Читать книгу: «Seveneves»

Pioneers and Prospectors

“THE ICEMAN COMETH.”

“Ah.” Rhys sighed. “I was wondering which of us would be first to go there.” He pulled out, drifted away, and did a peel-and-knot on the condom so expertly that it created dark stirrings of jealousy in Dinah’s heart. But at least he didn’t let anything get loose in Dinah’s shop.

“This may have been your last delivery,” Dinah said. “Of ice, that is.”

“You’ve got your freezer?”

“Coming up on tomorrow’s launch from Kourou.”

“Any chance of getting them to send up a martini shaker with it?”

“We use plastic bags for that.”

“Well, I hope that my deliveries—of ice, that is—have contributed something to whatever the hell you’ve been doing.”

“Check this out,” she said. She’d already wrapped herself in a blanket, but now she prodded the wall with a toe and drifted over to her workstation. With a bit of clicking around she brought up a video. The opening shot was stark: a cube of ice in a black chamber, lit up by bright but cold LEDs.

“From Arjuna HQ, I presume?” Rhys, still naked, came up behind her and wrapped an arm around her waist. She liked to think of it as an affectionate gesture. In part it was. But she’d been in zero gee long enough to understand that he also just didn’t want to drift away while watching the movie.

“Yes.”

A bearded strawberry-blond man entered the frame carrying a sheet of corrugated cardboard—the lid of a pizza box.

“That’s Larz Hoedemaeker, I think—one of the guys I’ve been working with a lot.”

Larz angled the pizza lid slightly toward the camera. It was mostly covered by iridescent fingernail-sized objects, like silicon beetles. Hundreds of them.

“That’s a lot of Nats,” Rhys remarked.

“Well … the whole point is to make a swarm.”

“I understand. But it seems they’ve found a way to ramp up production.”

Larz folded the cardboard diagonally to make it into a crude trough and then angled it down toward the block of ice. The Nats avalanched down and tumbled onto it in a heap. Quite a few of them skittered off and tumbled onto the floor. Larz exited the frame for a moment, then returned, pushing a wheeled swivel chair. He arranged this behind the block of ice, then disappeared again, then came back carrying a clock that he had apparently just taken down from the wall of an office. He balanced this on the seat of the swivel chair, leaning back against its lumbar support, so that it was clearly visible in the frame of the video. Then he departed.

A few moments later the lights got much brighter. “Simulating solar radiation,” Dinah explained. “The Nats are solar powered, so the only way to test them is to have a light source as bright as the sun.”

The clock’s minute hand now began to sweep forward. “Time lapse?” Rhys asked.

“Yeah. This stuff happens slowly, as you’ve seen.”

The Nats that had scattered to the floor scurried around aimlessly for a bit, then seemed to find the block of ice, and scaled its vertical sides. “Pretty good adhesion, you’ll note,” Dinah said.

Meanwhile the heap of Nats on top spread out like a pat of butter softening on a pancake, distributing themselves in a somewhat random but basically even layer atop the ice block. A few of them appeared to sink into the ice. “Melting their way in?” Rhys asked.

“No. Uses too much energy—and wouldn’t work in zero gee. They are mechanically tunneling. See the piles forming?” She pointed to the top of the ice block, where mounds of white had begun to form around the exits of the tunnels. “That is spoil being carved out and ejected by the tunneling Nats.”

“You can’t make mounds in zero gee either,” Rhys pointed out.

“One thing at a time!” she said, elbowing him. “The other guys are working on it, see?” She used the cursor to point out another Nat that was making its way along the surface. It seized hold of some little ice grains from a mound, then backed away and headed toward the edge of the ice block.

“How’s it doing that?” Rhys asked.

“You know how when your hand is wet and you reach into the freezer and pick up an ice cube, it’ll stick to your skin? That’s all there is to it,” Dinah said. “And that is also how they crawl around on the ice without falling off.”

The minute hand on the clock began moving faster, and even the hour hand could be seen sweeping around now. The surface of the ice block became pitted and then began to sink toward the floor as material was removed. But at the same time, one edge of the block developed a bulge that grew into a cantilevered prong, like the horn on an anvil.

“What are they building?” Rhys asked.

“Doesn’t matter. This is just a proof of concept.”

The growth stopped, the clock dial slowed to normal time, another engineer walked in to snap some pictures of the result. Then the video cut away to a black screen.

“Interesting!” Rhys said.

She grabbed his hand before he could get away. “Hang on. Check out the superfast version.”

This started a moment later. It was just the same movie, shown ten times faster. So it only lasted for a few seconds. The Nats were invisible because of the speed of their movement—just a jittery gray fog that came and went in patches. This drew the eye to the block of ice. Shown at this speed, it looked less like a crystalline slab and more like an amoeba, sinking down at one end while smoothly projecting a pseudopod into space.

“One has to assume,” Rhys said, “that there’s a reason why Sean Probst is so very keen on making ice sit up and do tricks for him.”

“Yeah. But he’s not sharing it with me.”

“Is there any way,” he wondered, “of joining those Nats end to end?”

“Into a chain?”

“Yes. The Siwis are serviceable, but much more complicated than they need to be.”

“You have got chains on the brain. Yes, there’s a way. And you can join them side to side to make a sheet.”

“Uncle John is calling to me from beyond the grave, telling me to make something of his hobby.”

“Well, stay in my good graces,” she said, “and I’ll let you play with some.”

DAY 56

As of A+0.56, the Hub module around which the torus spun was no longer the aft-most part of Izzy. They called it H1 now. A larger hub, called H2, had been sent up on a heavy-lift booster from Cape Canaveral and mated with it.

H2 had originally been planned as the basis of a large space tourism operation. Rhys’s original mission, for which he’d been planning and training for two years, had been to get that up and running. It had a new purpose now, of course, but functionally it would look the same: H2, the big central module, with a new and larger torus rotating around it. That new torus, inevitably called T2, was going to be assembled in space from a kit of rigid and inflatable parts, some of which had been shipped up packed inside of H2, others to follow later on subsequent launches. For the time being, H2 had four fat spokes extending from it to terminate in stubs where other parts, forming the rim of the wheel, would be added later.

The Scouts by then had achieved their basic mission, which had been to employ the Integrated Truss Assembly as a backbone to support a tree of hollow pipes, each about fifty centimeters in diameter, with wide spots every ten meters or so. A human being, provided they were reasonably fit, and did not suffer from claustrophobia, and did not have too much stuff in their pockets, could move through a tube of that diameter, somewhat like a hamster scurrying through a plastic tube in a cage. The wide spots were there so that two people going opposite directions could pass each other. Spherical modules served as connectors and branch points. The tubes terminated in docking locations where spacecraft of various types could lock on to the space station and establish solid, airtight seals.

For it had been obvious from the beginning that docking sites were going to be, in the lingo of Pete Starling, “the scarce resource,” “the long pole,” “the critical path.” Building rockets, spacecraft, and space suits was no easy matter, but at least these things happened on the ground, where colossal resources could be thrown into beefing up production. An armada of space capsules hurled into orbit would have nowhere to go, however, unless they could dock somewhere. And the docking sites had to be built the hard way: on site, in orbit.

Docking was no joke, and required specific technology, but it was thoroughly understood and it had been done many times. The Chinese space program had standardized on the same system used by the Russians, so their spacecraft, like the Russians’, could dock at the ISS. So far so good. But the fact remained that every manned spacecraft launched into orbit needed to reach a specific destination within a couple of days’ time, before the occupants ran out of air, food, and water. The task of the Scouts, therefore, had been to vastly increase the number of docks in the quickest and cheapest possible way. Docks couldn’t be too close together, so the distances between them had to be spanned by hamster tubes. Bracketed to the outside surfaces of those tubes, and still being installed by fresh waves of Scouts, were runs of plumbing and wiring, and structural reinforcements tied into the adjacent trusses.

The initial tube tree, built between about A+0.29 and A+0.50 by Tekla and the other first-wave Scouts, sported half a dozen docking locations. These were spoken for immediately by the first wave of so-called Pioneer launches: three Soyuz spacecraft, two Shenzhous, and a space tourism capsule from the United States.

Encouraged by the success of the launch that had carried Bo and Rhys, the Russians had found ways to cram five or six passengers on each Soyuz.

The Shenzhou spacecraft was based on the Soyuz design, except larger, and updated in various ways. Like the Soyuz, it was meant to carry a crew of three—but this was based on the assumption that those three would want to return to Earth alive. Modified for one-way trips, each Shenzhou carried half a dozen. And the American tourist capsule brought a complement of seven astronauts.

So, all told, the first wave of Pioneers brought three dozen people to Izzy, more than doubling its population. They were obliged to live in their space capsules, which had their own toilets, CO₂ scrubbers, and heat rejection systems. This made for crowded conditions, but it was a step up from the Luks.

On A+0.56, when the H2 module came up on the giant Falcon Heavy rocket, Tekla and the other surviving Scouts spent a day pulling out all that had been stuffed inside of it and anchoring it temporarily to the outside of the module. They then moved into H2, turning it into a Scout dormitory and saying goodbye to their increasingly tatterdemalion Luks, which were deflated, patched, folded up, and stored for later use in emergencies.

