Xeelee: Vengeance

by Stephen Baxter

  And now the raindrop began to do something the Ghost had not done.

  The perfect sphere was perfect no more. Lines appeared on its surface, running from pole to pole as Poole looked at it, lines of longitude scratched onto a silver-gilt globe. Those lines widened, thickened – darkened, and each flashed briefly with cherry-red light. Then the spherical shell split open, along the bright lines, and its segments peeled away. The angel was opening its wings, Poole thought.

  To reveal a cluster of diamonds.

  Diamonds, yes: the thing exposed was made of a glassy material that glimmered in the pale light shining from the hull plate. Like its abandoned container, it was a rough sphere in overall form, but it was open, a network of struts and planes, studded with jewels that gleamed. And it spun, slowly.

  As the flitter hung in the air, more of these objects joined this first visitor, shedding their silver carcasses as they went, until they were suspended all around, like chandeliers hanging from some invisible ceiling.

  Grantt was staring. ‘By Ares’ balls! Apologies, an old Martian expression . . .’

  ‘You’re forgiven. They look alive . . . Sorry – you’re the biologist.’

  Grantt was smiling. ‘Yes. But your intuition is good, Michael.’ He seemed to have to force himself to turn away, to look down at his data screens, to tap instructions for fresh analyses. ‘Our visitor out there is exactly what it looks like, a structure of carbon – of diamond, essentially, that’s the basic substance, though I can see other forms in there: graphite, carbides, even some kind of monomolecular filament. And alive? It has a lot of the characteristics of life, at first glance. That structure is orderly, but it’s fractal – lots of similar patterns on a variety of scales, from the molecular on up. It looks as if it has grown.’

  Poole had spotted another crowd of these ‘creatures’, out of his left-hand window. The newcomers looked like smaller copies of the big beasts in the main window, maybe a dozen of them, swarming around each other, rolling, glittering, shining, moving so quickly they were hard even to count.

  He pointed. ‘And they look as if they are still growing.’

  Grantt laughed out loud. ‘They do look young, don’t they? Immature. Not just because they are smaller. They’re playful! And they seem more interested in each other than in us. That’s kids for you. Believe me, I have children and grandchildren, I should know.’

  ‘Life made of diamond, then.’

  ‘More importantly, carbon. Michael, you are a creature of carbon compounds. It’s just that the carbon molecules lying around on Earth when it came time to evolve your ancestors were obviously rather different than in the environment these fellows evidently came from.’

  ‘Raindrops.’

  ‘Hmm?’

  ‘That’s the nickname we gave these creatures when the first of them came through the Jupiter wormhole. Because of those silver carapaces; they looked like raindrops when you saw a crowd of them. That name doesn’t seem appropriate any more.’

  ‘No. Quite right.’ Grantt searched for more data. ‘Those outer carapaces, as you put it, appear designed to be discarded. As we put on pressure suits. This is their true form. Not only that, as you know, the carapaces are made of the light-growth stuff we’ve been calling membrane, which is something different. Not molecular carbon at all. Like the hull plate, it’s more like some kind of condensed matter.’

  ‘Manufactured, then? As we manufacture pressure suits?’

  ‘Maybe. Maybe not. The condensed-matter tech doesn’t fit with the rest . . .’ More softscreen-tapping. ‘We’ve got whole panels of observers following our every move, via Nicola’s relay. I get the sense you don’t like the scrutiny, but for me it’s useful, an ongoing brainstorm by some of the smartest people in the Solar System – although some of them, such as on Earth, are too far away to respond quickly, thanks to lightspeed delay. Anyhow they roughly back up our conclusions – these entities seem more usefully described as living, than not.’ Grantt grinned. ‘This is science in action, Michael. Hypothesising on the fly. But for sure, the name you gave them is wrong.’

  ‘Paragons,’ Nicola called.

  ‘What’s that?’

  ‘I’m listening in too. A consensus is emerging about a better name. “Paragons.” The word can be a synonym for “diamonds”. And those beautiful pictures you’re sending – your father says he’s already had queries about image rights.’

