Redemption Ark

by Alastair Reynolds

  Which was true, Skade knew, but there would be little practical advantage in accelerating harder. Relativity ensured that. Arbitrarily high acceleration would compress the subjective duration of their journey to Resurgam, but it would make almost no difference to the objective time that the journey consumed. And it was that objective time which was the only relevant factor in the wider picture: it would still take the same amount of time to reach Resurgam as measured by external observers, and more decades still to rendezvous with the other elements of the exodus fleet.

  Still, there were other reasons to consider an increase in acceleration. And at the back of Skade’s mind was a dangerous and alluring possibility that would change the rules entirely.

  ‘And the other ship?’ Felka asked. ‘Where is that?’

  Skade had already told her about the vessel behind them. Now a second circle bisected by two cross hairs appeared on the display almost exactly centred above the one that demarked Epsilon Eridani.

  That’s it. It’s very faint, but there’s a clear tau-neutrino source there, and it’s moving on the same course as us.

  ‘But a long way behind,’ Felka said.

  Yes. Three or four weeks behind us, easily.

  ‘It could be a commercial ship, Ultras or something, on a similar heading.’

  Skade nodded. I’ve considered that possibility, but I don’t find it likely. Resurgam isn’t a very popular destination for Ultras, and if that ship were headed for another colony in the same part of the sky, we’d have seen lateral motion by now. We haven’t — she’s dead on our tail, Felka.

  ‘A stern chase.’

  Yes, deliberately following us. They have a modest tactical advantage, you see. Our flame points towards them; theirs points away from us. I can track them because we have military-grade neutrino detectors, but it is still difficult. But they need no finesse to spot us. I have separated our thrust beams into four components and given them a small angular offset, but they need only detect a tiny amount of leaked radiation to fix our position. We are neutrino-quiet, however, and that will give us a definitive advantage after turnover, when we have to point our flame towards Resurgam. But it won’t come to that. That ship can’t ever catch us, no matter how hard it tries.

  The ship should be falling behind already,‘ Felka said. ’Is it?‘

  No. So far she has maintained two gees all the way out from the Rust Belt.

  I didn’t think normal ships could accelerate that hard.‘

  They can’t, not usually. But there are methods, Felka. Do you know the story of Irravel Veda?

  ‘Of course,’ Felka said.

  When she was pursuing Run Seven she modified her own ship to manage two gees. But she did it the crude way — not by improving the efficacy of her Conjoiner drives, but by stripping her ship down to a skeleton. She left all her passengers behind on a comet to save mass.

  ‘And you think that other ship must be doing something similar?’

  There’s no other explanation. But it won’t help them. Even at two gees they cannot close the gap between us, and the gap will widen if we increase our inertia-suppression effect. They cannot match three gees, Felka; there is only so much mass you can strip out of a ship before you haven’t got a ship at all. They must be very near the limit already.

  ‘It must be Clavain,’ she said.

  You seem very certain.

  ‘I never thought he’d give up, Skade. It just isn’t his style. He wants those weapons very badly, and he isn’t going to let you get your cold steel hands on them without a fight.’

  Skade wanted to shrug, but her armour would not allow it. Then it confirms what I have always suspected, Felka. Clavain is not a rationalist. He is a man fond of gestures, no matter how futile or stupid they might be. This is merely his grandest and most hopeless gesture to date.

  Clavain ran into the first of Skade’s traps eight hundred AU from Yellowstone, one hundred light-hours into the crossing. Clavain had been expecting her to try something; he would, in fact, have been disappointed and a little alarmed had she not. But Skade had not let him down.

  Nightshade had sown mines behind it. Over a period of weeks, Skade had dropped them from her ship’s stern: small, automated, highly autonomous drones stealthed for maximum invisibility against Clavain’s forward-looking sensors. The drones were small enough that Skade could afford to manufacture and deploy them by the hundreds, littering Clavain’s forward path with hidden obstacles.