About two-thirds of the Pioneers had previous experience doing EVAs or had been hastily trained over the last few weeks. There were not enough space suits to go around—these were being produced as fast as possible on the ground—but the existing ones could be shared. Work shifts were shortened from fifteen to twelve hours, and then to eight, so that fresh bodies could be rotated through the available suits two or three times a day. The spacewalkers divided their time between assembling the T2 torus and extending the tube trees to provide docking space for the next wave of launches.

The remaining Pioneers, the non-spacewalkers, devoted themselves to other activities inside the pressurized parts of the space station. Dinah found herself with two assistants: Bo, who had seemingly assigned herself to the task, and Larz Hoedemaeker—the guy from the video. Larz was a young Dutch man who had been pursuing a graduate degree in robotics at Delft when he had been recruited by Arjuna Expeditions. Dinah knew him as a prolific email correspondent, always willing to answer her questions or supply code patches on short notice. Owing to some lapse in communications, she hadn’t even known that he would be one of the passengers on the American tourist capsule that had arrived on Day 52 (for people were now dropping the A+ notation and simply referring to days by their numbers).

All she knew was that a large strawberry-blond man suddenly appeared in her shop, intent on hugging her. This was unusual. To put it mildly, the International Space Station, until now, had never been the kind of place for surprise visits.

Larz had a fistful of chocolate bars in one hand and a camera in the other, and all manner of stuff was spilling out of the pockets of his coverall: vials of morphine, antibiotics, reels of microchips on paper tape, disposable contact lenses, condoms, packets of dehydrated coffee, tubes of exotic lubricants, spare leads for mechanical pencils, bundles of zip ties. The policy now seemed to be that everyone being packed onto a ship first had to be so laden down with vitamins that they could hardly move.

Larz was an enjoyable person, and his first day on Izzy was pure fun for Dinah, who had not been able to have a face-to-face conversation with a colleague in a year. She showed him around the shop, such as it was, and let him drive robots around on the surface of Amalthea, and brought a few of her “Grimmed” robots in so that he could admire them. For, inspired by Rhys’s comment of a few weeks ago, Dinah had been putting her otherwise idle robots to work making armor for other robots. The orderly way to do it would have been to bring pieces of the asteroid back to her little zero-gee smelter and produce nice little ingots of pure steel, then weld them onto the frames of the Grabbs. But this was making things too complicated. Amalthea was already made out of perfectly sound material. Maybe it was not structural-grade steel, but it was good enough to serve as radiation shielding. So she had just been slicing pieces of it off, leaving them in their original rough shape, and armoring Grabbs with overlapping plates of the stuff. They looked like walking asteroids now.

“It is an art project,” Larz said. For a moment she thought he was trying to insult her. Because she had met a few engineers in her day who never would have combined art and engineering. But his face was happy and guileless, and it was clear that he was paying her a compliment.

Once she’d gotten a bit used to him, she broached the subject that had been on her mind now for several weeks: Why ice? Given that they had direct access to a giant chunk of iron, why was Arjuna now putting all of its efforts into working with a material that for all practical purposes didn’t exist on Izzy?

“Some things are not always explained to me,” Larz said, “but you know that we have talked for some time about going after a comet core.”

“Sure,” Dinah said. “We’ve talked about it. But those things are huge. What are we going to do with a few gigatons of water?”

Larz just blinked and looked mildly uneasy.

“It would take forever to move something that big!” Dinah said. “It is, like, a tenor twenty-year project! We don’t have that much time.”

“Under the old conditions, yes.”

“What do you mean, the old conditions?”

“Back in the day—before the Agent—when we talked about moving comets, we were talking about sending up a big mirror. Focusing the sun’s light on the comet core, boiling off a little water, pushing it slowly to a new trajectory. Yes. That would take a long time. Like pushing a bowling ball with a feather.”

“And what about that has changed?” Dinah asked. “Physics is physics.”

“Yes,” Larz said, “and some physics is nuclear physics.”

“We’re going to use nukes? I thought that was—Jesus. I don’t even …”

“You don’t appreciate how much things have changed down there,” Larz said.

“I guess not!”

“The Arkitects came out and said, ‘Listen, there is no way of making this work with solar cells. We can’t make enough of them, fast enough, for thousands of arklets. They are big and cumbersome.’”

“I’d been wondering about that.”

“We have to use nukes, is what they said.”

“RTGs?”

Radioisotope thermoelectric generators were the power units used to run most space probes. At the heart of each was a puck of an isotope so radioactive that it remained hot for decades. Energy could be extracted from that heat in various ways.

“Those are not nearly powerful enough,” Larz said.

LARZ GOT MESSAGES FROM THE GROUND IN THE FORM OF ENCRYPTED email, a spate of capital letters in groups of five that looked like something straight out of an Enigma message. In the big nylon wallet that, for Larz, passed as a briefcase was a stack of pages. On each of these was printed a different grid of random capital letters. About half an hour of laborious pencil-and-paper work went into decrypting each message. Dinah couldn’t believe her eyes. People used crypto all the time to send email, of course, and it was standard practice for all Arjuna Expeditions email to be enciphered. But apparently that was no longer good enough for Sean Probst. Dinah got used to seeing Larz toiling over these sheets. He wrote a little Python script to make it easier, but he still wrote the messages out by hand.

One day, two weeks after he’d arrived, he decrypted a message with some surprising news. The boss was coming. As in, Sean Probst, the founder and CEO of Arjuna Expeditions.

“How can that even happen?” Dinah asked. “How can anyone just come up to Izzy? Don’t you need a launch vehicle? A spacecraft? A place to dock it? Permission?!”

These were largely rhetorical questions. Sean had made seven billion dollars from an Internet startup before throwing his energies into asteroid mining. Along the way he’d sunk a billion or two into other private space startups.

“He’s coming up alone,” Larz said, “in a Drop Top.”

It took Dinah a moment, and a quick Google search, to access the memory. Also referred to as “the Convertible,” the Drop Top was one of the more creative recent approaches to space tourism. It was based on the idea that what tourists really wanted to experience was the direct view of the Earth, the stars, and (until it had ceased to exist) the moon. Conventional space capsules had tiny windows. What you really wanted to do was stick your head into a transparent bubble so that you could enjoy a clear view out in all directions. In other words, you wanted to be in a space suit, basically floating free in space. The Drop Top was a small, simple capsule, capable of carrying four astronauts, dressed in custom-made space suits with bubble helmets. During the ascent through the atmosphere, and the reentry, they were protected by a sturdy aeroshell. But while they were orbiting the Earth, the shell retracted, like the roof of a convertible, exposing them completely to space, and even giving them some freedom to spacewalk.

“I don’t think a Drop Top can reach an orbit this high, can it?” Dinah asked.

“Sean’s coming up alone. It is some kind of special one-passenger model—the extra mass is being used for propellant.”

“And then what? He just goes to an airlock and knocks on the door?”

“Basically, yes,” Larz said. “What will they do? Tell him to go away?”

DAY 68

“This whole thing is bullshit,” said Sean Probst as soon as he got his helmet off.

Dinah smiled. It was not that she was happy about the bullshit. When it came to preserving the human race and the genetic heritage of the Earth from destruction, any whiff of bullshit was bad. But she did feel a certain sense of relief. In the back of her mind she had been quietly tallying up the BS for weeks now. No one else here would speak of it, and most of them seemed smarter, better informed than she was.

She knew Sean Probst by his reputation, by his signature on her paychecks, and by the emails he sent her at three o’clock in the morning of whatever time zone his private jet had most recently taken him to. Sean yielded to no one in his knowledge of all things space related. When he walked into a space station and called bullshit, things were about to become entertaining.

One of the few appealing things about him was that he had figured out that his personality was a problem and, in classic “get it done” style, had hired a coach to make him less of an asshole. She could see that working in his face.

“Not your part of it—that’s awesome,” he admitted.

“I figured you would have said something earlier if that were not the case,” Dinah said.

Sean nodded. Done.

His arrival at the space station had been unconventional, and roundabout. There was no docking station to accommodate the Drop Top. There couldn’t possibly be, since the Drop Top didn’t even have a port or an airlock. So there’d been no way to attach it to Izzy. He had brought the little convertible in under manual control, tapping the thrusters one at a time, spitting bullets of spent propellant into space, then pausing for one, five, or ten minutes to ponder the consequences. Space nerd that he was, he knew perfectly well that orbital mechanics did not obey the rules of earthbound physics. He had enough humility, and enough spare oxygen, to take it slow. Eventually he had drifted close enough to Amalthea that a three-Siwi train with a Grabb on its head had been able to reach out and grapple a fitting on the edge of his cockpit. He had then ejected himself from the vehicle, floating free in space, and gone on a little tour of inspection, firing off occasional messages to Dinah so that she could know where he was. Since there was no direct radio connection, these had to be relayed through a server in Seattle.

He was in a tubesuit: a tourist product that in some ways was less capable, in others more so, than the government-issue ones used by cosmonauts and astronauts. It had no legs at all, since legs were pretty useless in space. It looked like a test tube with a pair of arms and a bubble-shaped dome on the top. The arms had shoulder and elbow joints, but no hands as such. Gloves were notoriously the most troublesome parts of space suits. Instead, the tubesuit’s arms terminated in rounded-off stumps. Projecting from each of these was a skeletal hand consisting of a thumb and three fingers, actuated by steel cables that ran through airtight fittings into the arm-stumps. The occupant could slip his hand into a glovelike contraption inside the stump that would pull on the metal tendons as he moved his fingers, thereby actuating the external digits and enabling him to grab things and perform a few simple operations. There was nothing about it that couldn’t have been built by a tinkerer in an inventor’s lab in 1890, or 1690 for that matter. People who had used them reported that they worked surprisingly well—better in some ways than conventional space suit gloves, which were stiff and fatigued the hands.

