Seveneves

  They were experiencing one gee—Earth-normal gravity—for the first time in over a year.

  Markus, who’d only been in orbit for a few days, sounded great. To judge from what they were hearing in their headsets, he had unstrapped from his pilot’s couch and was clambering all over Arklet 3 as if it were the Daubenhorn.

  Ivy and Dinah couldn’t move for several minutes, and Dinah seriously entertained the possibility that she was dying.

  “Can you pass out while you’re lying down?” she finally asked.

  “Remain in your positions,” a voice from Houston was saying, dimly, distantly, as if shouting at them through a bullhorn from four hundred kilometers below. “It is a long fall to the bottom of that arklet.”

  A long fall. Dinah had ceased to even think in terms of up and down. The concept of falling had become meaningless to her. When you were in orbit, you were always falling. But you never hit anything. She risked turning her head to look at the grate “below,” and that was the trigger that forced her to reach for her barf bag.

  DAY 333

  Doob had known for a while that he was not the easiest guy to be related to. During his last ten weeks on Earth, however, he sometimes feared he was pushing his family’s patience beyond human limits with his lust for camping.

  Until then, his idea of a satisfying outdoor experience had been to saunter out onto the terrace of a European hotel to smoke cigars and drink brandy. His duties as an astronomer sometimes called him to remote locations such as the summit of Mauna Kea, where he would dutifully go outside, freeze his ass off for a few minutes, remark on the awesomeness of the view and the clarity of the air, and then go back inside to sit behind a workstation and stare at images on a screen. Camping, and the outdoor life in general, simply hadn’t been a part of the culture of his family, which tended to look with favor on being under a sound roof, in a heated space, behind locked doors, with plenty of food baking and frying in a modern, fully appointed kitchen. He had always admired his colleagues in the life and earth sciences who could hit the road on short notice with a fully stocked backpack and live rugged adventuresome lives in exotic locales. But he had admired them from a distance.

  His sojourn to Moses Lake with Henry had turned him into a late convert to the outdoor life, and left him with a considerable stock of state-of-the-art gear that he was strangely eager to use. The visit to Bhutan had also been a trigger. This had been preceded by a lengthy series of flights across the Pacific and a brief stay on an aircraft carrier: cramped, crowded, artificial environments not unlike where he would be spending the remainder of his days. Then, just for a blessed few hours, he had climbed out of that chopper into the high, cold, piney air of Bhutan, and gone for a ramble in the king’s Land Rover, and hiked up a misty mountain that had struck him as being straight from a 1970s album cover. And he had done some introspection about the fact that he couldn’t even take such a lovely place at face value but only liken it to such pop culture references. A few hours later he had been back on the aircraft carrier with Dorji and Jigme and about a hundred other Arkers who had been collected in a similar manner from Myanmar, Bangladesh, Nepal, various provinces of India, Sri Lanka, and scattered island groups. He had been struck by the contrast between how centered, how natural, how autochthonous the Bhutanese youths had looked when he had first seen them on the side of the cliff in their home country, and how lost they appeared in the painted steel companionway of an aircraft carrier, mixed up with other South Asians in equally colorful garb, all equally alienated from their native soil, all looking for a place to stow their priceless cultural artifacts.

  He had come home with the idea in his head that he needed to get a little bit of native soil on himself before getting shot up to a place where he would be every bit as lost and alienated as Dorji and Jigme had been aboard USS George H. W. Bush. Which seemed uncontroversial to him. But when he presented the plan to Tav over a cup of naval coffee in one of the aircraft carrier’s eateries, Tav demurred. “You are totally overromanticizing dirt.”

  Tav liked to play the devil’s advocate. He and Doob had had many such conversations. Doob shrugged and said, “Let’s say you’re right. What’s the worst that could happen if I get some dirt on me while I still have access to dirt?”

  “Tetanus?”

  “Before they started sending me to places like this, they made sure I was up to date on my shots.”

  “No, seriously, I just don’t buy it, Doob.”

  “Buy what? What is it you think I’m trying to sell you?”

