Poseidon's Wake

CHAPTER TWENTY

Kanu prepared chai and knelt by Nissa’s skipover casket until with a gasp of pressure the lid opened and slid back. She lay there, alive but not yet awake. He allowed that to happen in its own time, still kneeling, until the awkwardness of his posture became almost too much to bear. Still he waited. At last she stirred, her throat moving, her eyes opening to slits. Again he allowed her silence, although he was certain she felt his presence, breathing next to her.

Eventually she swallowed and said, ‘Where are we?’

‘Our destination,’ Kanu answered. ‘The Gliese 163 system.’ He spoke slowly, calmly, with as much gentleness as the words allowed. ‘We’re about six light-hours out — close enough for a good look at all the planets. I felt you should be awake for this.’

‘Why?’

‘It’s your right.’

After a silence, she said, ‘I haven’t got any rights, Kanu. I stopped having rights when I was kidnapped. I’m a hostage. A prisoner. Baggage.’

‘I’m sorry things happened the way they did.’

‘Then that makes it all better, doesn’t it.’

‘I mean it. I mean it more than you can know.’ Kanu searched his thoughts, wishing there was a way to make her see his good intentions, the vastness of his regret. ‘I wronged you, we both know that.’

‘Do you?’

‘I lied to you and I used you. My not being aware of it… that was never an excuse. Not when I planned it all in the first place, certain of how it would play out — us meeting, you having the ship, getting me to Europa, then going our separate ways.’

Her voice was a rasp. He remembered how dry his own throat had been, coming out of skipover only a few hours earlier.

‘And next you’ll say you had no choice, that it had to be done.’

He ran a hand across the cold skin of his scalp, shaved before skipover. ‘If I said as much, it would still be no excuse. I should have found another way — another means of reaching Europa. It was just that you presented the least risk of detection, and—’

‘There you go again.’

‘I am sorry.’

‘This is your way, Kanu. You’ll always have a justification, an excuse. There’s no action you can’t explain away. It’s always necessary, always the only thing you could have done.’

‘I will try to do better.’

‘It’s a little late for that, wouldn’t you agree?’

‘I will hold my hands up and say that everything I led you to believe after Lisbon was wrong. But this was never my intention. I didn’t want you on the ship.’

‘Out of sight, out of mind? You’d use me, but at least I wouldn’t be hanging around afterwards, reminding you of the fact?’

‘If that’s how it feels to you, I apologise. Do you remember much of what we talked about before skipover? This was the Margrave’s doing. He wanted to protect you, and I told him to do whatever was necessary. I didn’t think that meant capturing you and your ship and smuggling them aboard my own!’

‘Give me back my ship.’

‘It’s yours, whenever you want it. But we’re fifty light-years from Earth. Fall of Night would be lucky to make it to the edge of this solar system, let alone get you home.’

‘Then I’ll die trying. Better that than this.’

‘It’s normal to be a little fatalistic after skipover. You’ll start to feel differently when you’ve been up and about for a bit.’

‘Don’t tell me how I’ll feel, Kanu.’ A notch of suspicion formed on her brow. ‘Why are you awake before me, anyway? You promised we’d come out together.’

He nodded. ‘I did, and I’m sorry that promise was broken. Swift… thought it might be better this way.’

‘That’s useful, then. Blame everything on Swift.’

‘I regret that, like so many other things. But I’m not sorry that you’re here, that you’re with me.’ He shifted on his old, old knees. ‘It’s something marvellous, Nissa — something that eclipses anything that happened to me in my old life. I want you to see it, to share in the discovery — to be a part of this.’ He paused. ‘We’ve found… well, you really should see it for yourself.’

‘Nothing’s going to make this better, Kanu. The sooner you accept that, the easier it’ll be for both of us.’

‘I brought you chai,’ he said, with a certain finality. ‘I thought you might like some.’

‘Chai doesn’t make everything better. You know that, don’t you?’

‘I do,’ Kanu answered.

When he was satisfied with her progress, Kanu returned to the control deck. Nissa was free to follow him there — he hoped she would — but she would have to make up her own mind about that. The displays and readouts were all still active, as he had left them: schematics and close-ups of various aspects of the system and the ship. The largest was a series of nested ellipses, marking the orbits of the worlds around their parent star. Taking his seat, Kanu refreshed the display. One by one, the globes of planets popped onto the image in their current orbital positions. They were shown at a scale much larger than their orbits, but their relative sizes were preserved. Next to each was a column of names and data.