There was plenty of extra room inside the stumps, and so when not using the clawlike hands he could pull his fingers free of the internal glove and let them rest on internal touchpads and joysticks where he could type and swipe to his heart’s content. The suit had some tiny thrusters that enabled the user to “fly” it around. Sean had put these to work at some length, wandering around the outside of Izzy and inspecting the work of the robots, the modifications made to the truss, and other curiosities.

Finally he had found his way to an airlock at the aft end of H2, where Dinah had let him in, and he had blurted out his opinion.

He looked like any nondescript thirty-eight-year-old nerd at a graduate physics seminar or a sci-fi convention, with stringy dishwater-blond hair stuck to his head by sweat, and a few days’ darker stubble. In his official photos he wore contacts, but today he wore thick-lensed eyeglasses. He pulled one arm, then the other, out of the suit and then pushed himself up and out through the big opening at its top where the head-dome had been attached.

“I’ve been having trouble seeing the long-term sustainability angle,” Dinah admitted. For she was not above dangling bait.

“Ya think?!” he shouted. “Has anyone done even the most basic mass balance calculation on this Cloud Ark concept?” Sean was from New Jersey.

She wasn’t sure what he meant, so she stalled for time. “People have been pretty distracted. I wouldn’t be the first to know.”

“They wouldn’t tell you!” he shouted. “Because you would see right away that it is bullshit!”

“What is?” Ivy asked, floating toward them with an interested look on her face. “And who the hell are you?”

Before Sean could explain who the hell he was, he was distracted, to put it mildly, by the appearance of a six-foot-tall Amazon with a shaved head and prominent facial scars, headed for him across H2 as if she had been launched out of a cannon. Tekla drove her shoulder into Sean’s midsection, slamming him back against a bulkhead. A moment later she was on him. She grabbed an outstretched arm and put Sean into a joint lock that looked pretty much inescapable.

By now Dinah had spent enough time with Tekla to know that she was a practitioner of Sambo, a Soviet combat martial art with many similarities to jujitsu. Out of idle curiosity, Dinah had watched a few YouTube videos featuring Sambo practitioners in action. But she had never imagined, until now, that it could be done in zero gravity.

Sean had made his entry through H2 because it had a useful assortment of airlocks and docking ports on its aft end. But, unbeknownst to him, H2 had been doing double duty as the dormitory where the surviving Scouts lived. His arrival had awoken Tekla, who was off shift at the moment and had been sleeping in her bag.

Dinah tried to imagine what this encounter must have looked like from Tekla’s point of view. Sean’s arrival was unannounced. Dinah herself hadn’t really known when, or whether, he was going to arrive until the Drop Top had swum into view outside her little window. So, from Tekla’s point of view, this guy was an intruder. And when she’d heard Ivy say “Who the hell are you?” she had realized that his presence on Izzy was completely unauthorized.

“Oh, this is awkward,” Dinah said.

“Tap! Tap!” Sean kept saying. He was slapping Tekla’s leg with his free hand.

“Commander, would you like me to restrain him?” Tekla asked. “What are your orders?”

“He’s not dangerous,” Dinah put in.

“Let him go, Tekla,” Ivy said.

Somewhat reluctantly, Tekla relaxed her grip and allowed Sean to float free. He drifted away from her, sizing her up with a certain degree of bewilderment.

“Sean,” Dinah said, “you’ve already made Tekla’s acquaintance. I would like you to meet Ivy Xiao, commander of this installation. Ivy, say hello to Sean Probst.”

“Hello, Sean Probst,” Ivy said, then turned to look at Dinah. “Did you know he was coming?”

“I had heard rumors,” Dinah said. “But I did not think them firm enough to distract you by repeating them. I am sorry.”

Ivy looked at Sean long enough to make him uncomfortable. Tekla, hovering almost within reach, did much to help supply the hostile atmosphere that Dinah suspected Ivy was reaching for.

“The closest analogy in the law for what I am here is the captain of a ship,” Ivy said. “Do you know the etiquette, Sean, for coming aboard a ship?”

Sean calculated.

“Commander Xiao,” he said, “I humbly and respectfully request permission to come aboard your ship.”

“Permission granted,” she said. “And welcome aboard.”

“Thanks.”

“But!”

“Yes?”

“If anyone asks, you’ll please tell them a little white lie, which is that you requested permission first, and then came aboard.”

“I’m happy to do that,” he said.

“Later on we’ll evolve some sort of common law, I guess. A constitution for this thing.”

“People are working on that, actually,” Sean offered.

“That’s nice. But right now we have nothing of the sort and so we have to be mindful.”

“It is so noted,” Sean said.

“Now,” Ivy said, “you were saying something about bullshit when I interrupted.”

“Commander Xiao,” Sean said, “I have the utmost respect for your past accomplishments and for the work you have been doing.”

“Do you hear a but coming?” Ivy asked Dinah. “I hear a but coming.”

Sean stopped.

“Go on,” Ivy said. For at the end of the day, to go on was what Sean wanted, so they might as well get it over with.

HE WORKED IT OUT FROM FIRST PRINCIPLES ON THE WHITEBOARD IN the Banana. Beginning with the Tsiolkovskii equation, a simple exponential, he developed some simple estimates, which he then developed into an ironclad proof, that the Cloud Ark was bullshit.

Or at least that it had been bullshit until he, Sean Probst, had shown up to address the problems he had noticed. Problems that could only be handled by him personally.

It occurred to Dinah to ask herself whether Sean was really rich anymore.

Rich people no longer kept their wealth in gold. Sean’s wealth was in stock—mostly stock in his own companies. She hadn’t been following the stock market since the Crater Lake announcement, but she’d heard that it had not so much crashed as basically ceased to exist. The whole concept of owning stock didn’t really mean much anymore, at least if you thought of it as a store of value.

But legal structures, police, government agencies, and so on still existed and still enforced the law. The law stated that Sean, by virtue of majority ownership of Arjuna Expeditions, still controlled it. And through overlapping relationships with other space entrepreneurs, he still had enough pull to get himself launched to Izzy. So that counted as wealth of a sort.

Having settled that in her mind, she focused her attention back on what Sean was saying.

“Cloud Ark as distributed swarm: fine. I get it. Sign me up. Much safer than putting all our eggs in one basket. What makes it safer? The arklets can maneuver out of the way of incoming rocks. Other advantages? They can pair up to make a bolo, and spin around each other to make simulated gravity. Keeps people healthier and happier. How do they do this? By flying toward each other and grappling their tethers together. What happens when they want to break up the bolo, and go solo? They decouple the tethers and go flying off in opposite directions, unless they use their engines to kill that centrifugal motion. What do all of these activities have in common?”

They’d gotten used to Sean’s habit of asking, then answering his own questions, so were caught off guard now that he actually seemed to be expecting an answer.

Dinah and Ivy had been joined by Konrad Barth, the astronomer; Larz Hoedemaeker; and Zeke Petersen. The latter finally rose to the bait.

“Use of the thrusters,” he said.

Sean nodded. “And what happens when we are using the thrusters?”

Dinah had an advantage, since she already knew that Sean was concerned about mass balance. “We’re dumping mass. In the form of used propellant.”

“We’re dumping mass,” Sean said, nodding. “As soon as the Cloud Ark runs out of propellant, it loses the ability to do all of the things that make it a viable architecture for long-term survival. It becomes a big sitting duck.”

He let them roll that around in their heads for a bit, then went on: “Mind you, almost everything else that we do up here can be done with minimal effect on mass balance. We can recycle our urine to make drinking water and our poo to make fertilizer. Very few of our activities involve just releasing mass into space in a way that we can’t get it back. This is the exception. I have been ranting and raving about this ever since the idea of the Cloud Ark was announced. So far all I get in return, from the powers that be, are vague answers and hand-wavy happy talk.”

Ivy and Dinah looked at each other in a way that foretold a one-on-one, after-meeting tequila session.

So, Dinah thought, Ivy had been wondering about this too, in the back of her mind. Worrying about it. Trying to read the tea leaves during those teleconferences down to the ground.

It was something to do with Pete Starling, she now saw. Which meant that it was somehow related to J.B.F.

Zeke was one of those open-faced, basically optimistic team players one saw frequently in the junior officer ranks of the military. “This is so obvious, in a way,” he pointed out. “They have to have thought of this.” Which was Zeke’s way of saying I’m sure that this is all being handled by people above our pay grade.

“You would think,” Sean said, nodding.

Konrad shifted in his chair uneasily and thrust his bearded face into his hand. Unlike Zeke, he was not the sort to place the sunniest interpretation on the problem.

“If the world were run by scientists, engineers,” Sean said, “then this would be a no-brainer. We have to go get more mass. Stockpile it so we don’t run out.”

“It’s got to be water. You’re talking about a comet core,” Dinah said.

“It’s got to be water,” Sean agreed. “You can’t make rocket fuel out of nickel. But with water we can make hydrogen peroxide—a fine thruster propellant—or we can split it into hydrogen and oxygen to run big engines.”

“I’m waiting for the other shoe to drop in what you just said,” Ivy muttered. Then she spoke up more clearly: “But the world isn’t run by scientists and engineers—is that where you’re going with this?”