  Poole had to laugh. ‘That’s Harry.’

  ‘Well, maybe you Pooles deserve it,’ Grantt said. ‘You got us here, after all. Someday we’ll dream up a biological nomenclature for these creatures, and whatever ecology they come from. But for now, Paragons it is.’

  Nicola said evenly, ‘We don’t exactly have a timetable here. There’s no sign yet of that lesion you entered through healing up, or its partners in the other faces. But . . .’

  ‘Time may be short,’ Grantt said. ‘And we need to be data-gathering. Theorising comes later.’ He glared out of the forward window, at the nearest, slowly turning Paragon, which continued to inspect them back. ‘A rough axial symmetry. Which probably implies an origin in a strong-gravity environment, and an evolution for buoyancy – did they evolve in some kind of ocean?’

  Poole said, ‘You know, Jack, for a pioneering exobiologist you can be remarkably unobservant. About the big picture anyhow. You’re looking for an ocean? How about this one?’

  He tipped the flitter up on its nose. That didn’t trouble Poole – the gravity in here was negligible anyhow. But Grantt gulped and grabbed hold of his harness.

  And there before them, just as Poole had glimpsed before, was the Cache’s inner world.

  A rough sphere, like a captive asteroid, dominating the inner space. A hasty check of Grantt’s data showed that it was six hundred kilometres in diameter, compared to the Cache’s thousand. Yes, about the size of a big asteroid, like Vesta.

  But this was a miniature world, of land and oceans, lakes that shone like mirrors as they reflected the soft light of the distant, planet-sized walls. On the land Poole thought he saw uplifted plains, even chains of stubby mountains cut through by winding river valleys. The object was Earthlike in some ways, then, but not in others; aside from the whole being so small, these landscapes were wrought in dark colours, sombre crimsons and greys and blacks.

  But like Earth it was clearly inhabited. Clusters of lights shone on those dark plains, and along the river valleys. There were even what looked like roads, threads through the compact geography along which some of those gleaming shards seemed to travel.

  ‘Like Earth,’ Poole murmured. ‘But – not.’

  ‘More puzzles! There’s a pretty dense layer of air wrapped around that miniature world. I say air – the same stuff as we’re swimming in, the mix of carbon monoxide and methane and other carbon compounds. But the pressure is a lot higher – more than a bar actually, more than Earth’s atmosphere.’

  Poole nodded. ‘OK. So what keeps that layer of air sticking to the planetoid?’

  ‘Not gravity.’ Grantt consulted his data streams. ‘At a guess, the same kind of barrier that’s sealing up the lesions in the box itself. Something that’s permeable to massive objects, impermeable to gases: a smart force field. And it wraps up the whole world. Maybe this is an emulation of the environment of a much larger world. Like our own arcologies, boxes with Earthlike conditions inside.’ He grinned. ‘My friends in Hellas would love this. An arcology the size of Vesta. The data’s pouring in . . . Our first interpretations can only be impressionistic. Those gleaming light clumps are Paragons, I think, grouped together, maybe even joined physically somehow – they look as if they could interconnect, interlock. Maybe they can form composite organisms. Even group minds.’

  Nicola murmured, ‘Are our imaginations running away with us, gentlemen?’

  ‘Sorry. But, meanwhile, the heat profile is remarkable. The su
rface is at the same temperature as the bath of gas within which this little world swims. You know, this environment reminds me of something. Planets floating in a warm sky. I’m sure there’s an analogue in cosmological theory, papers I’ve seen somewhere . . .’

  ‘Those Paragons,’ Poole said, peering ahead. ‘There’s a group. Down on the planet, directly ahead of us. Look like they’re working on something. Something big.’

  Grantt smiled. ‘Ahead of us. I keep forgetting we’re dangling nose-down over this thing, like some huge ornament.’

  ‘Nicola, it’s hard to see through this murky air. What are they doing down there? Digging a pit, maybe. Like a mine shaft?’

