Xeelee: Vengeance

by Stephen Baxter

  From up here – or down here, under the south pole, Poole reflected, if you thought in terms of a position in relation to a conventional north-at-the-top display globe – planet Mars was a shield of dull orange. The south polar cap was a swirl of dirty cream, right at the centre of that shield: water ice layers millions of years old, cut into an intricate spiral pattern by persistent winds. The few human settlements this far south were mere blemishes on that great planetary hide, splashes of glassed-over green. Most of them were the migrant communities living off the ice at the fringe of the polar cap. Poole wondered if the migrants had managed one last season’s-end party at Hellas.

  And, directly ahead of Poole as he looked with Virtual eyes out of the flitter’s windows, there was the Xeelee. The alien itself was visible to him only with the ship’s deep probes, with neutrino pulses and other subtle instruments, for the Xeelee was still surrounded by a dense cloud of human craft, a cloud that shifted endlessly as ships were moved into fresh positions, or pulled out of the line for relief, refuelling, or rearming. Warships, that even now bathed the Xeelee continually with ferocious energies.

  Nicola fretted about the Xeelee’s location. ‘Why here, above a pole? And why this far out? It’s not even in orbit; it’s spending energy to station-keep every second it stays up here.’

  Poole grunted. ‘Somehow I don’t think station-keeping energy budgets are a great concern for a Xeelee—’

  A flash of light, cherry-red, in Poole’s peripheral vision.

  ‘Something’s changed,’ he said immediately.

  ‘Yes.’ They began to scan softscreens.

  It became obvious.

  From the heart of the rough sphere of human ships, beams of light now speared out, a gleaming, dazzling red – three of them coming from a common origin, arrowing dead straight through the cloud of ships. Beams scattering in three directions, separated by equal angles: beams that sheared off into the distance, to left, right, below from Poole’s point of view, staying coherent, brilliant, as far as Poole could track them.

  At first Poole assumed the beams must be aimed at the planet itself, but it soon became clear that their tracks passed over the surface of the planet before lancing on into space – but they terminated where the three beams each met one of the patient, waiting Xeelee drones.

  It was no surprise when the source of the beams was revealed as the Xeelee itself.

  The fleet of human ships kept its formation, but damage had been done as soon as the beams were fired up. Poole saw the hulk of a GUTship come drifting out of the crowd, spine sheared through, lifedome still pathetically bright. Poole had the intuition, though, that wrecking the ships of the escort fleet had nothing to do with the Xeelee’s true purpose here.

  Nicola was paging through softscreen displays, and Poole was aware of voices whispering in her ear. ‘We’re ordered to keep our positions, unless it’s to evade mortal danger, or help survivors of the wrecks. Those beams have created a lot of wrecks.’

  ‘What about the beams themselves?’

  ‘Nobody knows. Energy densities off the scale. They’ve spread out at lightspeed; they span thousands of kilometres. Nobody even knows how come they are visible at all. It’s not like a laser beam lighting up a cloud of dry ice. It seems they’re more like some kind of wound in spacetime itself.’ She looked up from her screens to peer through her window again, and Poole saw that terrible cherry-red light reflected in her face. ‘Lethe. Look at it.’

  Poole, trying to be analytical, was studying the geometry. ‘The three lines, those precise angles. It’s like looking down on some huge artefact. Like the Cache, when we visited it. Imagine hovering over one corner of that. You’d have the same impression, the convergent edges, thousand-kilometre lines meeting with the precision of a textbook diagram.’

  ‘Maybe it is something like that. A vast artefact, I mean . . . Look at this. There’s something new.’ Frowning, Nicola paged through a softscreen until she found a particular image, stroked the screen, Virtual-flung it into the air between them, where it rotated, three-dimensional. ‘This whole-planet view is a synthesis, a composite from many sensors, many angles – even observations from Earth . . .’

  The new image showed Mars, the whole of it, a globe the size of Poole’s fist, floating in the air, quite detailed: the polar caps, the red deserts, one hemisphere in shadow. Even a blur that was a dust storm over Utopia Planitia.