Sean turned his hands palm up and shrugged theatrically. “I’m not a people person. People keep telling me this. Some who are people persons might be focusing on that angle.”

“The people angle,” Konrad said, just clarifying.

“Yeah. The seven billion people angle. Seven billion who need to be kept happy, and docile, until the end. How do you do that? What’s the best way to calm down a scared kid, get them to go back to sleep? Tell them a story. Some shit about Jesus or whatever.”

Zeke winced. Konrad rolled his eyes, then glanced at the ceiling and pretended he hadn’t heard this.

The idea Sean was playing with here was so monstrous in a way that it was almost inconceivable: that everything they were doing up here was a lullaby for the seven billion down below. That it could not actually work. That they were just putting on a show of getting ready. That the people of the Cloud Ark would live only a few weeks longer than the ones left behind.

As such, Ivy and Dinah and Konrad and Zeke ought to have been freaking out at this point.

But none of them—not even Zeke—reacted very much.

“You’ve all thought it too,” Sean said. “Even an Asp-hole like me can see it in your faces.”

“Okay, maybe we’ve all thought it,” Dinah admitted. “How could you not think it? But, Sean, what you might not have seen, being based on the ground, is how serious everyone up here is about making this work. If it were just a Potemkin village, we’d be seeing different stuff.”

Sean held his hands up, palms out, placating her. “Can we just agree that there might be a range of views down on the ground? And that some people, perhaps highly placed, see its primary function as an opiate of the masses? Like the video you pop into your car’s DVD player to keep the kids quiet during a long drive.”

“People like that are not going to be our friends when it comes to getting the resources we need,” Ivy said.

“Their strategy is always going to seem a little off-kilter, a little beside the point. Opaque. Frustrating.”

They were definitely talking about Pete Starling.

Sean continued. “To the extent that such people control launch sites and policy, we have a problem. Fortunately, they don’t control everything.”

They were now talking about Sean Probst, and his loose circle of billionaire friends who knew how to make rockets.

“There’s a lot about this Cloud Ark thing that I, and my associates, don’t know yet. We can’t sit around waiting for perfect knowledge. We have to act immediately on long-lead-time work that addresses what we do know. And what we do know is that we need to bring water to the Cloud Ark. Physics and politics conspire to make it difficult to bring it up from the ground. Fortunately, I own an asteroid mining company. We have already identified some comet cores in easy-to-reach orbits. We’re narrowing down the list. And we’re preparing an expedition.”

Konrad well understood the timing of such missions. “How long, Sean?”

“Two years,” Sean said.

“Well,” Ivy said, “I guess you’d better get on it, then. How can we help?”

“Give me all of your robots,” Sean said. He turned to look at Dinah.

“SINCE WE HAVE DECLARED OPEN SEASON ON BULLSHIT …” DINAH began as soon as she had gotten Sean Probst alone in her shop.

Sean held both of his hands up like a fugitive surrendering to the FBI. “Where would you like to begin?”

“You said that you have identified some comets. That you were narrowing down the list. That’s crap. You wouldn’t have come up here without a specific plan.”

“We’re going after Greg’s Skeleton.”

“What?”

“Comet Grigg-Skjellerup. Sorry. Somebody’s offspring called it Greg’s Skeleton and the name stuck.” Sean always referred to children as offspring.

She’d heard of it. “How big is that?”

“Two and a half, three kilometers.”

“That’s a lot of arklet fuel.”

Sean nodded. He crossed his arms over his body and looked around the shop.

“Hard to move something that big.”

Still no answer.

“You’re going to jam a nuke into it and turn it into a rocket, aren’t you?”

He raised his eyebrows briefly. Since this was the only plausible way of moving something that huge, he didn’t consider it worthy of an extended answer.

“We got really lucky on the timing,” he remarked.

“You’re going to fly a radioactive ice ball the size of the Death Star back here just as the shit is hitting the fan—then what?”

“Dinah, I need to share something with you in confidence.”

“Well, it’s about fucking time is all I can say.”

DAY 73

Doob had almost been to space once, about ten years ago. An acquaintance of his who had made a lot of money in hedge funds had dropped twenty-five million dollars on a twelve-day trip to the International Space Station aboard a Soyuz capsule. It was traditional for the customer to designate a backup—a sort of understudy—who would take his place in the event of some illness or mishap. Since the backup might be swapped in at any time up to shortly before launch, they had to go through all the same training as the customer. And that was really the point, as far as the hedge fund man was concerned. An introvert, he needed someone who could act as a connection to the general public and put an appealing face on the whole thing. So he had selected Doc Dubois as his understudy. They’d set up a website and a blog, and arranged for photographers to follow Doob’s progress through the training program, with occasional glimpses of the hedge fund man in the background. In effect, Doob had acted as a publicity decoy. No one made any bones about this. Doob had been more than happy to do it. The training had been great fun, the hedge fund man had been generous in his spending on the website, and Doob had been able to produce a lot of good video explaining fun facts about spaceflight.

And there had even been the small chance that he might go. A week before the scheduled launch, he had flown to Baikonur, bringing his wife and kids with him, video crew in tow. They had watched in a certain amount of amazement as the launch vehicle, a fantailed Soyuz-FG, had been towed horizontally across the steppe on a special train, complete with smoke-belching locomotive, to the launch pad. And this really was little more than a pad, a concrete slab on the almost lunar surface of the Kazakh steppe with a few pieces of apparatus around it to hoist the rocket up off the train and pump fluids into it. The contrast with the NASA way of doing things was stark to the point of being somewhat hilarious. Doob’s youngest son, Henry, eleven years old at the time, had failed to pay attention to the elevation of the mighty rocket to its vertical position because he was distracted by the sight of a couple of stray dogs copulating a hundred meters away from ground zero. The launch bunker, shockingly close to the pad, had a little vegetable patch out in front of it where the technicians were growing cucumbers and tomatoes; they explained that the concrete wall soaked up sunlight during the day and helped keep the vegetables warm at night.

Three days before launch, the hedge fund man had been nipped by a stray dog while rehearsing a launch pad escape sequence, and everything had been thrown into disarray as the dog was chased across the steppe by militiamen in wheeled vehicles, locals on horseback, and a helicopter gunship. After they had run it to ground they had shipped it off to a veterinary lab to be checked for rabies. Only three hours before launch, word had come back that the dog was clean. Doob’s name had been struck from the manifest and replaced by that of the hedge fund manager. Both relieved and disappointed, Doob had stood on terra firma, very close to the launch pad. Tavistock Prowse had come out to cover the launch. He had come equipped with all kinds of electronic gadgets that had seemed cool at the time. He had stood there on the steppe, facing Doob and the rocket, aiming a video camera at him and catching his narration as the giant vehicle had fired up its engines and hurled itself into the sky.

More than anything else, that image had made Dr. Harris into Doc Dubois and launched his career. It had also led, within days, to divorce proceedings initiated by his wife. She had a number of complaints about his performance as a husband, many of long standing, some that she could barely articulate. But somehow all of them had been summed up and crystallized by the fact that, after largely ignoring his responsibilities as a husband and father for several weeks while training for this launch in Russia, he had spent the actual moment of launch not gathered in a safe place with his children but outside, dangerously close to the rocket, with his bro Tav, ingratiating himself to millions of followers with excited and hilarious commentary.

One way or another, Doob had been paying for it ever since. Partly in the negative sense of suffering just penalties for his sins but partly in the more positive sense of spending time with his kids when he could. And this had become more difficult as they had graduated from school and gone out into the world. He was making a particular effort to do it now that they were all under a death sentence.

On A+0.73, Doob flew into Seattle, rented an SUV, and drove to the campus of the University of Washington. Along the way he stopped at a couple of outdoor stores to pick up some camping equipment. This was now expensive. People had begun hoarding that sort of thing in anticipation of a collapse of civilization. But only a few people. Most understood that there was little point in taking to the hills when the Hard Rain began. Freeze-dried food and backpacking stoves were difficult to come by, but down sleeping bags and fancy tents were still in stock.

Henry was now a junior in the computer science department, living with some of his friends near the campus in a rental house, a classic Seattle down-at-heels Craftsman bungalow half digested by blackberries and English ivy.

In a certain way it made no sense anymore to speak of anyone as being a student at a particular stage in a degree program. And yet people went on thinking this way, kind of in the way that someone who has just been diagnosed with a terminal illness will go on getting up and going to work every morning, not so much out of habit as because the knowledge of impending doom makes them wish to assert an identity.

He was tempted to park the SUV illegally, since, according to his calculations, the authorities were not likely to catch up with him and demand payment of the parking ticket before the end of the world, but it seemed that most of the people of Seattle were still obeying the rules and so he did likewise.

He found Henry, all four of his housemates, and five other students all crammed into the ground floor of the bungalow, keeping it warm in the January chill with their body heat and the warmth emanating from a rat’s nest of PCs, laptops, and routers. A quick census of empty pizza boxes suggested that they had been working all night.

“I’ll explain it to you while we drive” had been Henry’s promise to his dad when Doob had asked him on the phone last night what he was doing. This morning, other than getting up from his La-Z-Boy to give his dad a hug and tell him “I love you,” he didn’t have much more to say.

