Xeelee: Vengeance

by Stephen Baxter

  Poole shrugged.

  Now he found a feed about activities on the Moon. The lunar colonists were, by comparison, a handful, and for the Moon to be treated as a sideshow of Earth was, Poole knew, the satellite’s perpetual fate. That was so even now. But that second Probe was on its way nevertheless, carrying just as much lethal kinetic energy as the one destined for Earth.

  Poole discovered that the lunar Probe’s impact area had been narrowed down with similar precision to the calculations about the Earth-bound weapon: to the region of the Mare Serenitatis, in fact, where, as it happened, the Pooles had been constructing a massive accelerator, part of a new GUTengine manufacturing facility.

  Poole had spent a lot of time there, working with the lunar branch of mankind. Tall, spindly after generations of the lower gravity, their skulls big, their joints thick, they were stronger, wirier, faster-moving than they looked. And the miners and heavy engineers – who cracked the air they breathed out of the very rocks, and dug deep for iron and other minerals under the Moon’s thick mantle, and sculpted swathes of that forbidding surface to build vast engineering systems like the Poole accelerator, all in hard vacuum – were the toughest of all. Now Poole, fraught with guilt, sent messages of support to the staff and their families at Serenitatis, people working for the company part-owned by the man who had, it seemed, brought this calamity down on the Solar System. He signed off only when he was satisfied that a complete and timely evacuation had been arranged.

  Nicola watched over his shoulder. ‘That will knock a few per cent off the share price.’

  ‘Yeah, yeah. What’s next?’

  Next, at last, was action.

  Eighteen hours out from Earth, some of the ships from the ragged accompanying fleet started to move, taking up a new, loose formation around the Probe.

  Poole stood off and watched the formation gather, trying to guess the strategy. He’d heard no comms link chatter. As far as he could tell this operation hadn’t been authorised by any central body, any government arm. Not even the Federal Police – though the cop ships in the travelling cordon hung back, for now. Local decision-making.

  Then there was a flash, dazzling across several of the lifedome’s screens. A storm of light around the Probe. Through filters and using telescopic views, Poole could see projectiles bouncing off that hull plate carcass, and its milky surface shone with intense reflected radiation.

  A part of him exulted. Action, and obviously co-ordinated. Fifteen million kilometres out from Earth, and at last, for the first time since it had emerged from the Jupiter wormhole portal, the Xeelee’s works were under fire from human craft.

  ‘Well, that’s the kind of message to the alien I’m talking about,’ Nicola said, reading a scrolling analysis. ‘Looks like they’re using lethal-level projectile weapons, meant for the police as last-resort options. Surprised they’ve got hold of them. Also lasers, apparently comms weapons intensified to do some damage. They would slice open our lifedome like it was an eggshell.’

  ‘But they’re not doing the Probe any damage, are they?’

  ‘Not a scratch.’

  Poole rubbed his nose. ‘Highsmith Marsden might say that all this is bound to fail. That if the Xeelee hull plate is indeed some kind of condensed matter, then you’re not going to be able to harm it with conventional weapons. The way you can’t crack an atomic nucleus with chemical explosives. The orders of magnitude of the forces, the energies involved, are just too different.’

  ‘But you have to try.’

  ‘Yes—’

  Even more brilliant light blossomed on all their external-view softscreens, silent, wordless, dazzling even as transmitted through the screens.

  Nicola hurried to a monitor. ‘Phase two. I think that was a nuke. Thermonuclear explosion, a shaped charge – presumably meant for deep mining, on the Moon maybe. We’ve been hit by a pulse of hard radiation, heat energy.’

  ‘We’ll be safe enough in the Crab’s lifedome.’

  ‘I know,’ she said evenly. ‘Message incoming . . .’

  The monitors showed that in the vacuum of space the fireball from the nuclear detonation had dispersed almost immediately. And now Poole saw the smooth carcass of the Probe emerge from the glare, like some tremendous whale. Still laser light bathed the Probe; still projectiles spanged off that featureless surface. The alien seemed entirely unaffected.

  ‘Maybe the nuke weakened the hull plate, at least.’

