted. That’s the theme of the whole system, isn’t it? It took a long time to get this way.’

  ‘It needn’t be the Xeelee, by the way,’ Asher said. ‘We’ve travelled a long way in human terms, but we’ve only taken baby steps into the Galaxy. We’ve only encountered two intelligent species – the Xeelee and the Wormhole Ghost – and they came to us. But there’s every reason to think that there must be many races out there – or, there were.’

  She looked around at her crewmates, and Jophiel wondered if she was wary of giving too bleak a perspective. ‘The universe isn’t young, you see. Nor is the Galaxy. Most of our Galaxy’s stars have already been born, and we’re latecomers to the party. Chances are there have been many races, come and gone, of builders and technologists whose ruins we might see, and others who left no trace at all, back to the earliest days of the universe. In fact we believe that the Xeelee is a relic of a very early era, just after the Big Bang itself.’

  Jophiel said, ‘So this may be typical of what we’ll find. Vast ruins, worked-out mines.’

  ‘Maybe,’ Nicola said, and she grinned. ‘But what’s not typical of this system is that we heard that human signal.’

  Jophiel had to grin back. ‘And you’re about to tell us the location that signal came from?’

  ‘As far as we can tell—’ She waved a hand, and the image of another vivid world coalesced above her head. ‘Goober c.’

  Jophiel could see at a glance that this was a much more complex world than its siblings.

  And that it was alive. Or anyhow it looked that way.

  Evidently a big world, but rocky, like Earth, not a giant of gas or ice. The atmosphere was neither entirely transparent, nor entirely opaque: it was cloudy, misty, elusive. In places higher ground seemed more clearly visible, as if pushing out of that murky air. Chains of huge mountains crossed ragged continents. Perhaps there were oceans, Nicola said. The gleam of ice-white stretched far from each pole. And, in places, Jophiel thought he could see grey-green. Life?

  Two moons hung in the sky, apparently bare, sunlit rock.

  Asher took over. ‘You’re looking at a super-Earth. Significantly more massive than Earth. Forty per cent higher gravity. It won’t be comfortable down there . . . Actually, more strictly, it’s like a super-Mars. Even though Goober is more luminous than the Sun, Goober c is twice as far as Earth is, was, from the Sun, and the planet gets only about a third of the sunlight Earth received. Less than Mars itself. But the surface is warmer than Mars. Not from the sunlight, but because the planet’s that much bigger, with much more residual heat. And it’s kept more of an atmosphere. That blanket you can see is surprisingly thick. It contains about five times the mass of Earth’s atmosphere in carbon dioxide alone.’

  ‘And so there’s a strong greenhouse effect,’ Jophiel guessed.

  ‘Correct,’ Asher said.

  ‘Enough to make this world habitable? Mars had its Lattice. It had life. But nothing so obvious as Earth life – too cold, too dry – nothing like that.’ He pointed at the greenish patches.

  ‘That does seem to be life, yes. There’s a kind of photosynthesis going on – but the native algae or plants or whatever are splitting carbon dioxide and the local rocks to release hydrogen, not oxygen. We’re guessing this from what we can measure in the air; we can figure it all out when we get close up. As far as we can tell, down there the air is as thick as a shallow ocean, and you’ll need oxygen tanks to bre
athe. But at least it’s warm.’

  Nicola grinned. ‘And, Jophiel – here’s the big reveal. Down in those deep valleys—’

  ‘What?’

  ‘Hull plate.’

  Jophiel felt cold. ‘Xeelee technology?’

  ‘Right. Swathes of it, blanketing the landscape. No other Xeelee signature – no discontinuity-drive gravity waves, no planetbuster energy leakages. But, yes, they’ve been here, at least. We don’t know what this means.’

  Jophiel said, ‘But whoever sent those messages, with the human content, is still down there—’

  ‘Correct.’

  Jophiel, like most of the crew, flinched, startled. The voice, deep, gravelly, without inflection – mechanical – had seemed to boom from the sky.

  He looked up.

  A silver sphere hung in the air, above all their heads, eclipsing the pinprick glow of Goober’s Star. A couple of metres across, perhaps. Evidently massive.

  Somebody shot at it. Jophiel heard the crack of the release. What looked like a staple sailed without deflection through the gleaming carcass of the intruder. There was no evident wound, no damage. Some kind of Virtual, then?

  Jophiel glared around to see who was responsible.

  A young crew member was holding up a staple gun.

  Nicola moved first, grabbed the gun from the crewman. ‘That thing’s no more real than Jophiel over there. Good job too. No more assaults, unless authorised.’

  Now the crew began to speak up.

  ‘But that thing’s inside our lifedome, even if it just got projected in here—’

  ‘I know that thing, I saw the recordings from Jupiter space—’

  ‘That’s a Wormhole Ghost—’

  ‘Which of you,’ the visitor thundered now, ‘is the Poole?’

  The crew fell silent.

  Nicola and Asher instinctively moved to Jophiel, as if to shield him. Just as instinctively he tried to push them away. He ended up walking through their bodies, with sharp pains from consistency-violation warnings.