Exultant

by Stephen Baxter

  Nilis told them that the cost of the Project, especially this latest phase, was continually questioned in the remote reaches of Coalition councils, but he was driving it through. “You can fill Sol system with theories and arguments,” he said. “But, my eyes, I’ve learned what makes these politicos tick. Dry-as-Martian-dust bureaucrats they may be, but there’s nothing like a bit of live technology to make them sit up and take notice! It’s the allure of war, you know, the pornography of destruction and death: that’s what motivates them—as long as it is somebody else’s death, of course.”

  The ensigns had to take Nilis’s word for that. But his clarity of purpose as this new phase of his project began was undeniable.

  A Navy facility was put at their disposal. It turned out to be a small disused dock in orbit around the bristling fortress world of Saturn, under the overall control of Commander Darc. Once it got underway, the development progressed rapidly, because the engineers were keen. Across the Galaxy, combat technology was pretty much static, and the crew, being engineers, enjoyed the challenge of putting together something new.

  From the first Virtual sketches of how a standard greenship might be modified, and the first simulations of how such a beast might handle in flight, the two ensigns immersed themselves in the work. Torec applied the crude management techniques she had learned on the Moon, and the complex project ran reasonably smoothly from the start. Pirius felt comparatively at home here among Navy engineers, far removed from such horrors as reincarnated Silver Ghosts.

  So Pirius was infuriated when Nilis called him away for yet another new assignment.

  Nilis had taken himself off to the heart of Sol system once more, to initiate studies on the nature of the Prime Radiant itself. It was his way; now that the test program was underway, he regarded the gravastar work as “mere detail,” and had switched his attention to the next conceptual phase of his project, the assault on Chandra itself. And he needed Pirius, Nilis said; he wanted one of his “core team” to be involved in every phase of the project—and Torec’s newfound management skills were just too valuable on the test-flight work; it was Pirius who could be spared.

  And so he summoned Pirius to what he called the “neutrino telescope,” before carelessly leaving Pirius to sort out his own travel. It was maddening—and embarrassing. Pirius had no real idea what neutrinos were, or why or how you would build a telescope to study them, or why Nilis felt neutrinos had anything to do with his project.

  But his biggest problem was figuring out where the telescope was.

  He asked around the Navy facility. None of the engineers and sailors knew what he was talking about. In the end, Pirius was forced to go to Commander Darc—another loss of face. “Oh, the carbon mine!” Darc said, laughing. He said the crew he would assign to Pirius would know where they were going.

  Pirius spent a last night with Torec. They shared a bunk in a Navy dorm that was big and brightly lit: not as immense as the Barracks Ball of Arches Base, but near enough to feel like home. They talked about inconsequentials—anything but Silver Ghosts or neutrinos, or their own hearts, or other mysteries.

  Then Pirius sailed once more into the murky heart of Sol system.

  The corvette he took was spartan compared to Nilis’s, and the crew, hardened Navy veterans irritated at being given such a chore, ignored Pirius for the whole trip. Pirius ate, slept, exercised. It wasn’t so bad; perhaps he was getting used to the strange experience of being alone.

  In its final approach the corvette swept around the limb of the planet, approaching from the shadowed side, and the new world opened up into an immense crescent.

  Pirius peered out of the transparent hull. The light was dazzling; he was actually inside the orbit of Earth here, and the sun seemed huge. Another new planet, he thought wearily, another slice of strangeness.

  But this one really was extraordinary. Under a thick, slightly murky atmosphere, the ground was pure white from pole to equator, and from orbit it looked perfectly smooth, unblemished, like an immense toy. He had never seen a world that looked so clean, he thought, so pristine. The whole surface even seemed to sparkle, as if it were covered in grains of salt.

  The corvette entered low orbit and the planet flattened out into a landscape. The air was tall, all but transparent, without cloud save for streaks of high, icy haze. But Pirius saw contrails and rocket exhausts, sparking through the air’s pale gray. Once he saw an immense craft duck down from orbit to skim through the upper atmosphere. It was a kind of trawler; air molecules were gathered into a huge electromagnetic scoop, its profile limned by crackling lightning.

