Manifold: Space

by Stephen Baxter

Rendezvous with the hurtling rock was difficult. The Gurrutu couldn't muster the velocity change required to match Nereid's crashing orbit. So Madeleine had to burn her engines and use tethers, harpooning this great rock whale as it hurtled past, letting her ship be dragged along with it. Gurrutu suffered considerable damage, but nothing significant enough to make Madeleine abort.

  She entered a loose, slow orbit, inspecting the moon's surface. Nereid was uninteresting: just a misshapen ball of dirty ice, pocked by craters; it was so small it had never melted, never differentiated into layers of rock and ice like Triton, never had any genuine geology. Nereid was a relic of the past, a ruin of the more orderly moon system that had been wrecked when Triton was captured.

  But, despite its small size, it massed as much as 5 percent of Triton's own bulk. And where Triton's orbit, though retrograde, was neatly circular, Nereid followed a wide, swooping ellipse, taking almost an Earth year to complete a single one of its "months" around Neptune.

  Nereid could be driven head-on into Triton. It would be a useful bullet.

  She navigated with automatic star trackers, with radio Doppler fixes on Kasyapa, and by eye, using a sextant. Her purpose was to check the trajectory of the little moon, backing up the automated systems with this on-the-spot eyeballing, which, even now, was one of the most precise navigation systems known.

  Nereid was right on the button. But this game of interplanetary pool was played on a gigantic table, and Triton was a small target. Even now, even so close, Nereid could be deflected from its impact.

  At times the cold magnitude of the project – sending one world to impact another – awed her. This is too big for us. This is a project for the arrogant ones: the Gaijin, the others who strangled Venus and Triton.

  But when she was close enough, she could see the glow of engines on Nereid's far side: engines built by humans, placed by humans. Placed by her. She clung to her anger, seeking confidence.

  Even now Ben debated the ethics of the situation with his people. Most people here had been born long after the emigration: born in the caverns of Kasyapa, now with children of their own. To them, Madeleine and Ben Roach were intruders from the muddy pool at the heart of the Solar System, invaders from another time who proposed to smash their world. The shortness of human lives, she thought. Our curse. Every generation thinks it is immortal, that it has been born into a world that has never changed, and will never change.

  She dozed in her sleeping compartment, a box little larger than she was. Inside, however, tucked into her sleeping bag with the folding door drawn to, she felt comfortable and secure. She would track Nereid as long as she could, guiding it to its destination, unless she was ordered to stand down.

  She got a number of direct calls from Nemoto that she did not accept. Nemoto was irrelevant now.

  At the very last minute Ben came through.

  Somewhat to her surprise, the colonists had agreed to let the project go ahead. Ben would arrange for the temporary evacuation of the colonists from Kasyapa, to the hulks of the old transport ships still in orbit, now drifting without their engines.

  "Lena is pleased," he told her.

  "Pleased?"

  "By your reaction to the crystal shell around the core. The ice eight. She wanted to make you angry. If the project succeeds then the crystal shell will be destroyed. And the last trace of the native life will surely be destroyed with it."

  Madeleine growled. "I know, Ben. I always knew. The Triton bugs lost their war a long time ago, before they even had a chance to voice an opinion. Their memory should motivate us, not stop us. The crystal builders have gone, but the Gaijin are on their way, here, now. Well, the hell with them. This is the trench we've dug, and we aren't going to quit it."

  "If," he said, "the Gaijin are the true enemy."

  "They will do for now."

  He smiled sadly. "You sound like Nemoto."

  "None of us age gracefully. Why didn't you tell me about the native life, Ben?"

  His virtual image shrugged. "Not everybody who's grown up here knows about it. Life is hard enough here without people learning that there is an alien artifact of unknown antiquity buried at the heart of the world."

  She nodded. And yet he hadn't answered her question. Despite all we've been through – even though we're both refugees from another age, and we traveled to the stars together – I'm not close enough for you to share your secrets.

  At that moment, she felt the ties between them stretch, break. Now, she thought, I am truly alone; I have lost my only companion from the past. It was surprising how little it hurt.