Every parent of a teenager gets used to it: the moment in a child’s life when he or she decides that certain facts are just too much trouble to explain to Mom or Dad. The parents can’t, and needn’t, know every last little thing. They just have to accept this, be content with what they can glean on their own, and move on. Henry, of course, had passed through that veil some years ago. Doob had swallowed his pride and accepted it as every parent must. It was part of growing up. But back in those days the subject matter had been fundamentally uninteresting: the size of Henry’s collection of Magic: The Gathering cards, the weight lifting program assigned him by his football coach, and who had a crush on whom at school. It was easy for Doob to pretend he didn’t care about that stuff.

What he was seeing over the shoulders of the students in this room looked a good deal more interesting. And that, in a way, hurt.

All of them, of course, knew that Henry was the son of the famous Doc Dubois. While trying to play it cool, they all sought a chance to shake his hand and say hi. Doob chewed the fat with them while his eyes strayed to the stuff they had blue-taped to the walls of the bungalow: printouts of CAD drawings, schedule grids, Gantt charts, maps. He was obviously looking at some sort of engineering project in the works, but he couldn’t make out what, exactly. On the kitchen table a MakerBot was producing a small plastic part, watched intently by a young woman who was talking on her phone in a mix of English and Mandarin.

Conversation was interrupted by the beep-beep-beep of a backup alarm, loud and growing louder. Someone pulled the front door open, letting in a wash of wet, cool Pacific air, to reveal a Ryder box truck backing up onto the lawn, heading straight for the front door. Some unkillable instinct in Doob’s head made him glance disapprovingly at the muddy ruts it was leaving in the lawn, made him issue a little tut-tut-tut at these irresponsible youth for damaging the grass—grass that in two years would be a thin smear of carbon black over a lifeless cake of hardened clay, presuming it didn’t suffer a direct hit and become part of a huge glass-lined crater.

The truck didn’t stop soon enough and wrecked a wooden banister beside the front steps.

Everyone laughed. The laughter had a curious tone, a mixture of childish delight with something darker, expectant of much worse to come.

These kids were really adapting better than he was.

He had no idea what was going on, but it seemed to involve throwing everything into the back of the box truck. He stood around for a while with his hands in his pockets, since he didn’t know which stuff was going and which was staying. But when they threw in the sofa it became clear they were abandoning the house. He began helping. After a certain point the box truck filled up. Then they began pulling things out of it and putting them back in in a more orderly style. Doob finally hit his stride, stepping into the role of wily old man with excellent packing skills and pointing out ways to use the space more efficiently.

Eventually someone went and got another box truck. Apparently the rental agency was letting them take them for free. Some day laborers wandered down the street from a home improvement center and helped pack. The home improvement market had gone bust. Doob saw traces of Amelia in their faces and wondered how they had first heard the news.

Six of the kids packed themselves and their computers, clothes, and as many tools as they owned or could borrow into the SUV that Doob had rented at the airport. They roped a couple of bicycles and some camping gear to the luggage rack. Doob had no idea where they were going, or why, but they seemed to be planning to construct a new civilization out of blue tarps and zip ties.

They ended up in a caravan of twenty vehicles, headed east out of town at about two in the afternoon. At this time of the year, at Seattle’s high latitude, that gave them about two hours of remaining daylight.

Most of the kids fell asleep immediately. Henry, riding shotgun, made a touching effort to stay awake and then fell into slumber. Henry was a sweet kid and Doob knew that when he woke up he would apologize. But Henry wasn’t a parent, and he didn’t understand that when you were, almost nothing was more satisfying than seeing your kid sleep.

So, feeling as content as it was possible to be under the circumstances, Doob drove into the darkling mountains with his SUV-load of slumbering passengers. The caravan gradually dissolved into the general stream of traffic. Most of the passenger cars peeled off at the suburban exits, before the road began to gain serious altitude. Doob wondered, as he always did, what the hell they were doing: Continuing to go to jobs and school, just to fill the days before the end? But it was none of his business.

Beyond Issaquah, any vehicle still on the interstate was probably headed for the high cold desert on the east side of the mountains. A few people were still interested in skiing—skiing!—but those cars were easily identified. Most of the other vehicles fit the general description of those that had been a part of their original caravan from the university: heavy-laden box trucks, SUVs and pickups with provisions and camping gear.

Doob realized that he had somehow become a sort of Okie.

Except that the Okies had at least known where they were going.

The eternal Seattle drizzle turned into alternating belts of mist and cold rain, forcing him to keep one hand busy on the wiper control. The raindrops became cloudy with ice as he gained altitude, and then turned into snow. The roadway was still clear, but the shoulders became fuzzy with slush that gradually encroached on the traffic lanes. The speed of travel dropped to forty, thirty, twenty miles an hour, and the road ahead congealed into a slurry of taillights as lowering steel-gray clouds clamped down on the remaining traces of daylight.

A few semi-articulated rigs were laboring up the approach to the pass in the slow lane. Some of these were just conventional boxy trucks and so there was no guessing what might be in them, but Doob thought he was picking out an unusual amount of weird industrial traffic: tankers carrying cryogenic liquids, flatbeds with bundles of tubing and structural steel.

The clouds flashed, bright enough to make some of the sleeping students flinch and stir in the backseat. Out of habit, Doob began counting zero Mississippi one Mississippi two … and when he reached something like nine or ten he felt, as much as heard, the sonic boom. As a child he’d have assumed it was a lightning bolt. Now he interpreted all such events as incoming chunks of moon shrapnel. This one had passed within about three kilometers. A secondary boom, several seconds later, suggested that it had hit the ground, as opposed to just breaking up in the atmosphere as most of them did. So it had been a relatively large piece.

It had been a day or two since Doob had checked the site where his grad students had been tallying observed bolides vs. the predictions of their model. He didn’t check it very often because, after some jitter in the first few weeks, the model had been refined to the point where it tracked observations to within a reasonable statistical range. This, of course, was good news for the model and bad news for the human race, since it meant that they were still on track for the White Sky to happen, and the Hard Rain to begin, in another twenty-one or twenty-two months. If memory served, strikes like the one he had just observed were probably happening about twenty times a day worldwide. So it was mildly remarkable that he’d been close to one, but nothing to write home about.

A few minutes later the taillights ahead of him flared as people applied their brakes. After inching along for a short distance traffic came to a complete stop. This woke up some of the students, who remarked on it sleepily. After ten minutes had passed without movement, Henry climbed out, stood up on the SUV’s running board, and began loosening ropes holding a bicycle in place on the roof.

Doob sat warm and safe in the driver’s seat and watched his son pedal off between the lanes of stopped traffic with precisely the same heartsick feeling as when the boy had gone off on his first solo bicycle ride in the streets of Pasadena.

He was back all of three minutes later. “A rig jackknifed just before the top of the pass,” he said. “An oversized load, a piece of a gantry, I think.”

Gantry. There was a word that activated deep memories in Doob’s brain. Only used in connection with launch pads, only spoken by the likes of Walter Cronkite and Frank Reynolds in the deep nicotine-cured anchorman tonalities of the Apollo days.

Nothing was happening, so they pulled their winter coats out of the back, bundled up, and hiked up the road to see. A lot of people were doing this. This struck Doob as unusual. The normal behavior was to wait in the car, thumb the iPhone, listen to a book on tape, and wait for the authorities to come and deal with it.

The stranded truck was only about half a mile ahead of them. It looked to have gone into a spectacular skid. The colossal weight of the gantry—a welded steel truss looking like a section of a railway trestle—had swung the rear end of the truck forward and sideways, sweeping across all lanes of traffic and finally grinding to a stop by flopping over onto its side and then destroying about a hundred yards of guardrail. Behind it a few cars had spun out as their drivers had stomped the brakes, and a few people were dealing with the aftermath of minor rear-end fender benders, but no one seemed to have gotten seriously injured.

The pedestrian traffic toward the crash had been considerable, and yet Doob saw few of the sorts of people he would classify as gawkers or rubberneckers. Where were they all going? As he and Henry and the other students drew closer he saw cars moving around, headlights sweeping across the wreck to better illuminate it, and then he saw a stream of people squeezing through the gap to the other side, or clambering through the space between the tractor and the trailer. Self-appointed safety wardens had stationed themselves at critical locations to focus the white beams of their LED flashlights on trip hazards and useful handholds. Doob and the others crowded through those gaps and then broke free to the far side of the wreck. The view here was worth a look. The wet interstate, completely empty of traffic, stretched away from them. A ski area, lit up for night use, spread up the mountainside to their right. In the distance maybe ten, twenty miles away, a streaky patch of mountainside was flickering a lambent orange through intervening veils of snow and mist: the impact site of the bolide. Doob saw now how it had all happened. The meteor had passed overhead. To him it had just been a flash above the clouds, but to the people cresting the pass at the same moment it must have been visible as it streaked into the ground and plowed up a mile-long stretch of forest. Cars must have faltered and strayed out of their lanes. The driver of the truck had been forced to apply his brakes and the tires of the trailer had broken loose from the slushy pavement.

The number of people on this side of the wreck must have been well over a hundred.

Twenty minutes later, there were enough of them to flip the rig back up onto its wheels. Like a work crew of Egyptian slaves moving a great block of stone, all of these people in their parkas and their microfiber gloves and snow pants just got under the thing and started lifting it. Towing straps had been fetched from toolboxes and anchored to the other side of it, and run to the trailer hitches and the bumpers of several pickup trucks that had four-wheeled their way to the scene, and they pulled while the humans pushed, and with surprising ease the whole thing came up, balanced for a moment on half of its wheels—the only sound now being the skidding of pickup tires as the drivers burned rubber—and then dropped into place. A huge uproar of people shouted Whoo! as much in relief as in exultation. Doob exchanged thumping, mittened high fives with twenty people he’d never met before and would never see again.

