Seveneves

by Neal Stephenson

  Madam President was a little while parsing that and wasn’t sure if she liked it. Nervous at the silence, Zeke went on: “I’ll apologize in advance that I can’t stay for very long. I’m here with a specific job to do, and once it’s done, I need to move on.”

  “Inspecting Arklet 174 for possible damage from a microbolide strike,” Julia said.

  “Yes, ma’am.”

  “I called it in yesterday. I could have sworn I heard a loud banging noise. It scared me to death. But there doesn’t seem to be any damage. And the more time goes by the more I wonder if I just imagined it. Space is a noisy environment. I hadn’t expected that. The thrusters are so loud when they come on. Maybe it was nothing more than that. I would feel so embarrassed if I summoned you all the way out here to no purpose.”

  “Summoned me?” Zeke asked, a little bewildered. “The Incident Report System is an automatic queue; the assignments are handed out at random.”

  Julia exchanged a mischievous look with Spencer. “You and Spencer have been together on Izzy for more than two years,” she said. “I’m sure you’ve come to appreciate his skills—as have I.”

  Zeke looked just a bit queasy. “So you got in and manipulated the queue?”

  “Old habits die hard,” Julia said. “I’m accustomed to working with people I know and trust. If an inspection of my arklet is required, and someone has to do it, then why not have that someone be a person I have met before? Since the assignments are handed out at random, as you say, it might as well be you.”

  “Well,” Zeke said, “since you put it that way, I’m glad to be able to catch up with you for a few minutes, Madam President. Just saying that I’ll have to complete the full inspection anyway, so we can close the loop on your report.”

  “Of course, and I’ll bet it will go quickly,” Julia answered with a wink. “Zeke, you are a member of the General Population, are you not?”

  “Of course,” Zeke said. “As an original member of the ISS crew, that’s naturally . . .” but then his eyes strayed toward Spencer and his voice trailed off.

  Julia smiled. “An awkward topic has come up, and it’s best to face it with absolute transparency. Despite being a longtime, trusted member of the ISS crew, Spencer here has been removed from the General Population and demoted to the status of an Arkie.”

  “I wouldn’t look at it as a demotion,” Zeke began.

  Julia silenced him with a dismissive fluttering of the fingers. These were still manicured. Camila had been doing her nails for her. “We all know it was a demotion. Markus sprang it on Spencer when he got news of the Eight Ball and saw what was coming. Oh yes, I’ve been filled in on all of the carefully laid plans that Markus set into motion when his sweetheart so conveniently gave him the news. Had word of it reached us at the White House, I don’t know how I would have reacted—but we were busy protecting Kourou, and supporting Markus as best we knew how. Spencer here, after all those years of patient service, was replaced by that hacker boy—”

  “Steve Lake?” Zeke asked.

  Julia’s eyes darted to Camila, who nodded.

  “Yes,” Julia said, “Steve Lake. I guess he’s quite clever, but obviously no competition for Spencer.”

  “Are they in competition?” Zeke asked.

  “In a sense yes, when we Arkies are exposed to the all-seeing eye of SAN, and the GPop is permitted to have some semblance of privacy.”

  “It depends on where you are in the space station,” Zeke began, but then trailed off.

  “I wouldn’t know, since I’ve been permitted to spend very little time there. Oh, I know the official justification. I’m not qualified to be a member of the GPop. By process of elimination, that makes me an Arkie. Fine. But that doesn’t mean I can’t maintain a degree of social connection with old friends who are so privileged.” Julia reached out and clasped Zeke’s hand briefly.

  “To be sure,” Zeke said, “and I think that as time goes on those two populations will cease to be thought of as separate groups.”

  “I know that is the official dogma,” Julia said, amused.

  “But most of that social interaction is not going to be through face-to-face visits.”

  “So I’m told. Hard to envision how the populations will merge as long as that is the case.”