Even the smallest of these worlds had been detected and characterised centuries ago and in most cases subjected to direct imaging of surface features. Still, even the mighty Ocular had not been able to study every single planet around every star, even in the local stellar neighbourhood — there were simply too many candidates. Gliese 163 lay further away than many of the better-studied solar systems, beyond the reach of the holoships, and so there had been no incentive to obtain more accurate data. Beyond the star’s habitable zone was a barren, Earth-sized planet. Cold and nearly airless, it would not have merited his attention except for one thing. On the planet’s face, sweeping around into view as it rotated, was another Mandala.

It was same size as the alien structure on Crucible, different in its details but unquestionably the work of the same intelligence. In those first few waking hours, Kanu had stared at it in wonder and a kind of stupefied bewilderment, astonished that it should fall on him to be the first to witness and document this discovery. It turned out that it was visible, in ghostly form, in the Ocular data. But the resolution had not been quite sufficient to reveal it for the thing it was: an artificial blemish rather than the work of nature.

Now a question occurred to him. It was one thing to accept Mandala as a singular phenomenon, but if there were two of them, then there were probably others.

How many more?

He laughed. He had no idea, beyond the instinct that two were not sufficient. The Mandala Makers would do things in threes. Or fours. Or multitudes.

‘Out of your depth already, merman,’ he said to himself.

‘I might venture that we are all equally out of our respective depths,’ Swift said, standing several metres to Kanu’s right, stroking his chin in idle fascination as he studied the new images. ‘There is no precedent for this. Well, exactly one precedent — the other Mandala. But we know so little about that, we are scarcely on firmer ground than if we had never seen anything similar. Would you care to take a closer look at it?’

‘Definitely. But no matter what course we set now, we’ll have to swing around the star first. What about that heavy planet, further in? Looks as if our present course will take us quite close.’

It was the largest world that was not a gas giant, and it orbited Gliese 163 once every twenty-six days. That was a ludicrously short ‘year’ by any measure, but the star was a red dwarf — cooler and smaller than Earth’s sun — and such a tight orbit placed the big planet well within the bounds of habitability. It had been given a name: Poseidon. There were other Poseidons, Kanu knew, and he would be unwise to attach undue significance to such a thing. But given the history of his family and their long and tempestuous involvement with the people of the sea, it could not help but feel apt.

More than that, Poseidon was a waterworld. Its mass was higher than Earth’s, and it was also larger. Oceans blanketed it from pole to pole, with no dry land anywhere. Indeed, those oceans were far too deep for any features to have pushed their way through to dry air. Warm at the surface — uncomfortably so — the oceans plunged down through endless black kilometres, finally becoming cool. Animals could survive in those clement depths, but they would have a hard time thriving in the surface waters.

Which was not to say that there was no life at the ocean’s upper extremity. From space, the blue of the dayside ocean was broken by smears and swatches of green, ranging in size from tiny islands to expanses with the area of terrestrial continents. It only took a few scans to establish that these features were vast floating structures, rising and flexing with the ocean’s solar tides rather than having the waters lap over them. From this distance, they looked as thick and dense as forests. But in fact the living mats were tenuous, seldom more than a few centimetres thick and subject to a constant process of shearing and re-formation — no more substantial than rafts of floating seaweed or kelp. They were an explanation for the free oxygen in the atmosphere, but it was hard to see how anything built on them would not break through into the underlying water.

Nonetheless they were an example of a rich alien ecology, and Kanu would have looked forward to gathering more information were it not for the other things on Poseidon. Icebreaker was imaging them clearly, and they were an affront to everything Kanu thought he knew about planets.

There were arches in the ocean. Dozens of them, dotted all over the visible face, always in open water rather than cutting up through the green swatches, and they rose so far that their tops vaulted out of the atmosphere and into airless space, a hundred kilometres above the sea. He stared at them for long minutes, convinced — despite himself — that they had to be an excusable analytical error, a figment of the ship’s confused sensors.

But the harder Icebreaker looked, the more real the arches became. They were not phantoms.

They were solid entities, casting measurable shadows across a continent’s worth of ocean. Each arch had a shallow rim and a flat face like the tread of a wheel. They gave off a radar backscatter suggestive of metals — the only hint of metals anywhere on Poseidon.

‘What are they?’

She might have been standing behind him for as long as he had been staring at the arches — so absorbed was Kanu in their mystery that he had not noticed Nissa’s arrival on the command deck.