Getting the truck pointed in the right direction again, and back on its way down the interstate, was a more tedious operation that would likely span another couple of hours. But within a short time they were at least able to open one lane. By then, people with four-wheel-drive vehicles had already begun to cut across the median strip and claim lanes on the wrong side of the interstate, which was sparsely trafficked by veering cars holding their horn buttons down in long Dopplered howls of protest.

Another slowdown caught them an hour later when they entered a low plume of thick smoke drifting across the highway and bringing visibility down to almost nothing. Galaxies of red and blue flashing lights emerged from the murk and then receded: places where emergency vehicles had clustered to stage firefighting efforts, or to aid locals affected by the strike. At one place, sitting in the middle of the road, festive with road flares, was a rock the size of a car, which had struck the pavement hard enough to pierce it and lever up thick shards bristling with snapped rebar. Not the meteorite itself, but ejecta: shrapnel hurled out from the impact site.

There was another delay, this one purely for gawking, at the place where the interstate crossed the Columbia River, almost a mile wide, at Vantage. Something was going on down below the bridge, on the eastern bank of the river where the low span angled up away from the water to let big barges pass beneath it. Blinding lights had been elevated on poles, creating a mottled spill of daylight where something huge and cylindrical was being winched up off a barge.

With all of those complications it was well after midnight when they reached the town of Moses Lake and turned off the interstate to follow almost all of its traffic in the direction of the Grant County International Airport.

That was its official name. When Doob woke up the next morning, crawled out of the tent he had shared with Henry, and stood up and looked about, he immediately dubbed the place New Baikonur. It was at the same latitude as Baikonur and it was in the same sort of steppe country.

And like the steppe of old it was populated by nomads. Space Okies. At least ten thousand, he guessed.

They seemed orderly enough. Long straight lines had been chalked out on the dry lakebed, apparently with the same equipment used to stripe football fields. These delineated streets and avenues that, for the most part, were being respected by newly arrived tent pitchers. Portable toilets huddled at strict intervals, though Doob’s nose told him that some were using pit latrines, or just pissing on the sagebrush.

Henry had filled him in a little during the last hours of the drive. It had been an air force base, part of the northern line of defensive installations from which the U.S. would have defended itself against Communist aggression, had that ever been necessary. Its 13,500-foot runway suggested it might have had offensive purposes as well. It had been an alternate landing site for the Space Shuttle, never used. In any case it was ridiculously oversized for the town of Moses Lake and had tended to be used by the aerospace industry in recent decades for various training and experimental purposes. Blue Origin had used it to test a VTOL craft in 2005, operating from a trailer on the empty lakebed west of the airport where New Baikonur was arising now, and where Doob was walking about trying to track down the scent of frying bacon.

Some giant, windowless aircraft hurtled overhead, deploying a phalanx of tires from its belly, and made a long, slow landing on the big runway, using every one of the 13,500 feet. A cargo carrier.

He came to a broad avenue that led directly into the encampment’s center. And there was no mistaking where and what the center was: a concrete pad, still being poured one patch at a time, with a mixed assortment of cranes rising up from what he took to be its center.

They were assembling a rocket there.

It was a big rocket.

It all more or less made sense. There was no cargo too big to be barged up the Columbia River and then trucked the last few miles to Moses Lake. There was no airplane that couldn’t be accommodated by that runway. There was no object that the aerospace machine shops of the Seattle area couldn’t build. And from this latitude, the same as Baikonur, a well-worn and understood flight plan could take payloads to Izzy.

A mere four days later, Doob stood in the bed of a rusty pickup truck with a random assortment of space rednecks, hoisting a longnecked beer bottle into the sky in emulation of the rocket lifting off from the pad. They all hooted and screamed as they watched it arc gracefully downrange and take off in the general direction of Boise. And the next morning, when they had all sobered up, they got busy building another rocket.

DAY 80

“We talk about sending stuff to orbit as if orbit is a place, like Philadelphia, but it’s actually a lot of places, a lot of different ways to be in space. Any two objects in the universe can theoretically be in orbit around each other.

“Most of the orbits that matter to us involve something tiny orbiting around something huge, like a satellite around the Earth, or the Earth around the sun. So, a quick way to label and classify orbits is according to ‘What is the huge thing in the middle?’

“If the huge thing in the middle is the Earth, we call it a geocentric orbit. If it’s the sun, it’s a heliocentric orbit. And so on. Since the moon broke up, we’ve mostly focused on geocentric orbits. The moon, back when it existed, used to be in such an orbit; it revolved around the Earth. Most of its pieces still remain in geocentric orbits. A small number of those just happen to intersect the Earth’s atmosphere. When that happens, we get a meteorite.

“So much for Orbits 101. But keep in mind there can be different levels. So, the old Earth-moon system was, as a whole, revolving around the sun in a heliocentric orbit. And if you zoom way out and look at the entire Milky Way galaxy, you can see that our whole solar system is very slowly revolving around the black hole at its center, in a galactocentric orbit.”

The voice was that of famous astronomer and science popularizer Doc Dubois. The images accompanying it were an animation zooming in and out of the solar system. Dinah was getting snatches of it over the shoulder of Luisa Soter, a recent arrival to Izzy and hands-down winner of the “least like a traditional astronaut” competition. Born in New York City to parents who had fled political repression in Chile, she had been raised in a polyglot bohemian household in Harlem, walking through Central Park every day to the Ethical Culture School on West Sixty-Third. She’d followed that up with a succession of degrees in psychology and social work from UCLA, Chicago, and Barcelona. After a few years of work with economic refugees trying to enter Europe on leaky fishing boats, she’d been awarded a genius grant that had given her the freedom to travel the world for a few years doing research on other economic migrants.

Two weeks ago she’d been yanked out of a Fulbright scholarship at the University of St. Andrews in Scotland, given some basic training in how to live in space, strapped into a rocket, and shot up here in a tourist capsule.

Dinah, along with everyone else, made the obvious assumption that Luisa’s job was to be the first shrink and social worker in space. Judging from some interactions that had been happening as crowding and stress had gotten more intense, she was going to have her work cut out for her. A bunch of desperate people crowded aboard a pitching and rudderless fishing boat was an uncomfortably close match for the situation up here.

Luisa had a relaxed self-confidence that made it easy for her to admit that she knew absolutely nothing about such topics as orbital mechanics. But it was more than just that; she knew how to use her own ignorance as an icebreaker in conversations. Izzy was full of people who were skewed toward the Asperger’s end of the social spectrum, and there was no better way to get them to start talking than to ask them a technical question.

But when everyone else was busy, Luisa was not above googling her question down to Earth and latching on to a YouTube video, as she was doing now.

Dinah, floating behind Luisa’s shoulder, watched as the animation was replaced by a live shot of Doc Dubois and a stocky, bald white man standing next to each other on the flat pan of gray-brown dirt that she now recognized as the Moses Lake spaceport. In deep background behind them was another rocket being stacked on the pad, one stage at a time, by a tangled-looking arrangement of cranes, gantries, and cables.

Dinah vaguely recognized the one who wasn’t Doc Dubois; he was a tech pundit who popped up frequently on television and YouTube. He turned toward the camera and spoke: “This is Tavistock Prowse, coming to you from the world’s newest spaceport here in Grant County, Washington. I’m here with a man who needs no introduction, Doc Dubois, to talk about some of the recent controversial events surrounding the Arjuna Expeditions launches, many of which are originating from the improvised launch complex that you can see directly behind us. Arjuna has prepared an animation that explains what they are all about. So pop some popcorn and pull up a chair.”

Their image was replaced by a view of Earth that zoomed back, tilted, and panned to show it in its orbit around the sun. This was helpfully traced out by a thin, curved red line. The animation panned back. The orbits of Venus, Mercury, then Mars and Jupiter came into view. “Traditionally,” Doc Dubois said, “when we talk about asteroids, we’re talking about the asteroid belt, which is out between Mars and Jupiter.”

A ring of dust, with a few larger clumps, was now spattered into the huge gap between those two planets’ orbits. “There’s a lot of material out there that Our Heritage might one day be able to exploit, but it’s too far away to be easily reached by any spacecraft we have now.”

So Doc Dubois, in keeping with his rep for staying in touch with the zeitgeist, had adopted the Our Heritage phrasing, a suddenly popular buzzword and hashtag meaning “whatever gets accomplished in the distant future by the descendants of the people who make it onto the Cloud Ark,” or, to put it bluntly, “the only reason to go on living for the next twenty-two months.”

The animation began zooming back in, to the point where it showed nothing beyond Earth’s orbit. “But astronomers have known for a long time that not all of the asteroids are out beyond Mars. There are much smaller—but still significant—populations of asteroids in heliocentric orbits not that different from Earth’s.”

A finer and sparser dust of particles was now drawn in, forming a sort of fuzzy halo around the red line that represented Earth’s orbit.

“And that’s where Amalthea came from, is that correct, Doc?”

“Yes, bringing a hunk of metal that big from all the way out between Mars and Jupiter would have taken forever. Because we found it in an Earth-like orbit, it was a little easier.”

“And what do you mean by an Earth-like orbit?”