  But this was a Mars in a cage. A cage of light, connecting the Xeelee itself over the south pole to the three drones hanging over Mars’s northern hemisphere. And now, Poole saw, more beams of that dread cherry-red glow had condensed, connecting these three nodes in turn, in great triangular linkings. Completing the cage. Closing it.

  Nicola flicked the Virtual image with a fingertip; her gloved hand passed through the unreal projection, and it turned, slowly. That cage of light turned with it. ‘And so Mars is contained. It must be visible from the ground. Quite a sight.’

  Poole tried to focus on the cage itself. ‘The three drones,’ he said, studying detailed feeds. ‘Spread evenly around the low-latitude northern hemisphere: over Tharsis, over Arabia Terra, over Elysium, roughly. And, that geometry—’

  On impulse Nicola flipped the image over, so it was north pole down. Now Mars was like a marble sitting on the lower face of a tetrahedral box, a four-sided cage. The box couldn’t have been any smaller and still able to contain the planet, Poole saw; the other faces, if solid, would have brushed the planet’s surface. ‘A geometer would call that an insphere. The largest sphere the tetrahedron could contain without its surface breaking through the facets.’

  ‘A tetrahedron.’ Nicola grinned, but it was a strange, mixed expression, Poole thought: bitter, awed – defiant. ‘A tetrahedron the size of a planet. Seventeen thousand kilometres on a side. Earth’s diameter is only thirteen thousand kilometres. Even you Pooles never thought of building that big . . . And it’s precisely designed, too. I mean, to fit Mars, as closely as possible, just as you said. In fact, if those faces were solid, at their closest they really would come down to within a few kilometres of the planet’s surface.’

  ‘Why a tetrahedron?’

  Now she laughed. ‘Are you that dumb? Because of you, Poole. You and your tetrahedral wormhole mouths, and your tetrahedral amulet brought by some spooky alien babbling about the “Sigil of Free Humanity”. With this Lethe-spawned tetrahedral cage around Mars, the Xeelee is mocking you. Look what I can do. And you can’t stop it, can you?’

  Poole, awed by this apparently effortless planet-scale display of power – and fearing, deep in his gut, that she was somehow right about the connection of all this to his own personal destiny – tried to stay defiant. To keep thinking. But it was as if his own mind was in a cage as confining as the Xeelee tetrahedron.

  ‘Phobos,’ Nicola said now, distracted again.

  ‘What?’

  ‘Phobos has suddenly become a priority.’

  That threw Poole momentarily. ‘Phobos? Oh – of course. Deimos should be OK; that little moon orbits around twenty thousand kilometres above Mars’s surface. But Phobos is only six thousand kilometres up.’

  ‘And those vertices,’ Nicola said, ‘are seven thousand kilometres above the surface. So they’re evacuating Phobos, fast. If you’ve any stock in the Tangle shipyards, sell now—’

  Poole grabbed the Virtual globe-in-tetrahedron out of the air with his Virtual hand; his consistency protocols assigned it solidity and weight. ‘I’m going back down. Ask Grantt to meet me in the Grand Martian lobby. Good luck up here.’

  She seemed to reach out to him, just as his view of the flitter cabin dissolved in a hail of pixels.

  49

  As soon as his consciousness returned to his body in the Grand Martian sanatorium, Poole was able to push back the cover of his couch and stand unaided, despite the close attention of a couple of med-equipped bots that s
eemed oddly disappointed at a lack of ill effects or disorientation. He grabbed a skinsuit, donned it. He made sure that he still had access to Nicola’s Virtual, the Mars globe encased within its shell of cherry-red light; sure enough, it floated in the air at his shoulder.

  Then, without a word, he walked out of the sanatorium.

  The hotel lobby was a big, airy chamber, walled and roofed by glass, an elderly structure by Martian standards – and now almost like a scale model of the big arcologies that had been planned across the planet. And today it was crowded, with people sitting at tables or standing in clusters, looking out, talking in low tones. Some of them shimmered, blinked out of existence, reappeared; but most people seemed to be here in the flesh.

  Including Jack Grantt, who stood by a windowed wall, softscreen in one hand. Like Poole himself he wore a skinsuit, open at the neck, ready to be closed in an instant – a basic precaution that few others had taken, Poole noticed.