He angled around in the chair. ‘I don’t know. They’re not the thing I mentioned — the thing I wanted you to see. How are you feeling?’

‘If I wasn’t well, the casket wouldn’t have let me out of skipover.’ But perhaps that reply was harsher than she had intended. ‘I’m all right. Sore, stiff and very thirsty. I’ve never done this before. My head feels cold. I’ve never had it shaved.’

‘Nor me,’ Kanu said. ‘And I feel the same — or did, anyway. But a few hours up and about seems to help.’ He pushed aside the console so he could stand. It did not feel right to sit while Nissa had to stand.

‘No, stay where you are,’ she said softly. Not an order, but a clear expression of her feelings. She was here out of curiosity — a need to know what was in store — but nothing had been forgiven, and he should not presume she would put aside her grievances any time soon.

‘Artificial structures,’ Kanu said, just as softly. ‘No one’s seen anything like those before, here or anywhere else. They’re still a bit hazy at this range, but our approach will take us a lot closer to Poseidon.’

‘You said this wasn’t the thing.’

‘It isn’t — although right now I’m not sure which is the more amazing discovery. The eighth planet out — let me get an enlargement up. It has a name, too — Paladin — and a circular orbit, about half an AU, which swings it around Gliese 163 in just over two hundred days. It’s Earth-sized, but much too far from the star to be habitable.’

Nissa waited until Icebreaker had projected its best image of Paladin onto the screen. She looked at it in silence for a few moments.

‘I’ve seen something like that before.’

‘We all have. It’s like the structure on Crucible — another version of the same thing. Can you imagine how significant this is? It’s more than just another Mandala. It tells us — begins to tell us, anyway — that there has to be something more to Mandala. A deeper significance than anything we’ve worked out so far.’

‘How so?’

‘The M-builders wouldn’t have gone to the trouble of making two of them if it didn’t mean something. And now that it turns out there are two, I think there must be more. Dozens, hundreds — who knows? We’re just beginning to push into true interstellar space. There are hundreds of billions of other solar systems out there — maybe there are billions of Mandalas!’

‘All right, it’s something.’ Her voice was flat, unexcited. He wondered if that was her genuine response, or whether she was consciously damping down her enthusiasm as a kind of punishment.

‘It’s more than something! Now at least we have some idea why the original transmission was aimed at Crucible, not us.’

‘Do we?’

‘Well yes, obviously. It’s something to do with the two Mandalas — the two versions of the same structure.’

‘I hope that isn’t the best explanation you’ve got.’

Kanu was starting to feel needled now, but he fought to keep any sign of it from his response. ‘It’s not much, I know — like I said, I was only awakened a little earlier than you, so I’ve barely had time to take any of this in, let alone think about the implications. And that’s why I’m so glad to have you here!’

‘And why would that be?’

‘Two heads, Nissa! I’m a diplomat, not a scientist. I don’t have the background to begin to do this justice.’

‘And you think mine’s any more qualified?’

‘I was married to you for long enough to know that you can turn your mind to just about anything if it interests you. Deep down, I’m not very imaginative. You are.’

‘It’s a bit late to start trying to turn my head with flattery.’

‘That’s not my intention. I just want you to feel valued. You can see your being here as a mistake, or you can see it as an opportunity, a chance—’

‘I’ll decide how I see it, thank you.’

‘I didn’t mean it like that.’ But he knew that no choice of words was going to dig him out of this hole. It was largely of his own making, too.

Nissa was still standing, one hand cocked against her hip — her entire posture conveying scepticism and an unwillingness to be persuaded.

‘So what have you done with this news?’

‘Nothing at all. I started composing a message about the second Mandala — I didn’t even know about the arches at that point. But I thought about you and decided against sending it.’

‘Why?’

‘Because it would be selfish of me to act as if the discovery were mine alone.’

‘You made it.’

‘That was just happy accident. Now that you’re awake, though, I’d like you to share it. I won’t transmit the news, not until you’ve had a chance to see all of this for yourself and decide what we say.’

‘Such nobility.’

She had meant the words sarcastically, but he decided to take them at face value. ‘It isn’t, and I know it. But if I can do anything to make amends…’ Then he shook his head. ‘I can’t, I know I can’t. And I don’t expect your forgiveness.’

‘Finally.’

‘But what I said is true. I value you, Nissa — and you should value yourself. Regardless of how we got here, who wronged whom, we’re here.’