“These rocks all revolve around the sun just like the Earth. Some are a little inside Earth’s orbit, some a little outside of it, some cross the Earth’s orbit twice every time they go around the sun. We used to worry about those.”

“Now, not so much,” Tav put in.

Doc paused, and apparently thought better of acknowledging the joke. “Because we were worried about them, we made an effort to find them and to know their exact trajectories—their orbital parameters.”

Back to Doc and Tav, now walking across the pounded earth of the spaceport with a big truck in the background emblazoned with the Arjuna Expeditions logo.

“In recent years, companies like Arjuna Expeditions have mapped a whole lot more of those asteroids in the hopes of mining them. What we’re seeing in the last few weeks is a concerted effort by Arjuna, and an alliance of other private space companies, to throw those efforts into high gear.”

“What exactly is Sean Probst thinking, Doc?” Tav asked.

“He’s not telling us. But the science of orbital mechanics doesn’t leave a whole lot to the imagination. In Part Two of this video, you can learn more about the dance of orbiting bodies in space, and the intricate choreography needed to make an asteroid show up in the right place at the right time.”

Luisa’s finger hovered over the link that would play the next video, but before tapping it, she turned around to look at Dinah. “Just trying to figure out what you do for a living,” she said, in an accent that came from everywhere, but mostly from New York. “You’re with Arjuna, right?”

“Shh!” Dinah warned her jokingly. “I’m still trying to stay friends with the Russians.”

“What’s that about?” Luisa asked.

She was referring to a recent series of testy meetings, and sometimes out-and-out confrontations, between the Russians—still thinking and acting as a bloc under the leadership of Fyodor Antonovich Panteleimon—and the Arjuna contingent, which actually prided itself on being “disruptive.” This was a commonplace bit of biz jargon. But try explaining to a grizzled cosmonaut why being disruptive was a good thing.

Dinah was inclined to say something like “It’s cultural,” but she felt a little intimidated about using that sort of cocktail-party banter around someone with Luisa’s credentials.

“Look, surprises in space are almost always bad,” Dinah said. “Traditionally, every mission is planned out to the nth degree, and there’s a contingency plan for everything. You don’t improvise. You can’t improvise, because there’s nothing to improvise with.”

“I’m just remembering the duct tape in Apollo 13.”

“Yeah, that was one of the rare exceptions,” Dinah said, “and people are still talking about it decades later. So, to the Russians, the idea that someone can just show up unannounced, and make a claim on our resources—”

“What resources?” Luisa asked.

“They’re breathing our air,” Dinah said. “Taking up space, using bandwidth, you name it. Larz hitched a ride up here on the assumption he’d stay on Izzy and work for us—instead he’s taking off with Sean. And they are taking almost all of my robots.”

“But they’re sending more, yes?”

“Absolutely. Look, all I’m saying is that it was a surprise. And the sooner Sean and Larz get out of here, and on their way, the less likely it is that Fyodor is going to strangle them with his bare hands.”

“On their way to where?” Luisa asked.

“A different orbit.”

“Heliocentric or geocentric?” Luisa asked, deadpan, then gave Dinah a wink.

“Geocentric first. Then heliocentric,” Dinah answered with a trace of a smile.

“But I thought we were already in a geocentric orbit.”

“The wrong one, as far as Sean is concerned. Izzy’s orbit is angled with respect to the equator. It has to be that way so Baikonur can launch to it—Baikonur is as far north as Seattle. But when you are doing interplanetary stuff, which is what Sean has in mind—basically, whenever you want to get out of low Earth orbit—you want to be in an orbit that’s closer to the equator. Because that’s pretty much where the rest of the solar system is—including the big chunk of ice that Sean wants to grab and bring back here.”

“Ymir,” Luisa said, pronouncing it as she’d heard Sean do: ee-meer. A word from Norse mythology referring to primordial ice giants. Sean’s code name for a particular hunk of ice that his project had identified, and that he meant to bring back.

“Yeah. Not an official name. Sean doesn’t divulge much.”

“And how do you get from one to the other?” Luisa asked. “From a geocentric orbit—that’s what we’re in now, right?”

“Yes.”

“To a heliocentric one?”

“Well, first he’s going to have to do a plane change—from the angled Izzy orbit we’re in now, to one closer to the equator. He’ll rendezvous with the rest of his gear.”

“Why didn’t they just send everything up here?”

“Plane-change maneuvers are expensive. It’s not too bad if the only thing plane-changing is Sean and Larz and a Drop Top, but it would be ridiculously wasteful to send the whole expedition package up here only to plane-change later.” Dinah didn’t mention the other reason, which was that the biggest part of Sean’s package was so screamingly radioactive that it couldn’t be allowed anywhere near Izzy.

“Okay. But we’re still talking geocentric, right?”

“Correct, we’re still just a few hundred miles high.”

“So, how do they get from the rendezvous point to a heliocentric situation?”

“There’s a bunch of different ways to do it,” Dinah said, “but if I know Sean he’ll go through the L1 gateway.”

“I have no idea what that is,” Luisa said, then finally lost a fight to suppress a giggle. “But once again I feel that I have been dumped into a sci-fi movie when I hear people around me talking like that.”

“Doc Dubois probably covers it in that video,” Dinah said, nodding at Luisa’s tablet, “but the gist of it is really straightforward.” Looking around, she spied a mesh bag stuffed with clothing. She pulled it out of its niche and let it drift in the center of the cabin. “The sun,” she said. Now patting herself down, she found in her pocket a small plastic bottle of pills—antinausea medication she had fetched for one of the new arrivals. She opened it up and pulled out the ball of cotton stuffed into its top, then let the cotton drift in the air a little closer to Luisa. “The Earth, in its heliocentric orbit.” The sick crew member would have to wait for a few minutes. Dinah carefully tapped a few pills free from the bottle’s open neck and let them float for a moment while she pocketed the bottle. Then she began to arrange the pills in the space already staked out by the “sun” and the “Earth.”

“Asteroids?” Luisa guessed.

“These are more like abstract mathematical points,” Dinah said. “They’re called the Lagrange points, or the libration points, and there’s five of them around every two-body system. Always in the same basic geometry. Two of them, L4 and L5, are way off to the sides. I’m not going to try to show you those because we don’t have room. But the other three are all along the line running between the sun and the Earth.” She pushed off and glided to the far side of the “sun” and stationed a pill there, exactly on the opposite side from where the “Earth” was. “This is L3, very far away, invisible to us because the sun’s always in the way, not that useful.”

Gliding back toward the hovering cotton ball, she stopped herself against a bulkhead and placed a second pill out beyond it. “This is L2, outside of Earth’s orbit.” Finally, she put a pill in between the “sun” and the “Earth” but much closer to the latter. “And this is—”

“L1, by process of elimination,” Luisa said drily, and laughed. “You space people love to count down, I know your ways.”

“It’s where the gravity of the sun and the Earth balance,” Dinah said, “and people sometimes call it a gateway because it’s an easy place to effect a switchover between a geocentric and a heliocentric orbit. This even happens naturally sometimes: an asteroid in a heliocentric orbit will wander close to L1 and get captured by the Earth. Or, going the other way, there’s a case where an Apollo upper stage orbiting around the Earth passed near L1 and got ejected into a heliocentric orbit for a number of years. Later it came back through the same gateway—only to get ejected again.”

Luisa nodded. “Like changing from the D to the A train at Columbus Circle, in New York terms.”

“A lot of people have used the analogy of a switching yard or a train station to describe it, yeah,” Dinah said.

“So you think Sean and his crew are headed that way.”

“Once they get all their—” Dinah paused.

“Their shit together?” Luisa suggested.

“Thank you, yes,” Dinah said with a smile. “They need to get to a higher orbit than we are in now if they are going to reach L1. That means burning their engines, expending a lot of fuel in just a few minutes, and then coasting for a few weeks. They’ll have to pass through the Van Allen belts and soak up a lot of radiation. No avoiding it, unfortunately. L1 is four times farther away than the moon.”

“Or what used to be the moon,” Luisa said under her breath.

“Yeah, which means that in a few days Sean and his crew are going to be farther away from Earth than any humans who have ever lived. When they get to L1—which will take five weeks—they’ll have to execute another burn that will switch them from the D to the A train—place them into a heliocentric orbit. And from there they can plot whatever course is going to get them to the comet.”

Luisa had gotten a bit sidetracked by the first part of what Dinah had said. “Farther away from Earth than anyone in history,” she repeated. “I wonder if there might be a certain feeling of jealousy at work in Fyodor’s reaction, knowing that after all the time he has spent in space—”

“Some rich whippersnapper is going to show up and make his accomplishments look minor,” Dinah said, nodding. “Could be. Fyodor’s got the Russian granite face, you can’t tell what’s going on inside.”

“Anyway,” Luisa said, “they go and fetch the big ball of ice and then reverse all of those steps to come back to what by that point will hopefully be the Cloud Ark.”

“Not exactly,” Dinah said. “And that’s where things get interesting.”

“Oh, I thought they were already pretty interesting!” Luisa said.

Dinah was limited, here, in what she was allowed to say. “Maneuvering a space vehicle—which is designed and engineered to be what it is—around the solar system is one thing. Moving a huge raggedy-ass ball of ice is another.”

“It’s going to take a long time,” Luisa said, nodding. “And it might not work.”

“Yeah. Look, I just make robots.”

“All of which will be making the trip?”