  This close, though, the geometric perfection of the world was marred by detail. Pirius made out the shapes of mountains, canyons, even craters. But everything was covered by white dust, every edge softened, every profile blurred. Pirius wondered if the white stuff could be water ice, or even carbon dioxide snow, but the sun’s heat was surely too intense for that.

  Small settlements studded the land. Around these scattered holdings, quarries had been neatly cut into the creamy ground, their floors crisscrossed by the tracks of toiling insect-like vehicles. Tiny craft rose into space from small, orange-bright landing pads, carrying off the fruit of the quarries. Many of the buildings were themselves covered with white dust; evidently some of them were ancient.

  Pirius asked the Navy crew what the white dust was. Their reply was blunt: “Chalk,” a word that meant nothing to Pirius. But they called this world “the carbon mine,” as Darc had. It was only later that Pirius learned that this “carbon mine” had once had a name of its own, an ancient name with nothing to do with the purposes to which the planet had been put. Once, it had been called Venus.

  “So, another stop on your grand tour of Sol system, Ensign Pirius?”

  “It’s not by choice, Commissary.”

  “Of course. Well, come along, come along …” Nilis led the way along bare-walled corridors, padding over floors rutted by long usage.

  Nilis was working in an orbital habitat; the corvette had cautiously docked at the heart of a sprawling tangle of modules, walkways, and ducts. The habitat was devoted to pure science, it seemed; to the planet’s secondary role as a “neutrino telescope.” And it was old: the modules’ protective blankets were cratered by micrometeorite impacts, and blackened by millennia of exposure to the hard light of the sun.

  Within, the facility was a warren of corridors and small cylindrical chambers. Over a stale human stink, there was a lingering smell of ozone, of welding and failing electrical systems. The station had reasonably modern position-keeping boosters, inertial control, life support and other essential systems, but everywhere you looked maintenance bots toiled to keep the place going. The power nowadays came from a couple of GUT modules, but the habitat still sported an antique set of solar-cell wings, its glossy surfaces long since blackened and peeled away.

  Nilis said that, as a pure science facility, without obvious military potential, this place had always been starved of resources. “You get used to it,” he said.

  He brought Pirius to an observation module. They peered out at the gleaming face of the planet, and Pirius was dazzled. But he could make out the tracery of quarries and roads on the shining surface, and the steady streams of shuttles flowing through the atmosphere.

  Nilis said conspiratorially, “I rather like it here. But it’s not a happy place to work. On Pluto, say, you’re truly isolated, out in the middle of nowhere. But here, Earth is close enough to show as a double planet to the naked eye—close enough to touch. Nobody wants to work in a place like this, when home is so temptingly close.”

  Pirius ventured, “Venus is a carbon mine.”

  “Yes. Though nobody calls it Venus anymore. Nobody but Luru Parz and her kind.”

  Pirius knew enough basic planetology to understand that this planet must have been heavily transformed. It was a rocky world not much smaller than Earth, and this close to its parent sun it should have been cloaked with a thick layer of air,
a crushing blanket of carbon dioxide and other compounds baked out of the rocks by the sun’s relentless heat.

  Well, the atmosphere had once been over two hundred kilometers thick, Nilis said; it had massed about a hundred times as much as Earth’s, and had exerted a hundred times as much pressure at the surface. The bottom twenty kilometers or so had been like a sluggish ocean, and the rocks beneath had been so hot they had glowed red. That was the planet humans had first visited—and in those days the clouds were so thick that no human eye had ever seen the ground.

  “Venus was infuriating. A world so close to Earth, and so similar in broad numbers, but so different. For instance there’s actually no more carbon dioxide on Venus than on Earth; but on Earth it is locked into the carbonate rocks, like limestone; here it was all hanging lethally in the air. So what do you do?

  “In the early Michael Poole days, there were all sorts of schemes for terraforming Venus, for making it like Earth. Perhaps you could seed that thick air with nanobots or engineered life-forms, and use the sun’s energy to crack the useless carbon dioxide into useful carbon and oxygen. Fine! But there was so much air that you’d have finished up with a planet covered in a hundred-meter layer of graphite—and about sixty atmospheres worth of pure oxygen. Any human foolish enough to step out on the surface would have spontaneously combusted!