  “Most of it is going to be happening through Spacebook and Scape and whatnot,” Zeke went on, referring to the Cloud Ark versions of popular Internet communication apps. “At least until—”

  “Until we all ascend into heaven and live happily ever after as one big friendly Ark,” Julia said. “Zeke, you know space operations better than anyone. What is your opinion of the strategy that Markus has been foisting on us? The Big Ride? Even the name seems a bit suggestive, doesn’t it, of . . . I don’t know what.” She exchanged a look with Camila, who giggled at the witticism.

  Zeke looked around.

  “You don’t need to worry about that,” Julia reassured him.

  “About what?”

  “Markus’s surveillance network.”

  “SAN? I wasn’t worried about it,” Zeke protested. “Just thinking.”

  “About what, pray tell? Major Petersen, all kidding aside, I really am quite keen to hear your opinions as an expert.”

  “To tell you the truth, I’m thinking about how thin the walls of this pressure hull are,” Zeke said. “When you called in that bolide strike yesterday, you sounded pretty alarmed—I heard the message. Well, you had every reason to be alarmed. I do this for a living now—I go out and inspect these craters, big and small, that are piling up on our equipment. I patch holes, repair stuff that’s broken, and twice now I’ve had to handle fatalities. It’s no joke. If Markus sees an opportunity for us to ascend into heaven, as you put it, behind the shelter of Amalthea, well, I think it’s worth a try.”

  “Is Amalthea going to shelter us from the thickening atmosphere? Camila here has been reading the technical reports for me, which Spencer has been so good as to download from the server. She tells me it’s quite serious.”

  “The expansion of the atmosphere? It’s damn serious,” Zeke said. “But Izzy’s ballistic coefficient, with Amalthea attached, is huge. She can plow through some pretty thick air, and the rock will absorb all the heat. And arklets can ride along in her wake, like bicyclists drafting behind a truck.”

  “All of the arklets?”

  Zeke swallowed. “No. She doesn’t make a big enough bow wave to shield all of the arklets. Unless they fly so close together that Parambulator goes nuts.”

  “This is the part of Markus’s plan that I can’t understand,” Julia said. “What is to happen to all of the arklets that are not afforded the privilege of nestling into Amalthea’s wake?”

  “I don’t know all the details of the plan,” Zeke said. “It is fluid.”

  “Meaning, it’s not really a plan,” Julia said.

  “It depends on when Ymir gets back. What kind of condition she’s in. How much ice she has. Then we’ll make a plan.”

  “And is that to be a dictatorial process? Under the, whatever it’s called—the martial law thing?”

  “PSAPS,” Camila said.

  Zeke shrugged. “I don’t think Markus is going to put it up for a vote. He’ll get together with his brain trust and they’ll decide.”

  “Why bother consulting the brain trust?” Julia asked, as if the idea were a fascinating novelty.

  “To bring in different perspectives . . . make sure they’re not missing anything.”

  “Are there any Arkies in this brain trust, or are we expected to meekly accept its verdict?”

  Zeke was flummoxed. Had he been given the ability to rewind and replay the conversation, he would see that he’d been outmaneuvered. Lacking that perspective, he was tongue-tied for now.

  Julia wasn’t. “I ask only because I’ve been getting to know a lot of Arkies. I have nothing else to do. No duties. No applicable skills. I find that many of them crave a bit of society. It’s a natural human need, jus
t as much as sleep and exercise. So I talk to them—in person here on our little heptad, or through the channels you mentioned, the Spacebook and the Scape. These young people find it at least a novelty to have a conversation with a lonely and bored ex-president. My point being, Major Petersen, that our system worked. The Casting of Lots and the training camps produced the brightest collection of young talent it has ever been my privilege to encounter. They are brimming over with energy and ideas. These are the scarcest resources in our universe right now—scarcer than water, scarcer than living space. And as such I’d consider it a shame if their energy was wasted and their ideas were not taken into account by whatever smoke-filled room Markus assembles to make his plan—assuming he even survives what sounds to me like a somewhat harebrained endeavor.”