  As Poole approached, Grantt, evidently distracted, glanced at the Mars globe that hovered at Poole’s shoulder. ‘What in Lethe has been done to us?’ He flicked a finger at the big enclosing tetrahedron, which trembled briefly. ‘You want a drink? The bars are free of charge for the duration.’ He grinned wryly. ‘Always an upside, if you look for it.’

  ‘No. Thanks.’ Poole glanced around. ‘But there are plenty of takers.’

  Grantt shrugged. ‘It’s what people do, Michael. Ordinary people, not cerebral recluses like you and me. When a hard rain falls you want company, you listen to the news, you have a drink, you talk it over. That’s my theory anyhow. Which is maybe why you came back down yourself.’

  Poole shrugged. ‘Or maybe it’s just guilt.’

  ‘Guilt? Get that out of your head. Whatever’s to come, we need you thinking clearly.’ He peered up at the sky, uneasy. ‘You know, before the Hellas Probe hit, I sent my family to Phobos. Wife, kids and step-kids, grandchildren. Thought they’d be safe there, whatever happened down on Mars. Ha! Now I’m getting them off there fast.’

  ‘I’ll send a message to the Poole Industries people up there. If there’s anything they can do—’

  ‘I appreciate that.’

  Poole murmured the message.

  Then, moodily, he stepped to the window-wall.

  This hotel was at the edge of the city itself. Looking west, he gazed out at a butterscotch sky, and a raw landscape sparsely cluttered with roads and masts and various support facilities: still, essentially, Mars. But when he turned north he looked across a human landscape: Kahra itself, its domes and towers. The heart of the city was an island, almost like a miniature Manhattan, crowded with skyscrapers of a delicacy and height that would not have been possible under Earth’s heavier gravity. The most expensive single element, of course, was the deep, placid lake that surrounded that island: open water, the rarest of luxuries on Mars. This had to be pointed out to most visitors from Earth, where standing water was commonplace. This architecture, already centuries old, would have been dwarfed by the big dome at Cydonia, let alone the arcologies planned for Hellas and elsewhere, but still it was a monument to the ambition and style of a pioneering generation. Kahra had been a statement, a bit of Mars made like the Earth, a signal that humans were here to stay. But maybe that ambition meant nothing now.

  Because, as Poole looked up into the pale orange-brown of an afternoon sky, he could see a cherry-red stripe. Dead straight, beyond the atmosphere itself, only slightly obscured and discoloured by the thin, dust-laden air. The Xeelee had come here, and in minutes it had overwhelmed everything humans had done on Mars in millennia.

  ‘Look at that thing,’ Grantt muttered at his side. ‘There are some who are saying it actually casts a shadow, if you go outdoors. We’re keeping up the Virtual camouflage, by the way. The armies of Barsoom and the Mariner from Mars. Maybe that ornery settler type in Amazonis is taking pot-shots at the Xeelee right now with his gunpowder rifle. Whether or not that worked in luring in the Xeelee, it can’t make much difference now that—’

  A flash in the sky, there and gone. More crimson, in the corner of Poole’s eye.

  He looked around, baffled. Grantt had shut up. Other guests flinched back from the walls, gathered in groups, muttered in hushed tones. Only the bots, circulating with trays through the crowd, seemed unperturbed. Something had changed, again. Poole seemed to sense it from the reaction of the people around him, as much as by the event itself. Superhuman energies were being wielded on a superhuman scale, and maybe it was just too big to see, for an individual to take in. And yet people together, the mass, sensed the change. Still that cherry-red gash across the sky was visible, strong, static – that tetrahedral frame must be turning with the planet, he realised. His sense of unease deepened. What, then? What was new?

  Jack Grantt had pulled his skinsuit hood over his head; the suit was sealing itself up, a transparent visor dropping down before his face. ‘Listen. Let’s get out of here. Before they lock us up in our rooms with the other guests.’

  Which, Poole knew, was the protocol. On Mars you didn’t evacuate a hotel; the individual rooms were robust cells, virtually independent habitats in themselves, and people were safer there. A glance over his shoulder showed him that such a command was already being acted on; the drinks-serving bots had linked metallic arms in a kind of chain, and were herding guests back to their rooms.