  ‘Doubt it,’ Nicola said. ‘That thing went swimming in the Sun, remember, the biggest fusion engine in the Solar System. It probably just soaked up the energy and grew a bit.’

  ‘What about that message?’

  ‘It’s a warning, from one of the attacking ships. For us, and the rest of the congregation.’ She looked at him. ‘I was right about the nuke. It was sent by some bunch of lunar rock rats. Fighting harder than their terrestrial cousins, it seems.’

  Poole shrugged. ‘I know some of them. Not much appetite for ethical debates among those guys.’

  ‘Well, now they’re warning us all to stand off.’

  ‘Stand off? After they just set off a thermonuclear weapon? What else—’

  ‘I suggest you do as they say.’

  ‘Yes. Grab hold.’ A blip of thrust from the Crab’s drive pushed Poole back in his couch, and quickly put some distance between the GUTship and the Probe.

  Before another flower of light and energy blossomed.

  Nicola swore. If she was invoking more old gods, Poole had never heard of them. ‘That was matter-antimatter,’ she said. ‘Total conversion of mass to energy.’

  Poole frowned. ‘I wonder where they got that? Even Poole Industries uses antimatter sparingly, it’s so expensive.’

  She brought up more images. The hull plate whale swam on, utterly unperturbed. ‘They wasted their money. Or possibly yours.’

  Poole said, ‘I’m copying all this up to Highsmith Marsden, on Gallia. All the imagery, the sensor data – anything we have. I guess every failure tells us something about the nature of what we’re fighting.’

  ‘But we didn’t even deflect its course,’ she said bitterly. ‘Not by so much as a degree. I think the show’s over. The lunar guys are sticking around, and some of the police ships. But the rest are dispersing. You can’t blame them. They can’t follow this thing all the way down into Earth’s atmosphere . . . Lethe, I need a shower, I’ve been in this skinsuit too long. And I’m hungry. How does that make sense? I’ve just been a few kilometres from an antimatter bomb and I have a craving for synthesised breakfast bars.’

  ‘Shows you’re still human,’ Poole said.

  When she’d gone, he stayed at his station, glaring out at the Probe. Unwilling to take a break.

  Formulating a plan, of a sort.

  Wondering if he’d ever sleep again.

  38

  Six hours out from Earth. Less than twenty light-seconds, just a few million kilometres. Earth and Moon were clearly visible in Poole’s sky, the disc of Earth less than a degree across.

  Still the Hermit Crab trailed the Probe.

  The alien artefact was entirely unperturbed by all that humanity had thrown at it so far. Only a handful of ships remained of the monitoring fleet, most of them uncrewed observer drones. A couple of police ships had stayed around, but, Poole understood, only because the lunar miners who had attacked the Probe were technically under arrest.

  Messages from his father, among others, sat in the log, unread.

  Poole had asked Nicola to check out the flitter. He said they should prepare it for helping with disaster relief efforts to come on Earth: fix up the hold to take passengers, for instance. Somewhat to his surprise she’d bought the lie, and had gone out to the Crab Junior.

  So, right now, he was alone, in the lifedome. In his own ship, the Crab, positioned seventy kilometres from the Probe. Considering
the one option he had left.

  Time to act.

  Poole tapped a comms link. ‘Nicola? Where are you?’

  ‘Here, Michael. In the flitter. System checks done. I just—’

  ‘Good.’ He tapped a pre-programmed control, a single stroke that set in motion a string of operations.

  Nicola, predictably, detected the result immediately. ‘Hey. Hey! What have you done, Poole?’

  ‘Cast you adrift. Well, I say adrift – you’re safe, in a flitter that could take you back to Mars if you felt like it. I just shoved you out of the way.’

  ‘Out of the way? Of what?’

  ‘Of this. Turning the ship . . . Reverse thrusters . . .’

  In his control displays, and in his mind’s eye, Poole saw it: the kilometre-long baton that was the Hermit Crab, turning in space, the lifedome pointing towards the Xeelee Probe, the GUTdrive compartment and its huge chunk of asteroid ice swinging away like some tremendous drawn-back fist.