  ‘A deep one,’ Nicola said. ‘That’s what your radar echoes show. Yes, some kind of shaft; can’t tell how deep. And it’s a hundred metres across, give or take. Which is suspiciously similar in size to the big hole in the Cache you’re sitting right underneath.’

  A faint alarm sounded in Poole’s head as he visualised that: a huge shaft underneath a breach in the hull. ‘You have an interpretation?’

  ‘Not yet. We’re working on it. Me and a Solar System full of avid geniuses. Many of them have fixed on the detail about the carbon, Jack. Carbon-based life forms, OK. And you said the air around you is dominated by carbon products—’

  ‘That’s it,’ Grantt said eagerly. ‘I think. Carbon! The references I was trying to remember. And even the planetoid in front of us – I have a deep-scan report here somewhere . . .’ He stroked a screen with one finger, scrolling through pages. ‘Here it is. Michael, what would you guess that worldlet itself is made of?’

  Poole shrugged. ‘I’d guess the same stuff every small object in the Solar System is made of, from Vesta up to the Earth. A mix of water ice and rock.’

  ‘By rock you mean silicate minerals? Well, you’re wrong. According to this deep scan. That’s a world, hosting carbon-based life, that is itself made of carbon – of graphite, carbides, what’s presumably a diamond core. Very little in the way of silicate compounds, because there’s very little silicon present. And even less iron, and other heavy elements. Those shallow seas are water, though, but so heavily carbonated they probably fizz . . .’

  Poole shook his head. ‘I’m no planetologist. Where would you find a world made of carbon?’

  Grantt shook his head. ‘Wrong question. I’m finally putting all this together, I think. Kind of slowly, but it is a novel situation.

  ‘Michael, the question isn’t so much where you’d find a carbon planet, but when.’

  32

  Jack Grantt spoke of the deep past of the universe.

  Of ages still warmed by the afterglow of the Big Bang itself, the titanic spacetime explosion that had begun the cosmic story.

  ‘It’s ten million years after the singularity. Fifteen, maybe. The universe is expanding at lightspeed, but it’s still small, and dense, all that mass and energy jammed in tight. There’s light, lots and lots of radiant energy. And there are already stars, big bloated beasts that run through their lifecycles in a couple of million years, and then detonate, spewing their fusion products into a universe that is otherwise still composed of pretty much nothing but the hydrogen and helium that had come out of the Big Bang.’

  ‘Those fusion products,’ Nicola said. ‘Aside from helium—’

  ‘Mostly carbon, oxygen, nitrogen. Only traces of heavier elements so far, through to iron. It was the later generations of stars, that formed from the debris of the primordial giants, that pushed the fusion processes further, and produced silicon and iron in bulk. But in those early times there would have been masses of carbon, busily combining with oxygen and hydrogen to form molecules.’

  ‘Carbon monoxide and methane,’ Poole said.

  ‘Yes. And you’d have carbon grains, even bits of diamond, coming together to make dust and rocks and planetesimals and—’

  ‘Planets,’ Nicola said.

  ‘Correct. Carbon worlds – of which this is a shrunk-down scale model. Very rapidly formed. Water on the surface maybe, but only traces of iron in the interior – certainly no big hot iron cores, like Earth.

  ‘You had more stars being formed, of course – but these odd worlds were kept warm from the beginning, even away from the stars. Warmed by the glow of the sky. By the afterglow of the Big Bang itself. Once, remember, the universe had been so hot that the very structure of spacetime had been broken down. Already it was cooling, on its way to the chilly three-degrees-absolute temperature we see today. But then, a mere ten million years in, in between those two extremes, you had a sky that was still glowing with a comfortable heat: warm enough in itself to keep water liquid on a planet’s surface.

  ‘Today, in the Solar System, what we call the habitable zone is pretty much where Earth is: not so close to the Sun that the oceans boil away, not so far out that they freeze. Back then, the whole universe was a habitable zone, where you could potentially find liquid water on any planet, no matter how far from a star. The cosmos was probably never so welcoming to life again. So, carbon-rich worlds, crawling with carbon-based life, evolving fast in all that rich warm chemistry. Just as we see here. Incredible. But what are they doing here? Or, in fact – why are they here now . . .?’