  “So then there were mega-engineering proposals to blast that annoying blanket of air off the planet altogether, with bombs, or even asteroid strikes. Happily somebody had a brighter idea.”

  It was realized that carbon was actually a vitally useful element—and the air of Venus contained the largest deposit of carbon in the inner system, larger than that of all the asteroids combined. It would be criminally wasteful to blast it away. So a new scheme was concocted, the planet seeded with a different sort of engineered organism.

  “They drifted through the high clouds,” Nilis said, “little bugs living in acidic water droplets, fed by photosynthesis. And they made themselves shells of carbon dioxide—or rather, of carbon dioxide polymers, cee-oh-two molecules stuck together in complex lattices.” The nanotech that enabled these engineered bugs to make their shells was based on the technology of an alien species called the Khorte, long Assimilated. “It was one of the first applications of alien technology inside Sol system,” Nilis said. “And it worked. When each little critter died, its shell was heavy enough to drift down out of the clouds toward the ground, taking with it a gram or two of fixed carbon dioxide.”

  Pirius saw the idea. “The carbon snowed out.”

  “Yes. On the ground, as it compressed under its own weight, it melted and amalgamated, and even more complicated polymers were formed. Those who mine the stuff call it chalk; something similar forms at the bottoms of Earth’s seas.

  “It was a very long-term proposition, one of humanity’s first mega-projects. But the cost was modest; you only had to pay for the first generation of engineered bugs. The project has now been going on for twenty thousand years—at least that long; it was founded by the ancients, it’s believed, in the days even before the Qax Occupation.”

  Once Venus’s carbon had been locked up in the convenient form of the chalk, it was easily mined, and had a myriad possible uses. But, said Nilis, it was only after the first few thousand years of the project that an unexpectedly useful application of Venus’s new crust of carbon dioxide polymers was discovered. “It turned out that some of the structures formed, in the hot, compressed layers of Venus chalk, had very interesting properties indeed.”

  Pirius took a guess. “You’re talking about neutrinos.”

  “Yes.”

  Neutrinos were exotic subatomic particles. Like ghosts, they passed through matter, through Pirius’s own body, or even the bulk of a world like Venus, barely noticing that anything was in the way. “And that makes them rather hard to observe,” said Nilis.

  Which was where Venus’s chalk came in. It was found that some of the more exotic polymers formed at high temperature and pressure in Venus’s gathering chalk layers were good at trapping neutrinos—or rather, traces of their passage.

  Neutrinos took part in nuclear reactions: when atomic nuclei fissioned or fused, releasing floods of energy in the process. Nilis said, “There are two places in nature where such reactions are commonplace. One was in the first few minutes of the formation of the universe itself—the moments of nucleosynthesis, when primordial baryonic particles, protons and neutrons, combined to form the first complex nuclei. The other is in the center of the stars, which run on fusion power. So, you see, a neutrino telescope can see into the fusing heart of the sun.”

  So Venus was given a new role: as a watchtower.

  “The ancients believed a deep monitoring of the sun was important—but not for the sun itself. Stars are pretty simple machines, really, much simpler than bacteria, say, and were thoroughly understood long before the first extrasolar planet was visited. No, it wasn’t the sun they were interested in but what lay within the sun. Dark matter,” Nilis said. “That’s what Michael Poole’s generation were watching. Dark matter, in the center of the sun …”

  As the sun swept through its orbit around the center of the Galaxy, it encountered dark matter. Almost as ghostlike as neutrinos, much of it simply passed through the sun’s bulk. But some interacted with the dense, hot stuff at the center of the sun, and losing energy, was trapped. Nilis said, “It orbits, lumps of dark matter orbiting the sun, even within the fusing heart of the star. Remarkable when you think about it.”

  It was this strange inner solar system of dark matter, entirely contained within the bulk of the sun, that the Venus facility had been designed to study. The dark-matter particles would annihilate each other, and in doing so released more neutrinos, to be trapped at Venus and analyzed.