  The drones did not have to be very clever or have great range. Skade could be quite certain of the trajectory that Clavain would be obliged to follow, just as he could be quite certain of hers. Even a small deviation away from the direct line between Epsilon Eridani and Delta Pavonis would cost Clavain precious weeks, further delaying his arrival. He was already lagging behind, and would not wish to incur any further hold-ups if he could help it. So Skade would have known that Clavain would remain on the same heading except for short-term deviations.

  That still meant she had a lot of space to cover. Explosions were not an efficient means of inflicting harm on space vessels at anything other than extreme close range, since vacuum did not propagate shock waves. Skade would know that the odds of one of her mines coming within a thousand kilometres of Clavain’s ship were so small as to be negligible, so there would be no point putting crustbuster-class warheads in them. Clavain expected, instead, that the mines would be designed to identify and fire at his ship across a typical range of light-seconds. They would be single-use launchers, particle beams, very probably. It was exactly what he would have done if he were being chased by a similar ship.

  But Skade had used crustbusters. She had inserted them, so far as Clavain could judge, into every twentieth mine, with a statistical bias towards the edge of her swarm. The warheads were primed to detonate as soon as he came within one light-hour of them, as near as he could tell. There would be a distant prick of hard blue light, shading into violet, red-shifted from Clavain’s rest frame by a few hundred kilometres per second. And then, hours or tens of hours later, another would detonate, sometimes two or three in close succession, stammering out of the night like a cascade of fireworks. Some were closer than others, but they were all much too distant to do any harm to Clavain’s ship. Clavain ran a regression analysis on the spread pattern and concluded that Skade’s bombs had only a one in one thousand chance of damaging his ship. The chances of a destructive strike were a factor of one hundred less favourable. Clearly, they were not meant for that purpose.

  Skade, he realised, was using the crustbusters purely to increase the targeting accuracy of her other weapons, flooding Clavain’s ship with strobelike flashes which nailed its instantaneous position and velocity. Her other mines would be sniffing space for the backscatter of reflected photons from his own hull. It was a way of compensating for the fact that Skade’s mines were too small to carry neutrino detectors, and were therefore reliant on outdated positional estimates transmitted back from Nightshade, many light-hours further into interstellar space. The crustbusters smoked Clavain’s ship out of darkness, allowing Skade’s directed-energy weapons to latch on to it. Clavain did not see the beams of those weapons, only the flash of their triggering explosions. The yields were about one hundredth of a crustbuster burst, which was sufficient to power a particle beam or graser with a five-light-second extreme kill range. If the beam missed him, he never saw it at all. In interstellar space there were so few ambient dust grains that even a beam passing within kilometres of Clavain’s ship would suffer insufficient scattering to reveal itself. Clavain was a blind and deaf man stumbling across no man’s land, oblivious to the bullets zipping past him, not even feeling the wind of their passage.

  The irony was, he probably wouldn’t even know it if a beam hit.

  Clavain evolved a strategy that he hoped might work. If Skade’s weapons were firing across typical distances of five light-seconds, they were dependent on positional estimates that were at least ten seconds out of date, and prob
ably more like thirty seconds. The targeting algorithms would be extrapolating his course, bracketing his likely future position with a spread of less likely estimates. But thirty seconds gave Clavain enough of an edge to make that strategy enormously inefficient for Skade. In thirty seconds, under a steady two gees of thrust, a ship changed its relative position by nine kilometres, more than twice its hull length. Yet if Clavain stuttered the thrust randomly, Skade would not know for sure where in that nine-kilometre box to direct her weapons. She would have to assign more resources to obtain the same probability of a kill. It was a numbers game, not a guaranteed method of avoiding being killed, but Clavain had been a soldier long enough to know that this was, ultimately, what most combat situations boiled down to.

  It appeared to work. A week passed, and then another, and then the smaller bursts of the particle beams ceased. There remained only the occasional, much more distant flash of a crustbuster. She was keeping her eye on him, but for now she had abandoned the idea of taking him out with anything as simple as a particle beam.

  Clavain remained watchful and nervous. He knew Skade.

  She wouldn’t give up that easily.