  ‘Michael.’

  ‘I’m here, Nicola.’

  ‘Reading something new.’

  Poole felt his heart beat a little faster, a surge of adrenaline. Working around the Io flux tube you acquired certain instincts: any change was something to be wary of. ‘Tell me.’

  ‘That mine shaft before you.’

  ‘Looking down its throat right now.’

  ‘And the others. There’s a build-up of energy . . . A lot of energy.’

  Poole pictured it again. The great barrel before him. A hole in the Cache shell right behind him. His small, fragile ship in the way. And now, on the surface of the worldlet itself, right in front of him, he saw a flow of light sparks fleeing from the hole in the ground, clusters or multiples of the Paragons.

  He kept his hand on the thruster control.

  ‘This is why we’ve been able to get in here,’ he said softly. ‘Why those holes in the hull opened up. Nicola. That’s not a mine shaft at all, is it?’

  Light and smoke spewed from the pit in the ground.

  ‘It’s a cannon,’ Nicola said softly.

  Poole watched, amazed, as billowing smoke gushed out of the cannon mouth and into the air, rising until it was trapped under the Cache roof, soon turning the whole world into a kind of smoke globe.

  Meanwhile, down in the pit, that central light was growing brighter. In that vast muzzle. And the flitter was still in the line of fire.

  Poole yelled, ‘Hang on!’ He yanked at the thruster control. His body seemed to work independently of his conscious mind, his reflexes taking over. Lateral thrusters kicked in, throwing the flitter sideways, ignoring any obstacles in the crowded air, a motion savage and uneven.

  Taken by surprise, Grantt was jolted hard, and he grunted, hanging on to his harness.

  And a gleaming mass, glowing white-hot, smashed its way out of the muzzle. The projectile screamed past the flitter, just, and flew straight out through the hole in the Cache hull.

  In the thin air there was enough of a wake to make the flitter buck and twist, and Poole wrestled for control.

  Later Poole would learn that the projectile was one of three, shot out of the three apertures in the Cache, from three identical cannons. Each projectile appeared to be a mass of diamond, a rough sphere some forty metres across, massing about a hundred thousand tonnes and, once they settled on their final trajectories, travelling at two hundred and fifty kilometres a second. When they shot out of the Cache and into space, two of them were aimed roughly at the Earth–Moon system. The third was heading for Mars.

  For now, Poole could only fight to keep control of the craft, to keep it from s
lamming into the Cache wall – to find a way out of this box in the sky, before it sealed itself up again.

  More shock waves washed. The flitter bucked and rocked.

  Jack Grantt was braced against his couch. He yelled, ‘Some first contact!’

  33

  Once the flitter eased out of the lesion and rejoined the mother ship, the Bellona raced after the diamond missile from the Cache – the one that was heading to Mars. The Bellona’s GUTdrive was easily able to outrun the Probe’s two hundred and fifty kilometres per second, at which rate the diamond mass would take about eleven days to reach Mars itself.

  The Probe: that was what the Oversight groups and the official agencies were already calling it, and the term was spreading rapidly through the communities millions strong who were listening in, on Earth as well as Mars and elsewhere. But to an engineer that word implied a certain intention, Poole realised. If it was a probe, like his own Sun Probe, all it wanted, presumably, was information. Nothing more sinister than that about this Mars-bound mass, and its siblings heading for Earth and Moon.

  This interpretation was based only on hope. What was real and certain was that the object’s trajectory, without modification, would take it direct to an impact on Mars.

  An impact, it soon emerged, square in the heart of Hellas Planitia.

  Without waiting for orders, or consent, Nicola launched the Bellona on a parallel course.

  Two days out from Mars, Poole spoke to his colleagues on Gallia Three. Not that there was much to confer about.

  As far as anybody could tell, once the diamond lump was launched from the Cache, its trajectory was modified by no further propulsion system, either onboard or external. There was no flaring of exotic rocket exhausts from the Probe itself, no high-intensity laser beams pushing at the carbon lump as it sailed towards Martian space.