  ‘Agreed.’ Poole pulled up his own hood and reached for his helmet. He and Grantt hurriedly walked out of the lobby, and to the airlock that led out of the city dome to the open terrain to the west.

  Poole, oddly, felt safer out in the Martian air. At least he knew the variables out here; at least he could anticipate the danger. Or he thought he could. Over his head, he saw that tremendous beam in the sky, an edge of the Xeelee tetrahedron, like, he thought, celestial scaffolding.

  Now Grantt pointed in the direction of the Tharsis volcanoes. ‘There.’

  Poole turned and looked that way. Far to the west, towards Tharsis, something new: another beam, cherry-red like the rest, that seemed to drop straight down from the sky to the ground. Almost like a space-elevator cable, he thought, to match the one at Olympus Mons. That must be what he’d glimpsed before, subliminally.

  All this in silence.

  Grantt said tightly, ‘This is what we glimpsed from the hotel.’

  ‘Yes—’

  ‘Are you there, Michael?’ Nicola’s sharp voice.

  Poole glanced at Grantt, and touched the biologist’s faceplate with one finger. ‘Copying Jack in.’

  ‘Get outdoors.’

  ‘Nicola, we’re ahead of you, we’re outside already. What’s happening?’

  ‘We’re under attack, is what’s happening,’ she said grimly. ‘About three minutes ago, each of the four vertices of the Xeelee tetrahedron let loose a beam – the Navy types up here are calling it a planetbuster. Same energy intensity as the beams that connected the tetrahedron in the first place. But now these four are blasting straight down at the ground, from each corner. You should be able to see the nearest, coming down on Tharsis, to your west . . .’

  ‘We have it, Nicola.’ Now, looking to the west, Poole saw a kind of glowing pillar following that line of cherry-red light back up towards the sky. And darkness spreading, very high.

  ‘If you want the global picture take a look at your Virtual . . . downloading updates.’

  The Virtual display Poole had brought down from orbit hovered patiently, an arm’s length from his head. There was Mars, that fist-sized globe, one hemisphere still illuminated by an invisible sun, the other in shadow. There was that spiky tetrahedral cage of rich red light around the planet, looking oddly inverted, with its apex under the planet’s south pole. But now new beams of light and energy, new cherry-red girders, had been added to the structure. They descended from each of the four vertices, apparently aimed straight towards the centre of the planet. Firing st
raight down at the surface, he saw, at the ground, and into it.

  ‘As an abstraction,’ Jack Grantt said, ‘that looks almost beautiful. As if the Xeelee have made a pendant of Mars, put it in a setting like a precious stone . . .’

  ‘So,’ Nicola said, ‘one target site is the south pole, under the Xeelee. The others are spread around the northern hemisphere, under the drones. One in Tharsis – about a thousand kilometres from Kahra, I think. One in Arabia Terra. One in Elysium.’

  Poole saw that the central image of Mars was already changing. Even as he watched, where the four descending beams struck, a kind of dark blight was spreading across the planet’s surface. And whole regions of Mars seemed to flicker and grow darker, plainer. The Virtual dioramas collapsing as the power failed, Poole supposed.

  ‘Nicola, can I see a touchdown point?’

  ‘Just magnify the image.’

  Poole dug his hands into the turning planet, feeling nothing, expanding the image easily. He manipulated it until he had extracted a god’s eye view of the Tharsis region, the great volcanoes like huge, shallow blisters.

  The beam had grounded not far from the flank of Olympus itself, a cherry-red thread from the sky. Where it touched he saw a central bright spark, what looked like a walled crater around it, a wider area of smashed and broken ground. All this presumably caused in the first instants of the touchdown, an injection of energy, as if another huge mass, a greater Probe, had hit the planet.

  But this wasn’t a simple impact; the energy had continued to stream down from the sky. So there was a kind of continuing explosion going on in that central region, and more waves of smashed, semi-molten rock washed out, overwhelming mountainous crater walls themselves only a few minutes old. The ground around the strike was actually liquefying, Poole saw, staying molten, a lake of magma growing wide and deep and ever hotter.