  "Here is another possibility," Ben said. "Beyond ethics, beyond this perceived conflict with the Gaijin. You like to meddle, to smash things, Madeleine. You are like Nereid yourself, a rogue body, come to smash our little community. Perhaps this is why the plan is so appealing to you."

  "Perhaps it is," she said, irritated. "You'll have to judge my psychology for yourself."

  And with an angry stab, she shut down the comms link.

  Alone in Gurrutu, she assembled a complete virtual projection of Triton, a three-dimensional globe a meter across. She looked for the last time at the ice surface of Triton, the subtle shadings of pink and white and brown.

  She switched to a viewpoint at Triton's evacuated equator. It was as if she were standing on Triton's surface.

  Nereid was supposed to do two things: to spin up Triton, and to melt its ancient oceans. Therefore she had steered the moon to come in at a steep angle, to deliver a sideways slap along Triton's equator. And so, when she turned her virtual head, Nereid was looming low on the horizon: a lumpy, battered moon, visibly three-dimensional, rotating, growing minute by minute.

  An icon in the corner of her view recorded a steady countdown. She deleted it. She'd always hated countdowns.

  Her imaging systems picked out Gaijin flower-ships in low orbit around the moon, golden sparks arcing this way and that. She smiled. So the Gaijin were curious too. Let them watch. It would be, after all, the greatest impact in the Solar System since the end of the primordial bombardment.

  Quite a show. And for once it would be humans lighting up the sky.

  The end, when it came, seemed brutally fast. Nereid grew from a spot of darkness, to a pebble, to a patch of rock the size of her hand, to, Jesus, a roof of rock over the world, and then –

  Blinding light. She gasped.

  The image snapped back to an overview of the moon. She felt as if she had died and come back to life.

  A plume of fragments was rising vertically from Triton's surface, like one last mighty geyser: bits of red-hot rock, steam, glittering ice, some larger fragments that soared like cannonballs.

  Nereid was gone.

  Much of the little moon's substance must already have been lost, rock and ice and rich organic volatiles blasted to vapor in that first second of impact: lost forever, lost to space. Perhaps it would form a new, temporary ring around Neptune; perhaps eventually, centuries from now, some of it would rain back on Triton, or some other moon.

  This was an astoundingly inefficient process, she knew, and that had been a key objection of some of the Kasyapa factions. To burn up a moon, a whole four-billion-year-old moon, for such a poor gain is a crime. Madeleine couldn't argue with that.

  Except to say that this was war.

  And now something emerged from the base of the plume. It was a circular shock wave, a wall of shattering ice like the rim of a crater, plowing its way across the ground. The terrain it left behind was shattered, chaotic, and she could see the glint of liquid water there, steaming furiously in the vacuum and cold. Ice formed quickly, in sheets and floes, struggling to plate over the exposed water. But echoes of that great shock still tore at this transient sea, and immense plates, diamond white, arced far above the water before falling back in a flurry of fragments.

  Now, in that smashed region – from cryovolcanoes kilometers wide – volatiles began to boil out of Triton's interior: nitrogen, carbon dioxide, methane,
ammonia, water vapor. Nereid's heat was doing its work; what was left of the sister moon must be settling toward Triton's core, burning, melting, flashing to vapor. Soon a mushroom of thickening cloud began to obscure the broken, churning surface. Some of the larger fragments thrown up by that initial plume began to hurtle back from their high orbits and burn streaks through Triton's temporary atmosphere. And when they hit the churning water-ice beneath, they created new secondary plumes, new founts of destruction.

  The shock wall, kilometers high, plowed on, overwhelming the ancient lands of ice, places where nitrogen frost still lingered. It was not going to stop, she realized now. The shock would scorch its way around the world. It would destroy all Triton's subtlety, churning up the nitrogen snows of the north, the ancient organic deposits of the south, disrupting the slow nitrogen weather, destroying forever the ancient, poorly understood cantaloupe terrain. The shock wall would be a great eraser, she thought, eliminating all of Triton's unsolved puzzles, four billion years of icy geology, in a few hours.