  He was right. Two months later a fifth of the army were dead, with many more injured and likely to die in the weeks ahead. The first hint of trouble had been innocuous indeed: a tiny change in the pattern of light that they were detecting from Nightshade. It seemed impossible that such a trifling change could have any impact on their own ship, but Clavain knew that Skade would do nothing without excellent reason. So once the change had been verified and shown to be deliberate, he assembled his senior crew on the bridge of the stolen lighthugger.

  The ship — Scorpio had named her Zodiacal Light, for obscure reasons of his own — was a typical trade lighthugger, manufactured more than two hundred years earlier. The ship had been through several cycles of repair and redesign in the intervening time, but the core of the vessel remained mostly unchanged. At four kilometres long the lighthugger was much larger than Nightshade, her hull voided by cavernous cargo bays large enough to swallow a flotilla of medium-sized spacecraft. The hull itself was approximately conic, tapering to a needle-sharp prow in the direction of flight, with a blunter tail to stern. Two interstellar drives were attached to the hull via flanged spars flung out from the cone’s widest point. The drives were barnacled with two centuries’ worth of later accretions, but the basic shape of Conjoiner technology was evident beneath the growth layers. The rest of the hull had the dark smoothness of wet marble, except for the prow, which was cased in a matrix of ablative ice sewn through with hyperdiamond filaments. As H had said, the ship itself was essentially sound; it was the former crew’s business methods that had made them insolvent. The army of pigs, trained not to harm anything irreplaceable, had succeeded in minimising damage during the capture itself.

  The bridge was a third of the way back from the prow, one point three five kilometres of vertical distance when the ship was accelerating. Most of the technology in it — indeed, most of the technology aboard the ship — was ancient, both in feel and function. Nothing about that surprised Clavain: Ultras were notoriously conservative, and it was precisely because they hadn’t adopted nano-technologies to any great degree that they continued to play a role in these post-plague days. There were general-purpose manufactories in the belly of the ship, now running full-time on weapons production, with no capacity to be spared to upgrade the fabric and infrastructure of Zodiacal Light. It had not taken Clavain very long to settle into the museumlike ambience of the huge old ship; he knew such robustness would serve them well in any battle against Triumvir Volyova.

  The bridge itself was a spherical chamber within a gimballed arrangement that permitted it to swivel according to whether the ship was under thrust or rotating. The walls were quilted with projection systems, showing exterior views of the ship captured by drones, tactical representations of the immediate volume of space and simulations of various approach strategies for the arrival in the Resurgam system. Other parts of the walls were filled with scrolling text in old-fashioned Norte script, a steady litany of shipboard faults and the automatic systems that were triggered to fix them.

  A railinged, circular dais made of grilled red metal held seats, display and control systems. The dais could accommodate about twenty people before it became uncomfortable; Clavain judged that it was somewhere near its maximum capacity right now. Scorpio was there, of course, with Lasher, Shadow, Blood and Cruz: three of his pig deputies and a one-eyed human woman from the same criminal underworld. Antoinette Bax and Xavier Liu, filthy from hastily abandoned repairwork, sat near the back, and the rest of the dais was taken up by a broad mixture of pigs and baseline humans, many of who had come directly from the Chateau’s employment. They were experts in the technology H had pieced together and, like Scorpio and his associates, had been convinced that they were better off joining Clavain’s expedition than staying behind in Chasm City or the Rust Belt. Even Pauline Sukhoi was there, ready to return to the work that had wrenched askew her personal reality. To Clavain she looked like a woman who had just stumbled out of a haunted house.

  There’s been a development,‘ Clavain said when he had their attention. ’I don’t quite know what to make of it.‘

  A cylindrical display tank, an antique imaging system, sat in the middle of the dais. The interior of the tank contained a single transparent blade of helical profile that could be rotated at great speed. Coloured lasers buried in the base of the tank pulsed beams of light upwards, where they were intercepted by the moving surface of the blade.