  “I’ve glanced at the data streams,” Nilis said. “You can see structure in there: clumps, aggregates—even what looks like purposeful motion. There are some who speculate there is life in there, life-forms of dark matter. Why not, I say?”

  Pirius was baffled. “What harm can a trace of dark matter do?”

  “I don’t know,” said Nilis honestly. “The ancients obviously feared it, though. I’ve seen hints in the Archive of much more ambitious projects than this: engineered humans injected into the dark matter streams in the heart of the sun, and so on.”

  And Luru Parz, Pirius thought, who might herself be a survivor of those ancient times, still watched dark matter at the other extreme of Sol system. Here was another deep secret, another ancient fear.

  “Commissary, you aren’t interested in what’s going on in the sun.”

  “No. But I am interested in primordial nucleosynthesis.” That was the other source of neutrinos. He was talking about the Big Bang.

  As the universe expanded from its initial singularity, Nilis said, physics evolved rapidly. In the first microsecond, space was filled with quagma, a swarming magma of quarks, as if the whole universe was a single huge proton. But the universe expanded and cooled, and by the end of the first second most of the quarks had been locked up into baryonic particles, protons and neutrons. For the next few minutes, the universe was a ferocious cauldron of nuclear reactions, as evanescent atomic nuclei formed, almost immediately breaking up again, unstable in the ferocious heat. Neutrinos took part in this shatteringly rapid dance.

  But then, as the temperature dropped further, simple nuclei like helium suddenly became stable. The universe froze out. Just three minutes after the singularity this flurry of nucleosynthesis was over, and expanding space was filled with hydrogen and helium. There would be no more baking of nuclei until much later in the life of the universe, when the first stars formed.

  “And with no more nucleosynthesis,” said Nilis, “the primordial neutrinos no longer interacted with matter. To them the universe, at three minutes old, was already just about transparent. Those ancient neutrinos still drench space even today. Now, Venus was designed to watch neutrinos from the sun—”

&nb
sp; “But a neutrino is a neutrino,” Pirius said.

  “Yes. And in those primordial neutrinos can be read a story of the earliest moments of the universe. And it is a story of life, Ensign.”

  “Life?”

  “Quagmites.”

  It had actually been the analysis of the damage suffered by Pirius Blue’s greenship, the Assimilator’s Claw, that had prompted Nilis to come here to Venus, to start thinking about neutrinos.

  “It was I who ordered that your ship be subject to a proper forensic examination,” he said. “After all, it had been in close proximity to the Xeelee—not to mention a magnetar! I believed your ship might carry traces of its adventures from which we might learn more. And so I wanted it to be given more than a cursory glance in an Engineering Guild repair shop.”

  What Nilis’s scientists had discovered had not, in the event, been about the Xeelee at all, or even the magnetar. It was quagmites.

  Nilis said, “Have you really never wondered what quagmites actually are? And how they come to be so attracted to GUT energies?”

  “No,” Pirius said honestly. To pilots, quagmites were just an odd kind of virus which gave you trouble if you used a GUTdrive anywhere in the Central Star Mass. Since GUTdrives were essentially an obsolete technology, carried as backup in case more effective sublight-drive systems failed, nobody ever gave quagmites much thought.

  “Yes, yes, I understand your point of view,” Nilis said. “You aren’t even interested in the fact that these things are so obviously alive, are you?”

  Pirius shrugged. Life in itself wasn’t very interesting; as mankind had moved across the face of the Galaxy, life had been discovered everywhere.

  “Pirius, when its GUTdrive lit up, the Claw was peppered by small, but dense projectiles.” He clapped his hands and produced a Virtual image of the greenship. A translucent cutaway, it was laced through by a complex tracery of shining straight lines. “You were shot up, as if you had flown through a hail of bullets. The particles were bits of quagma, and they left tracks like vapor trails in the matter they passed through. The scars cut through everything—the hull, the equipment, even the bodies of you and your crew. But those greenships are tough little vessels; your systems took a lot of damage, but there was enough redundancy to see you through.”