  Then the main GUTdrive opened up. An exhaust of superheated matter poured out at a velocity that was only one five-hundredth part below lightspeed itself. Poole was thrust back in his couch by a full gravity.

  And the Hermit Crab hurled itself, lifedome first, at the Xeelee Probe.

  Nicola called from the detached, left-behind flitter. ‘Poole, what in Lethe are you doing?’

  ‘What we maybe should have done from the beginning. I’ve given the Crab as much of a run-up as I could. The cops probably thought I was backing away.’

  ‘Collision in less than two minutes. You’ll kill yourself!’

  ‘That’s not the plan. Although, given all this is in some sense my fault, that would be fitting.’

  ‘Don’t talk like that.’

  ‘You know,’ he said through gritted teeth, pressed by the acceleration, ‘my first job, working for my father, was as a GUTship designer. I designed this ship, the Crab. But further back, at college on Earth, we were put through some pretty intensive ethical and political courses. Legacy of the Recovery era, my mother always says. A civilisation capable of building ships fast enough to reach the planets wields energies such that, if it ever waged war, you’re talking about suicide. Anyhow, ironically, during those courses about peace I realised that any GUTship is a potential lethal weapon. Time to put that theory to the test.’

  Lights lit up across Poole’s consoles and warning alarms chimed insistently as the ship itself became convinced of the reality of the upcoming collision. But as the seconds wound down, Poole’s override commands were holding.

  He pulled up his skinsuit hood, sealed it up, jammed on his helmet.

  Nicola said, ‘Looks as if we’re being hailed by every ship in this raggedy fleet of ours. Especially by the police. Orders to explain what we’re doing. Orders to stand down. A couple of more positive notes. “Give that Lethe-spawned thing one for me, Mike Poole.” That’s the lunar miners. Wouldn’t have thought they’d be so polite.’

  ‘Ignore them all. Whatever their orders, whoever has stayed with us this far wants to do this thing harm as much as we do. They’ll make a lot of noise, but they won’t stop me. Anyhow it’s too late, almost . . .’

  Everything about this operation was hasty, improvised. He’d only had a few hours, after all, to dream up the option, to simulate and game-play it a couple of times, to set it all up. And now, at this crucial moment, Poole wondered if it was just as well that he hadn’t had more time to think about it.

  ‘Your time’s nearly up. If you want a countdown—’

  ‘Do I sound as if I want a countdown? Just keep an eye on the automatics. If they do their job . . . around about . . .’ He braced against his couch. ‘Now—’

  Another jolt, a violent shove sideways, as secondary thrusters cut in.

  And the whole lifedome, as Poole had intended, sheared off from the spine of the GUTship, taking Poole, the sole passenger, with it. Poole felt the severance almost as a physical pain, almost as if his own head had been ripped from his body . . . Or maybe that was just anthropomorphism, his too-close identification with his ship, which he was now beheading.

  The separation in extremis of an intact lifedome was actually a safety feature which he’d designed in case of a sudden and disastrous failure of a GUTship’s main drive, a last-resort option to save the large populations of the big, heavily inhabited generation starships of the future. But it was pretty much experimental. The detachment mode had certainly never been tested on a full-scale ship, in high-speed flight.

  Now it had. Somewhat to his relief, it had worked.

  And as the lifedome, unpowered and helpless, spun away, his screens gave him a grandstand view.

  Of the decapitated remnant of the Crab driving itself like a spear into the hull of the Probe. Of the ship’s spine crumpling and cracking as it encountered the hull plate, lengthy sections wheeling out of the collision. Then, seconds later, the main GUTdrive pod itself, still wrapped in its huge block of asteroid ice, hurtled towards the Probe.

  Poole roared, ‘Probe this—’

  Just as Poole had set it, the engine overloaded on impact. A pulse of GUT energy, the energy that had once driven the expansion of the universe itself, was released right up against the hull plate surface of the Probe.

  Another astounding explosion, that must briefly illuminate all the worlds of the inner Solar System.