‘And the prize for most tautologous statement goes to—’

He raised a hand. ‘I know. But I mean it — we are here. In this moment, experiencing this discovery. This is a place no human eyes have ever seen. Where no man has gone before — who said that — William Shakespeare?’

‘I’ve no idea.’

‘The point is, it’s just you and me. And we have responsibilities now, whether we want them or not.’

‘I’m clear about my responsibilities,’ Nissa said. ‘You don’t need to spell them out for me.’

‘That was never—’

‘Poseidon. How close will we get?’

‘About five light-seconds — there’s scope for adjusting our course if we want to skim nearer. We’ll have a steadily improving view of the arches as we approach — and of anything else on or near Poseidon. Mainly, I want to find the sender of that signal.’

‘If they’re still here.’

‘Icebreaker’s been transmitting its arrival for weeks, long before we were woken, and listening for a response. So far it hasn’t heard anything, but that doesn’t mean we won’t find something when we get closer.’

‘The bones of whoever sent it.’

‘I sincerely hope it’s more than bones.’

After a silence, she said, ‘I want to know it’s you. You and not the robot.’

‘It is me.’

‘Are you sure of that?’

‘Swift is in me, but I’m not Swift. And when you speak to me, it’s Kanu. The man you were married to. The man who still wishes he hadn’t dragged you into this. The man who wishes he was back in Lisbon, and happy to have found you again.’

He braced for a cutting response, but this time his words drew no venom.

‘Are you in control of the ship, or Swift?’

‘Me. Only me. Swift won’t take over my body without my permission — my authority.’

‘Are you sure of that?’

‘Yes.’ But he answered with more surety than he felt. What else could he do, if he were not to undermine Nissa’s already fragile confidence in their situation?

But perhaps she knew he was lying. ‘Good,’ she answered, with a coolness of tone that said she had seen right through him. ‘Let’s try and keep it that way, shall we?’

Kanu nodded. It was a small thing, but he would take what he could.

Days and weeks brought them nearer to Poseidon. The improvement in knowledge was steady rather than dramatic, their view of the system gradually sharpening and gaining detail and texture. After the initial discovery of the second Mandala and the arches there were no great surprises, just reinforcement of what they already knew. The Mandala was definitely real; the arches were definitely not of natural origin.

Beyond that there were hints of further interest, but nothing that answered Kanu’s central question: who or what had need of Ndege Akinya?

Paladin had a very small moon. That was not unusual in itself, but this misshapen little body was odd in a number of ways. It was too warm, for a start: much hotter than would be expected given the standard thermal equilibrium for something in its orbit and distance from Gliese 163. Kanu wondered whether the rock might have been an asteroid, or the remains of one, captured after some violent collisional process. Such an encounter would have needed to be recent enough that the thermal energy of the event was still bleeding away into space.

It became even stranger, though, because in addition to the overall temperature of the rock, there were a handful of even hotter regions on its surface. They were like the infrared traces of fingerprints left on an apple held in a human hand. They were hot enough — up in the three thousand kelvins — that they made him think of geysers or volcanic outflow points. Strangely, though, there was no trace of material boiling away into space.

What was making those hot spots glow? Were they natural features or evidence of deliberate activity? He had been aiming transmissions at the rock but nothing had come back from it. Kanu knew he would need to take a closer look, if for no other reason than to satisfy his curiosity about the peculiar heating effect. But that would be no inconvenience since he would want to examine the second Mandala in any case.

Closer to Poseidon, they found a secondary mystery. The arches were numerous and tantalising and definitely warranted examination. But lacing Poseidon — orbiting at different inclinations, in the manner electrons were once thought to orbit the atomic nucleus — was a host of small dark moons. They buzzed around Poseidon like flies, shell after shell of them. There had been no hint of them in the Ocular data, but that was to be expected. Dark as night and much smaller than the planet, they would have been almost impossible to resolve in time-averaged exposures, even when they passed across Poseidon’s visible face.

Clearly, they were not natural. Even if the moons were natural in origin — and their uniform size, shape and reflectivity suggested otherwise — they had most certainly not fallen into these orbits by chance.

The moons’ orbits ranged in diameter. The smallest nearly skimmed Poseidon’s atmosphere, almost down to the tops of the arches, while the widest spanned a distance of ten light-seconds. Between these extremes lay another fifteen shells. There were forty-five of these tiny moon-like objects in total, but no natural moons.