  But those billowing ice-volcano clouds were already spreading in a great loose veil around the moon, the vapor reaching altitudes where it could outrun the march of the shattered ice. Mercifully, after an hour, Triton was covered, the death of its surface hidden under a layer of roiling clouds within which lightning flashed, almost continually.

  She heard from Ben that the Yolgnu were celebrating. This was Triton Dreamtime, the true Dreamtime, when giants were shaping the world.

  After three hours there was a new explosion, a new gout of fire and ice from the far side of the moon. That great shock wave had swept right around the curve of the moon until it had converged in a fresh clap of shattered ice at the antipode of the impact. Madeleine supposed there would be secondary waves, great circular ripples washing back and forth around Triton like waves in a bathtub, as the new ocean, seething, sought equilibrium.

  Nemoto materialized before her.

  "You improvised well, Madeleine."

  "Don't patronize me, Nemoto. I was a good little soldier."

  But Nemoto, of course, five hours away, couldn't hear her. "...Triton is useless now to the Gaijin, who need solid ice and rock for their building programs. But it is far from useless to humans. This will still be a cold world; a thick crust of ice will form. But that ocean could, thanks to the residual heat of Nereid and Neptune's generous tides, remain liquid for a long time – for millions of years, perhaps. And Earth life – lightly modified anyhow – could inhabit the new ocean. Deep-sea creatures – plankton, fish, even whales – could live off the heat of Triton's churning core. Triton, here on the edge of interstellar space, has become Earthlike. Imagine the future for these Aborigines," Nemoto said seductively. "Triton was the son of Poseidon and Aphrodite. How apt..."

  This was Nemoto's finest hour, Madeleine thought, this heroic effort to deflect not just worlds, but the course of history itself. She tried to cling to her own feelings of triumph, but it was thin, lonely comfort.

  "One more thing, Meacher." Virtual Nemoto leaned toward her, intent, wizened. "One more thing I must tell you..."

  Later, she called Ben.

  "When are you coming home?" he asked.

  "I'm not."

  Ben frowned at her. "You are being foolish."

  "No. Kasyapa is your home, and Lena's. Not mine."

  "Then where? Earth? The Moon?"

  "I am centuries out of my time," she said. "Not there either."

  "You're going back to the Saddle Points. But you are the great Gaijin hater, like Nemoto."

  She shrugged. "I oppose their projects. But I'll ride with them. Why not? Ben, they run the only ship out of port."

  "What do you hope to learn out there?"

  She did not answer.

  Ben was smiling. "Madeleine, I always knew I would lose you to starlight."

  She found it hard to focus on his face, to listen to his words. He was irrelevant now, she saw. She cut the connection.

  She thought over the last thing Nemoto had said to her. Find Malenfant. He is dying...

  Chapter 23

  Cannonball

  It had to be the ugliest planet Madeleine had ever seen.

  It was a ball the size of Earth, spinning slowly, lit up by an unremarkable yellow star. The land was a contorted, blackened mess of volcano calderas, rift and compression features, and impact craters that looked as if they had been punched into a metal block. Seas, lurid yellow, pooled at the shores of distorted continents. And the air was a thin, smoggy, yellowish wisp, littered with high mustard-colored cirrus clouds.

  On the planet there were no obvious signs of life or intelligence: no cities gleaming on the dark side, no ships sailing those ugly yellow oceans. But there were three Gaijin flower-ships in orbit here, Madeleine's and two others.

  Her curiosity wasn't engaged.

  All the Gaijin would tell her about the planet was the name they gave it – Zero-zero-zero-zero – and the reason they had brought her here, across a hundred light-years via a hop-skip-jump flight between Saddle Point gateways in half a dozen systems, a whole extra century deeper into the future: that they needed her assistance.

  Malenfant is dying.

  Reluctantly – after a year in transit, she had gotten used to her lonely life in her antique Gurrutu hab module – she collected her gear and clambered into a Gaijin lander.

  Madeleine stepped onto the land of a new world.