  “You’re trying to sell me the idea that there is such a thing as a state of nature that humans were designed to live in. It is the ‘dirt is good’ hypothesis.”

  “But obviously we evolved in rustic outdoor settings. Those places are, in some sense, natural to us.”

  “But we did evolve, Doob. We’re not animals. We evolved into organisms that could make things like this.” Tav waved his free hand around at the painted-steel environs of the aircraft carrier. “And this.” He raised his cup of coffee and clinked it against Doob’s.

  “Which is a good thing, you’re saying.”

  “Compared to being torn apart by hyenas? Yeah, obviously it’s a good thing.”

  “Well, I’m not going to get torn apart by hyenas. I’m just going to go camping.”

  Tav smiled in a way that seemed a little forced. You don’t get what I’m saying, do you? He said, “Look, you know my views on the Singularity. On uploading.”

  “I did blurb your book on the topic.”

  “Yes, thank you for that.” Tav was referring to the idea that the human brain could, in principle, be digitized and uploaded into a computer. That this would one day happen on a large scale. That it might actually have happened already—that we might all, in fact, be living in a giant digital simulation.

  Something occurred to Doob. “Is that why you were grilling the king about his views on reincarnation?”

  “That’s part of it,” Tav admitted. “Look, all I’m saying is that if you’ve gone where I’ve already gone, in terms of thinking about that—”

  “If you’ve drunk the Singularity Kool-Aid, in other words?” Doob said.

  “Yeah, Doob, as you know I’ve already done, then you’ve already made a fundamental break with trying to be Nature Boy. I am never going to be Nature Boy. I believe that the human mind is almost infinitely malleable and that people are going to adjust, within days or weeks, to life on the Cloud Ark. We will simply turn into a different civilization altogether from the one we grew up in. Our whole idea of nature will be forgotten. And a thousand years from now, people will go on ‘camping trips’ that will consist of sleeping in arklets, drinking Tang, and peeing into tubes just like their ancestors did.”

  “To them,” Doob said, “that’ll be a back-to-nature experience.”

  “I think that’s how we will see it, yes,” Tav said.

  Doob considered uttering the punch line to the famous joke: Who’s “we,” white man? But he thought better of it.

  For the next few weeks his duties had taken him to various other parts of the world, making what Mario the photographer referred to as “abduction runs” and conveying the victims to Arker training camps where they would spend the rest of their time on Earth playing elaborate video games about orbital mechanics. Tavistock Prowse showed up for some of these. When he wasn’t doing that, he was making social media posts about the themes he had articulated in his conversation on the aircraft carrier. And when Doob clicked through to those posts he was always impressed by the number of people who were reading them. Tav was developing a following, and a reputation as an important thinker about the sociology of the upcoming space-based civilization.

  Whenever Doob got a few days’ downtime, he would swoop down on a part of the country where one of his kids was living and grab them and take them camping.

  Henry had taken up residence at Moses Lake permanently, or as permanently as anything could be in this world. That was his yo
ungest. Hadley, the girl in the middle, was in Berkeley; she’d been doing volunteer work for an organization in Oakland and had a lot of free time. Doob would drag her away on day hikes to Mount Tam or longer sojourns in the Sierras. Hesper, his oldest, lived outside of D.C. with her boyfriend, a military man stationed at the Pentagon.

  The Last Camping Trip happened in early October. Doob still had a few weeks left, but he knew he would spend most of it in training, or talking about training on TV. In the weeks to come he might be able to play hooky and go out on the occasional afternoon hike. But the fact of the matter was that the next time he bedded down in a sleeping bag, it would be in zero gravity, in the cozy environs of a windowless aluminum can.