Kanu’s instinct was to avoid them. But they threshed around Poseidon in perfectly repeatable patterns, tracing staunchly Newtonian paths like marbles in grooves. Clearly their individual masses did not perturb each other, or the effects had been allowed for in some way. He could already calculate their positions to many centuries hence and be confident of his predictions. Threading Icebreaker through the weave of moons was a trivial matter: there were countless viable trajectories. The hard part would be choosing which he preferred; how close he was prepared to get to the world and to any one of its moons.

There was time to think it over — and of course it would not be a decision he took alone.

Nissa remained distant, offering no hint of imminent forgiveness. But her anger had softened to the point where they were able to have mostly cordial exchanges, even if there remained an underlying and unresolved tension. They kept themselves to themselves, occupying different bedrooms. Icebreaker was not a large starship, but there was space enough for privacy.

They did manage to put aside their differences long enough to eat together. They sat opposite each other, in high, stiff elephant-carved dining chairs, in a room set off from the control deck. Sometimes they ate in silence or with some musical accompaniment, often very old recordings. Occasionally the walls displayed moving images of African landscapes at dusk, skies like flame, trees like dark paper cut-outs against that brightness.

‘With your permission,’ Kanu said one evening, ‘we’ll take a closer look at Poseidon.’

‘Permission?’

‘Wrong word. Mutual consent. If you agree it’s the right thing to do.’

Nissa was silent. Kanu knew better than to press her. He studied her face, her eyes averted from his gaze — as if the act of eating demanded her total concentration. He still loved her. The more she pulled away from him, the more he wanted her. He thought of gravity, of inverse squares and the swarm of moons girdling Poseidon.

‘You’d have to be a corpse not to be interested in those arches,’ she said eventually. ‘That doesn’t mean I’m enthusiastic, or that I like this situation.’ She ate on. ‘I just want to know as much as possible, given that my survival may depend on the choices we make.’

‘I feel similarly.’

She shot him a sceptical look. ‘Do you?’

‘On one level, I’m terrified of that planet. It’s too huge — and those arches? They’re a slap in the face, a boot crushing down on human ambition. But I want to know what they’re for. I want to see them up close.’

Nissa poured herself a glass of wine, steadfastly omitting to charge Kanu’s glass at the same time.

‘There’s a Mandala on that other planet.’

‘Paladin.’

‘And arches on Poseidon. They don’t look alike, but I suppose they both require a technology beyond anything we have. Do you think they were put there by the same culture?’

‘No clue, but I’d like to find out. My guess? There’s a connection. To those moons, too.’

‘And what about the chunk of rock orbiting Paladin that Icebreaker can’t explain?’

‘I don’t know. It doesn’t appear to fit. The other things are recognisably alien — Mandala, the arches, maybe the land masses on Poseidon, the forty-five moons in those weird orbits. This is just a lump of rock that’s slightly too warm. I scanned it with radar, too — some metallic backscatter, but it’s different in composition from the arches’ signature. It could just be mineral deposits baked onto the surface — you’d have to ask a geologist.’

‘But you don’t think so.’

‘I think it’s something else that doesn’t belong, but which is different in nature from the other things. This system is strange enough that we’d have sent an expedition here sooner or later, so why would it not have interested other civilisations? Maybe we’re not the first explorers.’

‘There’s something missing, though. Something that ought to be here but isn’t.’

‘I had the same thought.’

‘Where are the Watchkeepers?’ Nissa asked.

Icebreaker’s planned course took them into the thresh of moons, slipping through their paths halfway between Poseidon and the highest orbit of its satellites. The trajectory would provide an opportunity to look at the moons in closer detail, but Kanu’s chief interest lay in the arches, rising from the ocean like the glimpsed coils of sea serpents.

Slowly their view of the arches improved. Only the tops were free of atmosphere, but much of their height was in extremely tenuous air, offering little obstruction to Icebreaker’s sensors. The arches were semicircular, rising one hundred kilometres from the ocean’s surface — identical in every dimension to the limit of Icebreaker’s measurements. Beneath the water there was a hint of continuation, a suggestion that the arches were in fact only the visible portions of half-submerged wheels, but that was as much detail as they could discern from space.