  Ridges in the hard crumpled ground hurt her feet. The air was murky gray, but more or less transparent; she could see the Sun, dimmed to an unremarkable disc as if by high winter cloud. Immediately she didn't like it here. The gravity was high – not crushing, but enough to make her heavy-footed, the bio pack on her back a real burden.

  Numbers scrolling across her faceplate told her the gravity was some 40 percent higher than Earth's. And, since this world was about the same size as Earth, that meant that its density had to be around 40 percent higher too: closer to the density of pure iron.

  Earth was a ball of nickel-iron overlaid by a thick mantle of less dense silicate rock. The high density of this world must mean it had no rocky mantle to speak of. It was nickel-iron, all the way from core to surface, as if a much larger world had been stripped of its mantle and crust, and she was walking around on the remnant iron core.

  That wasn't so strange. There are ways that could happen, in the violent early days of a system's formation, when immense rogue planetesimals continue to bombard planets that are struggling to coalesce. Mercury, the Solar System's innermost planet, had suffered an immense primordial impact that had left that little world with the thinnest of mantles over its giant core.

  At least human scientists had presumed it was primordial. Nobody was sure about such things anymore.

  She glanced around the sky. She was a hundred light-years from home, a hundred light-years in toward the center of the Galaxy, roughly along a line that would have joined Earth to Antares, in Scorpio. But the sky was dark, dismal.

  There were no asteroid belts, only a handful of comets left orbiting farther out, and two gas giants both stripped of their volatiles, reduced to smooth rocky balls. She was well inside the interstellar colonization wave front that appeared to be sweeping out along the spiral arm and was nearing Earth, a hundred light-years back. And this was a typical post-wave-front system: colonized, ferociously robbed of its resources by one shortsighted, low-tech predatory strategy or another, trashed, abandoned.

  Even the stars had been obscured, their light stolen by Dyson masks: dense orbiting habitat clouds, even solid spheres, asteroids and planets dismantled and made into traps for every stray photon. It was a depressing sight: an engineered sky, a sky full of scaffolding and ruins.

  Earth's sky was primeval, comparatively. This was a glimpse of the future, for Earth.

  She walked farther, away from the lander, which was a silvery cone behind her. She was only a few kilometers from the shore of one of those yellow seas; she figured it was on the far side of a l
ow, crumpled ridge.

  She reached the base of the ridge and began to climb. In the tough gravity she was given a good workout; she could feel her temperature rising, the suit's exoskeletal multipliers discreetly cutting in to give her a boost.

  She topped the ridge, breathing hard. A plain opened up before her: shaded red and black, littered by sand dunes and what looked like a big, heavily eroded impact crater. And off toward the smoky horizon, yes, there was that peculiar yellow ocean, wraiths of greenish mist hanging over it. It was a bizarre, surrealist landscape, as if all Earth's colors had been exchanged for their spectral complements.

  And, only a hundred meters from the base of the ridge, she saw two Gaijin landers, silver cones side by side, each surrounded by fine rays of dust thrown out by landing rockets. Beside one of the landers was a Gaijin, utterly still, a spidery statue. Next to the other stood a human, in an exo-suit that didn't look significantly different than Madeleine's.

  The human saw her, waved.

  Madeleine hesitated for long seconds.

  Suddenly the world seemed crowded. She hadn't encountered people since she had last embraced Ben, on Triton. She'd certainly never met another traveler like this, among the stars. But it must have taken decades, even centuries, for the Gaijin to organize this strange rendezvous.

  She began to clamber down the ridge toward the landers, letting the suit do most of the work.

  The waving human turned out to be a Catholic priest called Dorothy Chaum. Madeleine had met her before, subjective years ago. And inside one of the landers was another human, somebody she knew only by reputation.

  It was Reid Malenfant. And he was indeed dying.

  Malenfant was wasted. His head was cadaverous, the skull showing through thin, papery flesh, and his bald scalp was covered in liver spots.

  Dorothy and Madeleine got Malenfant suited up and hauled him to Dorothy's lander. In this gravity it was hard work, despite their suits' multipliers. But Dorothy's lander had a more comprehensive med facility than Madeleine's. Malenfant had nothing at all, save what the Gaijin had been able to provide.