  THE CREW OF THE ORIGINAL JAMES CAIRD HAD USED CELESTIAL NAVIGATION to find their way across hundreds of leagues of stormy seas to the coast of South Georgia Island. The crew of the New Caird would have to do something similar. It was easier for them. The navigator on James Caird had had no choice but to await breaks in the ever-present cloud cover and snatch observations when he could, comparing them against a mechanical chronometer that he hoped was still telling true time. New Caird had better timepieces and a better view of the sky. In place of a sextant, they had a device consisting of a wide-angle lens and a high-resolution image sensor that could tell what direction it was aimed in just by comparing what it saw to an astronomical database stored in its memory. So they knew precisely how they were oriented in space, and how that orientation was shifting as the giant shard of ice to which they were attached progressed through the inexorable mathematics of its long ellipse. That, combined with direct measurements of Earth’s position, enabled Markus to calculate the parameters of their orbit and to reckon, with precision that grew each time he rechecked the figures, exactly how low they were going to go. Whenever Izzy was on their side of the planet, which was about half the time, they were able to get the latest figures from Doob concerning the expansion of the atmosphere.

  It was in combining those two sets of figures that pure Newtonian mechanics began to break down. For, in a traditional calculation of a space vehicle’s trajectory, one assumed no atmosphere and no extraneous forces resulting from it. But there was now no denying that Ymir would be going low enough to scrape the air. At a minimum, this meant it would experience some drag that would throw it off the course that Sean Probst had laid in. As these things went, drag wasn’t that difficult to calculate. Its effect on their course could be estimated. But because the ice shard wasn’t a symmetrical body, coming in straight, it was also going to generate some lift. Not a lot of lift—nothing like an airplane wing—but some. If that lift got aimed in the wrong direction it would make Ymir veer downward, like a stricken airplane going into its death spiral. But if they aimed it up, it would ease their passage by pushing them away from the Earth into an altitude where air was thinner. They would lose the benefit of lift then and drift back downward, but as the air got thicker, the lift would resume and push them back up. They might skip off the atmosphere several times during the hectic half hour when they were slingshotting around the world. The results would have been difficult to predict even if Ymir had been a traditional vehicle with a fixed and regular shape. But the shard was irregular. They didn’t have time to measure it and to feed the data into an aerodynamics simulator, so they could only guess how much lift it was going to produce. And when its leading edge and its underside began to plow through the air—even though the air might be so thin as to be indistinguishable, for most purposes, from a vacuum—it was going to heat up. Steam would rise from it, producing some amount of upward thrust, and its shape would change. So even if they had been able to simulate the shard’s aerodynamics, its lift and its drag, those numbers would quickly have become wrong during its first encounter with the upper air.

  Compared with all of those complexities, the fact that Ymir would be flying backward while operating a damaged, experimental nuclear propulsion system at maximum power seemed like a mere detail.

  Faced with so many imponderables, a well-managed aerospace engineering project would have called a halt to all further work and devoted several years to analyzing the problem down to its minutest detail, exposing pieces of ice to the blast of hypersonic wind tunnels, building simulations, and war-gaming possible alternative strategies. But by the time Markus understood the general shape of the problem, they had twenty-four hours remaining to perigee. The tangerine Earth had grown to the size of an orange. No power wielded by humans could prevent Ymir from passing around it and scraping the atmosphere. They couldn’t even ditch. New Caird, detached from Ymir, didn’t have enough propellant in her tanks to materially change her course and would end up going on the same ride anyway. So Markus made a reasonable guess as to what would be a good angle of attack—the orientation that Ymir would adopt vis-à-vis the atmosphere—and initiated a program of thruster firings that, over the course of half a day, swung the ponderous shard around into the position he deemed best.