If they were wheels, then their treads were a kilometre wide, very narrow in comparison to their heights. Their rims were also about a kilometre thick, and there were no spokes or hubs. The arches — wheels, perhaps — were made primarily of some pale grey non-metallic substance, presumably possessing immense structural strength. From deep space, Icebreaker had detected the radar backscatter of metals, but this turned out to be a kind of ornamentation or embellishment added to the surface of the wheels. Cut into the rim and the treads, inlaid or recessed, perhaps even as a bas-relief — it was impossible to tell from space — was a suggestion of dense metallic patterning. To obtain a clearer, more detailed view, they would need to get much closer than five light-seconds. Icebreaker was not meant for atmospheric flight, but it could land on top of one of the wheels, which in turn would give them indirect access to the surface. Other than Fall of Night, there was nothing aboard Icebreaker that could serve as a shuttle, lander or re-entry vehicle — at least nothing with the capability of returning. If their other options were exhausted, there were single-use escape capsules which ought to be able to make it down to Poseidon’s seas.

But not now. This was a first pass, a scouting expedition. When they gained a better look around the system, identified the origin of the signal and found water ice to convert to hydrogen, which would in turn feed the initialising tanks for the PCP drive and guarantee them a trip home — then they could think about taking a closer look at the wheels.

‘We need another word for them,’ Kanu mused. ‘“Wheel” isn’t big enough. Worldwheels, perhaps. Do you like that? The Worldwheels of Poseidon. Has a certain ring to it.’

‘Whatever you think.’

‘I think this is wonderful and terrifying, and I wouldn’t miss it for a heartbeat.’

‘You came here to aid the robots, not to sightsee. Don’t forget the real reason for this trip.’

He smiled, still in the happy rush of discovery. ‘How could I?’

‘And what does Swift make of all this?’

‘Swift is all intellect — brilliant and fast. Swift by name, Swift by nature — but Swift doesn’t actually know very much. There wasn’t room in my head for him to carry a universe’s worth of wisdom — I carry my memories, my life experience. Swift can draw on my knowledge to some extent, sample my memories, but mainly he’s here to serve as witness, to guide my interpretations and actions.’

‘You haven’t answered my question.’

‘Swift wonders if machines made the wheels. The worldwheels. And Swift wonders if that would make them gods.’

‘So your friend has begun to turn to faith? I’d watch him carefully if I were you.’

‘Robots are entitled to ask the same questions as the rest of us,’ Kanu said. ‘There’s no law against it.’

Soon they were inside the orbit of the moons, still moving at a hundred kilometres per second.

The forty-five moons were all alike as Icebreaker could tell: each a perfectly regular grey sphere two hundred kilometres across. They were still very hard to see, swallowing or scattering electromagnetic radiation and offering nothing to Icebreaker’s other sensors. No hint of mass, or magnetism, or particle emission. Artificial, certainly, Kanu decided — and while the moons were larger than the worldwheels and the arrangement of their orbits an impressive feat, he found them less daunting an achievement than the surface structures. They were worthy of admiration, certainly, and definitely merited further attention — but he was content to relegate them to third place after the new Mandala and the worldwheels. They would suffice for study when the other wonders had been picked clean.

But as Icebreaker nosed its way through the dance of orbits, its sensors detected another dark thing circling Poseidon.

It was smaller than any of the moons, and consequently they had missed it until now. It was a light-second or two closer to Poseidon, orbiting more swiftly.

Kanu’s first thought was that they had chanced upon a piece of captured planetary debris — a tiny natural moon, blemishing the order of the forty-five artificial satellites. No solar system was free of primordial material, after all, and sooner or later some of those wandering fragments of early planet formation were bound to become gravitationally ensnared, tugged into orbits around larger worlds.

He was curious, though. Maybe there was water ice on this shard, tucked away in the shadows of craters. Maybe they could use it as a base for operations when they returned to take a closer look at Poseidon. He ordered Icebreaker to concentrate all its sensors on the little fragment and waited as the results appeared before him.

There it was: a sheared-off splinter of some larger thing — wider at one end than the other and hacked across at an angle with a very clean separation. Kanu stared at it wordlessly. He felt himself on the cusp of some vital recognition but not quite able to make the link.

It was Nissa who identified the thing.

‘That’s a Watchkeeper,’ she said, with a cool, calm reverence in her voice, as if she were speaking of the recently dead.

Which was perhaps the case.

It was the corpse of a Watchkeeper, not the living whole. They were looking at perhaps half of its former extent. It had been sliced in two, severed along an impossibly precise diagonal.

Kanu thought of the Watchkeeper they had seen on their way to Europa — the pine-cone form, the stabs of blue radiation spiking out from between the plates of its armour. They had always been dark apart from that blue light, but here there was only darkness.

‘Something killed it,’ he said.