  Perhaps sensing that, Amelia had flown out on the spur of the moment. Normally she’d have been teaching school at this point in the year, but the schedule had become fluid. It was difficult to sustain the illusion that education was of value for kids who would not live long enough to use it. They’d never take the standardized tests that they were prepping for. In a way, Amelia had said, this had led to a kind of renaissance in pedagogy. Free from the constraints of racking up high test scores or getting into colleges, students could learn for learning’s sake—which was how it ought to be. The tick-tock curriculum had dissolved and been replaced by activities improvised from day to day by teachers and parents: hiking in the mountains, doing art projects about the Cloud Ark, talking with psychologists about death, reading favorite books. In one sense Amelia and her colleagues had never been more needed, never had such an opportunity to show their quality. At the same time, the routine had loosened up enough for Amelia to take a couple of days off, hop a plane to D.C., surprise Doob, and drive up into the mountains with him and Hesper and Enrique to enjoy the fall foliage.

  Doob had never made a real connection to Enrique—a half-black, half–Puerto Rican, all-American army sergeant from the Bronx. But now, sitting on the tailgate of a rented SUV, snuggled under a blanket with Amelia, looking out over a rolling mountain vista gorgeous with fall color, and waiting for some sausages to heat up on the hibachi, Doob felt as close to the guy as he could to anyone. Enrique seemed to sense the thawing in his mood.

  “What are you going to build up there?” he asked.

  It said something about how much Doob had changed in the last year that he didn’t let out a derisive snort. His face did not even change, or so he told himself. He looked over at Amelia, sitting next to him, for confirmation. She’d been trying to help Doob out. For the kids, she explained. It doesn’t matter what you think, Dubois, or what you feel. It’s not about you. It’s not even about science. Right now it’s about telling the kids in my classroom what it is that they have to hope for. So shut up and get it done.

  These things were important. It wasn’t just a matter of hiding what you really felt. If you hid your feelings well enough, it actually changed you. A few months ago Doob would have betrayed cynicism, possibly long enough for Enrique to notice it. And a few months before that he might have launched into a detailed explanation of why he was cynical, making it clear that the Cloud Ark was going to be an experiment in hastily improvised survival against nearly impossible odds.

  None of that happened. He looked at the faces of Enrique and of Hesper, lit on one side by blue twilight and on the other by the glow of the coals, and he answered the question. He answered it as if he were standing in front of a television camera streaming live to the Internet. “The resources up there are basically infinite. That was true even before the moon blew up. Now it has been busted open like a piñata. All it needs is to be shaped into the right architecture—enclosed habitations that we can fill with air and fertilize with the genetic heritage of the Earth. That’s going to take a while, and we’ll go through some tough times first. It’s going to be tough emotionally when the Hard Rain hits and we have to say goodbye to all that was. And it’s going to be tough afterward when the Arkers have to learn how to work together and make hard choices. By far the biggest challenge humanity has ever faced. But we’ll survive. We’ll use what’s up there to build incubators for Our Heritage to live in, to grow, and to improve on what we brought with us. And eventually the day will come when we return. The Hard Rain won’t last forever. Oh, it’ll last for many lifetimes—as long as human civilization has existed until now. And what it is going to leave behind will be a hot and rocky wasteland. But by that point many generations will have devoted all of their hopes and their creative genius to the problem of remaking the world as well as, or better than, what we see here. We will come back. And that’s the real answer, Enrique. Will we survive? Yeah. It’ll be touch and go, but we will survive. Will we build space habitats? Absolutely. Small ones at first, big ones later. But that’s not the real goal. The real goal will take thousands of years. The real goal is to build Earth again, and build it better.”

  It was the first time he’d said it this way. But it wasn’t the last. In the next few weeks—his last weeks on Earth—he’d say it again, to television cameras, to the president, to a stadium full of Arkers in training. All he knew at the time was that Enrique was nodding in a way that said It’s going to be okay, Doob’s got this, and Hesper was snuggling her head against Enrique’s powerful shoulder, eyes gleaming, staring into the future that her father was conjuring with those words.

  Behind her, a meteor knifed across the twilight sky and exploded out over the Atlantic.