  Ymir’s “stern” was now aimed in the direction of movement, the huge mouth of the nozzle aimed forward so that it could make the all-important braking burn. But she was now twisted about her long axis in such a way that New Caird, still docked up near the “bow,” and projecting from the side of the shard at approximately a right angle, was on the zenith. This meant that during the passage of the high atmosphere her view of the Earth below would be blocked by Ymir, the nozzle of her engine pointed “up” toward the stars. Firing that engine would therefore tend to rotate the bow downward and the stern up, an attitude likely to produce more lift and help get Ymir out of trouble. Were the shard to tumble the other direction, it could end up in a position that would yield much more drag and much less lift, pulling the whole contraption deep into the atmosphere. In effect New Caird had been reduced to the status of a small attitude control thruster. It was a thruster that could only push in one direction, and so Markus had picked out the direction most likely to be useful if things began to go sideways. Vyacheslav would ride it out in New Caird’s pilot’s seat, from which he would enjoy an arm’s length, tunnel-vision view of some dirty, five-billion-year-old ice. He would wait for a verbal command from Markus, ensconced in Ymir’s common room, to fire New Caird’s main propulsion if needed.

  All of this was mere background noise to Dinah, who was entirely consumed with coordinating the efforts of robots. The number of Nats was in the tens of thousands. They could only be talked to collectively, as swarms. Trying to address and control them one by one, while theoretically possible, was a mug’s game. Their general task was to morph the shard.

  One swarm would be working on the inner surface of the nozzle bell. At the moment, all of those were out on the back end of the shard, sunning themselves to build up their internal reserves of power. At a signal from Dinah they would all converge on the circular maw of the nozzle, climb down into the bell, and spread out to reshape it as needed during the burn. They’d be running a program that Larz had developed and tweaked. So all Dinah really needed to do was to turn them on.

  Likewise, the smallest of the three swarms was down inside the ice hoppers, running Larz’s program for keeping rocks away from the augers. Working in the dark, these had to sip power from electrical taps that Ymir’s crew had installed for that purpose.

  The largest of the three swarms, though, was responsible for sculpting the interior of the big shard as it was hollowed out. By the time the journey to Izzy was finished, most of the ice would have been fed into the hoppers and blown out the nozzle, leaving a hollowed-out shell with just enough internal structure to hold the reactor in place and maintain some semblance of a nozzle bell. This was not as crazy as it sounded, for two reasons. First, it was what miners had done since time immemorial. They didn’t just hollow out mountains, since that would lead to collapse. They sculpted the mountains into structurally sound architectural systems, complete with pillars, arches, and vaults. This wa
s just that, except that the material was ice, and the forces in general were not as large. Secondly, most of the shard’s interior was of little consequence from a structural engineering standpoint. There was a reason why airplanes and race cars had been hollow shells—all skin and no bones. Most structural forces were naturally transmitted through the outermost layer of the vehicle, so that was the best place to put the strength. Enough strength on the outside made it possible to leave the inside hollow.

  Ice, of course, wasn’t the best material to work with. It was brittle. But the Ymir expedition had shipped out carrying a large supply of high-strength plastic cord, net, fabric, and loose fiber. And during the months that it had been coasting in from Grigg-Skjellerup, Larz’s robots had been at work converting ice into pykrete. That outer layer of visually black ice was no longer ice per se, but a synthetic material with much better structural properties. Frozen, it could stop bullets. Melted and strained, it would separate into water, artificial fibers, and black crud from the dawn of the solar system. In any case the larger robots—the Grabbs and the Siwis—responsible for doing most of the heavy material removal on the inside could scrape to within a few meters of that outer skin without compromising Ymir’s structure. It was the responsibility of the third Nat swarm to clean up after them and maintain the internal pillars and webs that would keep the reactor and the hoppers suspended in the middle of the hollow shard. This swarm-based ice-sculpting algorithm had been Larz’s invention, and he’d had a couple of years in which to perfect it, but Dinah was in charge of it now, and had a lot of learning to do between now and when she became fully responsible for it.

  Outnumbered by the Nats, but responsible for moving a much larger tonnage of ice, were the hundred or so Grabbs and Siwis, now mostly stationed at the ready around the shard’s interior. Most of these were general-purpose robots with some added-on bits that made them good at moving on ice, but there were also half a dozen Leatherface machines: upsized Grabbs with shovel-studded chain saws for limbs, made to move a lot of ice in a hurry. These were so good at their jobs that they tended to destroy their surroundings, so they had to move frequently. Each one had to be followed around by an entourage of smaller robots cleaning up its mess and getting it anchored to fresh locations.