  The lifedome was hurled aside, like a grain of dust in a storm on Mars. Poole, shoved back in his couch by a force of many gravities, bared his teeth and yelled, wordless. The hull plate might be able to eat fusion heat and annihilating antimatter. Let it eat GUT energy . . .

  But – it did.

  His monitors showed the Probe sailing serenely out of another dispersing fireball.

  The light faded.

  Michael Poole breathed out.

  The lifedome seemed to have held, but Poole was unwilling to put that to the test by opening his suit. The whole dome was spinning uncomfortably rapidly, though.

  In his ear was a kind of slow clapping.

  ‘What in Lethe is that?’

  ‘It’s meant to be applause. Ironic applause, but applause. Well played, engineer.’

  ‘Did it work? Did I do any good?’

  ‘If you mean, did you deflect the Probe—’

  ‘I didn’t expect to destroy it, but I thought that the sheer momentum of the ship itself and the reaction-mass ice ought to be enough to turn it aside.’

  Silence.

  ‘No deflection?’

  ‘No deflection,’ Nicola replied.

  ‘Another data point for Highsmith.’

  ‘You know, Poole, you were a meek and mild engineer when I met you. A real stickler for the rules.’

  ‘Now look at me.’

  ‘Right. Well, I take the credit for the improvement. Seriously, Michael, it was worth a try. If it had worked—’

  ‘But it didn’t. And we don’t have anything left.’

  ‘That we don’t. And now—’

  ‘Earth’s in the way.’

  ‘I suppose you want picking up.’

  ‘The lifedome is spinning. The intercept might be tricky . . .’

  ‘I could handle it in my sleep. Shut up and admire.’

  After that, the final hours seemed to wear away quickly.

  Then, safe in the Crab Junior, Poole and Nicola watched as the Xeelee Probe struck Earth.

  39

  The Probe came down at approximately latitude thirty degrees north, twenty degrees west. This was in the eastern Atlantic, not far west of the Canary Islands. Poole saw it from space: a brilliant spark of light that must have been the hull plate-clad diamond block hitting the sea floor, flash-vaporising ocean-bottom muck and rock as easily as its sibling had scattered Martian dry-ice snow. And he supposed that, even as the consequences of that impact unfolded, the
Probe itself survived, embedded deep in the Earth, just as its sibling was now lodged somewhere inside the carcass of Mars.

  But it was those consequences that Poole witnessed next.

  A tremendous explosion. For a few moments Poole could see bare sea bed, as a great disc of ocean water was flashed to steam, exposing mud and rock smashed, melted and ruptured. Just as on Mars the layers of rock under the impact point had been compressed and then rebounded, catastrophically. A great pillar of glowing rock fragments and steam shot briefly into the sky, ejecta hurled up through the transient tube of vacuum cut through the air by the impactor.

  But this was not dry Mars. Already the wound in Earth’s grey sea was healing, cool ocean water closing over a well of tremendous heat. And then, as Poole watched, it was as if a great blister rose up on the surface of the sea, a shining silver dome.

  Nicola said quietly, ‘The energy pulse released was equivalent to a powerful earthquake. Or even a limited Anthropocene-era nuclear war.’

  ‘It feels like I’m watching a slowed-down recording.’

  ‘We’re seeing it from space,’ Nicola reminded him gently. ‘It’s hard to grasp the scale of things, from up here. If it looks slow, it’s not; it’s big, and very fast.’ She skim-read reports. ‘Seismometers across the planet are dancing . . . The impact may have set off some kind of undersea earthquake, or landslide. Which will in turn have added to the oceanic disturbances . . .’

  As Poole watched, that great blister of overheated water was already collapsing in on itself. Around a turbulent centre, over which a spiral of cloud was gathering – among other things, Poole realised, the infalling Probe had created an instant low-pressure weather system – a great ring wave was gathering, shining, flecked with white.

  Receding rapidly from the centre.

  Nicola tapped a couple of screens, calling up interpretations. ‘Wow. That is some wave. Coming out of the collapse of that initial dome of water. More than a kilometre high, moving at more than a thousand kilometres an hour.’