  Cloud Ark

  Day 365

  “TODAY WE’RE GOING TO TALK ABOUT WHAT IT REALLY MEANS TO have a swarm of arklets in orbit,” said famous astronomer and science pundit Doc Dubois. He was hovering in the center of Arklet 2, currently docked to Izzy. He was wearing a pressure suit with its helmet detached and slung under his arm. He was talking into one of the arklet’s built-in high-def video cameras, trusting that some computer, somewhere, was recording the footage.

  “Cut,” he said. Then he felt a little sheepish. He was producing and editing his own videos now, so he had just said “cut” to himself. In space, there were no video crews, photographers, production assistants, or makeup artists to follow you around. He rather liked it that way. But there was something to be said for having at least one other human in the room who could react to what you were saying. He needed Amelia there, silently shaking her head or nodding. Instead of which he tried to imagine that he was talking to the kids in her classroom in South Pasadena on a sunny Tuesday morning. He replayed his own dialogue in their ears.

  What it really means sounded skeptical. As if everything said on the topic heretofore had been a bunch of BS. And in orbit wasn’t really necessary. Everyone knew that they were in orbit.

  “Today we’re going to talk about what it means to have a swarm of arklets,” he said. “In normal space, like on Earth, we use three numbers to tell where something is. Left-right, forward-back, up-down. The x, y, and z axes from your high school geometry class. Turns out that this doesn’t work so well in orbit. Up here we need six numbers to fully specify what orbit an object, such as an arklet, happens to be in. Three for position. But another three for velocity. If you’ve got two objects that share the same six numbers, they’re in the same place. Right now, my six numbers are the same as those of this arklet that I’m floating in, and so we’re moving through space together. But if one or more of my numbers changed, you’d see me drifting.”

  Doob had brought with him a small can of compressed air—a common convenience used by electronics technicians to blow dust away from things they were working on. He aimed it “down” toward the aft end of the arklet and pressed the button. Air hissed out and he began drifting “up” toward the front door. He raised a hand above his head in time to kill his upward motion against the forward bulkhead, then turned to look into a different camera.

  Good. It was the third time he’d attempted this, and he was running out of canned air.

  “I can’t drift far, confined as I am to the pressure hull. But you can imagine that if I hadn’t been able to stop—if I
’d been out on a space walk—I might have drifted a long way. And what the science of orbital mechanics tells us is that no two objects in orbit can have the same six numbers, except in the special case I just showed you, where I was inside the hollow arklet so that both of our centers of gravity could coincide. An arklet, or any other object, that is off to the port side of Izzy, or to starboard, or to the zenith or nadir side of it, or forward or aft of it, has different numbers by definition. It’s in a different orbit. And so it is going to drift.”

  He mentally reviewed his notes. Here he had intended to be more specific about the nature of that drift. If it’s in a higher orbit, it’ll fall behind. If it’s in a lower orbit, it’ll race ahead. If it’s off to one side or the other, it’ll converge, then diverge, on a ninety-three-minute cycle. Only if it’s directly forward, or directly aft, will it maintain the same relative position. But he thought maybe he could link that out to a different video, one with more graphics. Better to get to the point.

  “The moral of the story? In space, there is no such thing as formation flying. Physics will cause two nearby objects to drift closer together or farther away. If you want to preserve a formation, such as a swarm, you have only two options. Physically connect the arklets together, so that they become one object, or else use the thrusters to correct for the drift.”

  There was another option, which was to put them in single file, like a train in space, but it didn’t seem very swarmlike and so he left it out of the reckoning for now. Minutes after the video was posted, outraged YouTube commentators would be all over him, pointing out the error and attributing it to dishonesty, incompetence, and/or a conspiracy.

  His last task was to record a voice-over that would be played over footage of young Arkers training in huge industrial video arcades, thrown together for just that purpose in places like Houston and Baikonur. “It’s not difficult to learn this stuff—any video gamer can pick it up in a few minutes. Just ask these young Arkers, brought together from all over the world, who’ve been honing their arklet piloting skills using precision simulators. Most of the time, of course, the arklets will be flying themselves, on autopilot. But if and when it’s necessary for a human to take the controls, these young people will be ready for it.”