  A perfectly flat square of light appeared in the tank, rotating slowly to bring itself into view of all those on the bridge. This is a two-dimensional image of the sky ahead of us,‘ Clavain said. ’Already there are strong relativistic effects: the stars shifted out of their usual positions, and their spectra shifted into the blue. Hot stars appear dimmer, since they were already emitting most of their flux in the UV. Dwarf stars pop out of nowhere, since we’re suddenly seeing IR flux that used to be invisible. But it isn’t the stars I’m interested in today.‘ He pointed to the middle of the square, to one dim, starlike object. This thing here, which looks like a star as well, is the exhaust signature from Skade’s lighthugger. She’s done her best to make her drive invisible, but we’re still seeing enough stray photons from Nightshade to maintain a fix.’

  ‘Can you estimate her thrust output?’ Sukhoi asked.

  Clavain nodded. ‘Yes. The temperature of her flame says she’s running her drive at nominal thrust — that would give her a gee of acceleration, for a typical million-tonne ship. Nightshade’s engines are smaller, but she’s also a small ship by lighthugger standards. It shouldn’t make that much difference, yet she’s managing two gees, and she’s occasionally pushed it to three. Like us, she has inertia-suppressing machinery. But I know she can push it much harder than this.’

  ‘We can’t,’ Sukhoi said, turning paler than ever. ‘Quantum reality is a nest of snakes, Clavain, and we are already poking it with a very sharp stick.’

  Clavain smiled patiently. ‘Point taken, Pauline. But whatever Skade manages, we must find a way to do as well. That isn’t what’s troubling me, though. It’s this.’ The wheeling images changed almost imperceptibly. Skade’s signature became slightly brighter.

  ‘She’s thrusting harder, or she’s changed her beam geometry,’ Antoinette said.

  ‘No, that’s what I thought, but the additional light is different. It’s coherent, peaked sharply in the optical in Skade’s rest frame.’

  ‘Laser light?’ Lasher asked.

  Clavain looked at the pig, Scorpio’s most trusted ally. ‘So it would seem. High-power optical lasers, probably a battery of them, shining back along her line of flight. We’re probably not seeing all the flux, either, just a fraction of it.’

  ‘What good will that do her?’ Lasher said. He had a black scar on his face, slashed like a pencil line from brow to cheek. ‘She’s much too far ah
ead of us for that to make any sense as a weapon.’

  ‘I know,’ Clavain said. ‘And that’s what worries me. Because Skade won’t do anything unless there’s a good reason for it.’

  ‘This is an attempt to kill us?’ the pig asked.

  ‘We just have to figure out how she hopes to succeed,’ Clavain replied. ‘And then hope to hell that we can do something about it.’

  Nobody said anything. They stared at the slowly wheeling square of light, with the malign little star of Nightshade burning at its heart.

  The government spokesman was a small, neat man with fastidiously well-maintained fingernails. He despised dirt or contamination of any sort, and when the prepared statement was handed to him — a folded piece of synthetic grey government vellum — he took it between his thumb and forefinger only, achieving the minimum possible contact between skin and paper. Only when he was seated at his desk in Broadcasting House, one of the squat buildings adjoining Inquisition House, did he contemplate opening the statement, and then only when he had satisfied himself that there were no crumbs or grease spots on the table itself. He placed the paper on the desk, geometrically aligned with the table’s edges, and then levered it open along its fold, slowly and evenly, in the manner of someone opening a box that might possibly contain a bomb. He employed his sleeve to encourage the paper to lie flat on the surface, stroking it across the text diagonally. Only when this process was complete did he lower his eyes and begin scanning the text for meaning, and then only so that he would be certain of making no mistakes when delivering it.

  On the other side of the desk, the operator aimed the camera at him. The camera was a cantilevered boom with an old float-cam attached to the end of it. The float-cam’s optical system still worked perfectly, but its levitation motors were long expired. Like many things in Cuvier, it was a taunting reminder of how much better things had been in the past. But the spokesman put such thoughts from his mind. It was not his duty to reflect on the present standard of living, and — if truth be told — he lived a comfortable enough existence by comparison with the majority. He had a surplus of food rations and he and his wife lived in a larger than average domicile in one of the better quarters of Cuvier.