“Yes,” Dinah said. “They’ll be needed on the comet’s surface, for anchoring cables and netting. It’s a big chunk of ice. It’s brittle. We don’t want it to fall apart like a dry snowball when thrust is applied.”

“A dry snowball,” Luisa repeated. “Is that a thing, where you come from?”

“The Brooks Range? Yeah. Terrible place to make snowballs.”

“Unless you’re the kid sister,” Luisa said, “and everyone’s throwing them at you.”

“No comment on that.”

“In Central Park,” Luisa said, “the snowballs were wet and they were hard.”

DAY 90

When Ivy had opened the meeting on Day 37 with the words “five percent,” Dinah and most of the others on Izzy had looked around themselves and seen a lack of progress that had troubled them. Which, of course, had been Ivy’s point. On that day, twenty-six people had been in space, eight of whom were just barely surviving in temporary Luk shelters. The Banana had, with a bit of crowding, accommodated everyone.

On Day 73, when Ivy had opened another meeting in the Banana with the words “ten percent,” the situation had been transformed. There had been no question anymore of fitting Izzy’s whole population into the Banana; most of them had had to watch the meeting on video feeds. Thanks to Sean Probst and his Arjuna launches out of Moses Lake, no one quite knew what the total off-Earth population was anymore. Allegedly there was a Google Docs spreadsheet where it was being kept track of, but no one could agree on where it was. The population had certainly gone into the triple digits at least a week before.

In the first two weeks of its operation the new shake-and-bake spaceport at Moses Lake had launched three rockets. One had crashed into a high-end vineyard near Walla Walla, destroying several acres of grapes that would have made excellent wine, had there been enough time left on Earth’s clock to age it properly. The others had made it to Izzy.

Most of Arjuna’s big payloads, though, were being launched not from Moses Lake but from sites nearer the equator, whence they could get into orbits closer to the plane of the ecliptic. At least two heavy-lift rockets, one from Canaveral and one from Kourou, had effected a rendezvous and docking maneuver in a low orbit above Earth’s tropics. Others were said to be in the works. But little was known of this project. Communication wasn’t Sean Probst’s strong suit, and his career in private enterprise had instilled a habit of playing his cards close to his vest. In this he seemed to be of one mind with the small cohort of people aboard Izzy, like Spencer Grindstaff and Zeke Petersen, who had impressive security clearances. Dinah and Ivy, comparing notes and sharing fragments of circumstantial evidence, had assembled at least a vague theory of what was going on. Ostensibly, Sean Probst was a wild card. But Arjuna had been mailing Nats to Sparky for weeks, and Sparky had been giving them top priority on launches to Izzy. It seemed, therefore, that Dinah’s results—the feedback she was sending to Arjuna about which Nats worked in space and which didn’t—were of great interest to NASA. And it was significant that at least one of Sean’s payloads had been launched from Canaveral—which was, of course, NASA’s flagship launch facility. Even more so was a launch out of Vandenberg Air Force Base that added a small additional module to the growing Arjuna complex. They knew it was small because of the size of the rocket used, and they knew it was top secret spook stuff because of the precautions that had been taken on the ground—that much had been reported by ordinary citizens, who had been forced to the shoulder of Highway 101 by a long military convoy, and who had aimed long lenses at the launch pad only to find their view blocked by tarps and camo nets.

The next rocket out of Moses Lake had made an uneventful journey to Izzy. Its upper stage, lacking a place to dock, flew in formation with the space station about a kilometer “aft.” Fyodor stared at it balefully out the window and made repeated suggestions that its stores should be confiscated. Its cargo manifest was unusual:

 Spare propellant, and other consumables, that would enable Sean’s Drop Top to execute a plane-change maneuver and rendezvous with Ymir in equatorial orbit (for the word “Ymir” was now being used to denote both the spaceship that Sean was assembling and its faraway destination)

 Ice

 Fiber for combining with ice to make a stronger material called pykrete

 Several thousand Icenats: tiny robots optimized for crawling around on ice

Fyodor, and perhaps others as well, coveted the ice and the propellant. Pete Starling had begun rattling legal sabers down on the ground, threatening to seize the Moses Lake spaceport—a scheme that vanished overnight after Sean began to rattle sabers of his own, threatening to make a YouTube video exposing the Cloud Ark scheme as a poorly conceived panacea at best. It was strange, to say the least, that such open conflict could exist between the government’s left and right hands, but the world had become a strange place. Talking of it over meals or during after-work drinking sessions, Dinah and Ivy and Luisa could only speculate at the shouting matches that must be happening down on the ground between the Oval Office, the military, Arjuna Expeditions, and the Arkitects.

Dinah mostly just kept her head down and worked, programming the robots that Sean was going to take with him on his expedition. A comet core was not a solid piece of ice so much as an aggregation of shards, loosely held together by its own self-gravity—which was extremely weak. Merely touching it could cause big pieces to separate. Arjuna Expeditions had known this for many years and had put millions of dollars into inventing technology for capturing such difficult objects. Though “technology” might be too fancy a word for techniques that would have been recognizable to Stone Age hunter-gatherers: surround it with a net, draw the net closed with a loop of string.

Actually performing that feat in space was what Sean described as “an asymmetrical problem,” programmer-speak meaning that there were a lot of contingencies and detail work, so it wasn’t amenable to One Big Solution. Robots would probably end up swarming all over the surface of Comet Grigg-Skjellerup, cinching the net down and reinforcing weak spots by melting the ice, mixing the water with fiber, and letting it refreeze into pykrete. Dinah had offered to help out with that, and had been excited by the thought until Sean had brought her down to earth by pointing out some awkward realities. Communication between Izzy and Ymir was going to be limited by their one radio. They wouldn’t be able to send video. And latency was going to be significant: for a large part of the journey there would be a delay of several minutes as the signals traversed a distance comparable to that between the Earth and the sun. So programming robots on the surface of the comet would be nothing like looking out her window at the ones on Amalthea. Anything Dinah had to contribute, she had to contribute now.

In any case, Izzy’s population had dropped by two, and the level of tension and drama had fallen precipitously, when Sean and Larz had departed in the Drop Top on A+0.82. The plane-change maneuver took them to a rendezvous above the equator with Ymir. After more rendezvous operations extending over a week, and incorporating yet more payloads launched from Cape Canaveral as well as from private spaceports in New Mexico and West Texas, Ymir made a long burn of her main engine that placed her into a transfer orbit bound for L1. A few days after that, she beat the Apollo record for distance traveled from Earth.

Konrad Barth came to Dinah’s shop and knocked politely, for she happened to have her curtain drawn, and everyone knew that she and Rhys sometimes had sex on the other side of it. He entered, looked about nervously, and asked her if she knew anything about what Ymir was going to do. Before she could answer, he shook her off, took out his tablet, and tapped in his password. Then he spun it around to show her a photograph.

It took her a while to understand what she was seeing. Clearly, it was a picture of a man-made object in space. And it was a good picture, but surrounded by a glamor of pixels that spoke of considerable enhancement. Konrad had taken the picture using one of Izzy’s optical telescopes. He had turned it away from its usual objective, which was the system of fragments churning around the former center of the moon, and aimed it at this man-made object. The object was big and complicated, at a guess the largest thing humans had ever assembled in space with the exception of Izzy herself. The picture had been taken from a great distance while both Izzy and the object were moving with respect to each other, and he’d toiled with image processing software to reduce the blur. She could see clearly enough that, like Izzy, it consisted of a stack of modules that had been sent up atop different rockets and plugged together. The one on its tail sported a large nozzle bell, and was obviously its main propulsion unit. Some of the modules just looked like propellant tanks. Others looked like habitations. But far and away the most prominent, and the weirdest, part of this thing was a long spike or probe that extended from its forward end, making it ten times as long as it would have been otherwise. It was a truss, recognizably made in the same way as the new trusses on Izzy.

“Wow,” Dinah joked, “a space station with its own radio tower!”

Konrad smiled weakly. “Look at the ‘top’ of the ‘radio tower,’” he suggested. He spread his fingers on the tablet, zooming in on a thick blur of pixels at its tip. This seemed to have a roughly arrowhead-like shape, a small dark tip sitting on a thicker white base, itself resting on a dark base plate.

He was looking at her as if he expected her to understand—or as if she must be privy to secrets.

Which she was. But she couldn’t reveal them.

“I’m not a nuclear physicist,” she said, “but it’s screamingly obvious that the people aboard that ship—it’s Ymir, isn’t it—?”

“Of course.”

“—that they want to be as far away as possible from whatever that is, and so they mounted it at the end of the longest stick they could build.”

“It is something that makes a lot of neutrons,” Konrad said.

“How do you know that?”

“This thing”—he indicated the fat white layer in the middle of the sandwich, like the marshmallow in a s’more—“is probably polyethylene or paraffin, which would be good at absorbing neutrons. Gamma rays might be produced in the process, and so this base plate”—he pointed to the dark graham cracker at the bottom—“is probably lead.”

Dinah already knew what it was, because Sean had told her: the core of a large nuclear power plant, rated at a thermal output of four gigawatts, somewhat hastily reengineered for this purpose. But she had been sworn to secrecy, and so all she could do was let Konrad piece it together himself. “Well,” she said, “those are impressive precautions on what is probably a suicide mission anyway.”

“They want to be alive and capable of doing something when and if they get where they are going,” Konrad said.

“Do you suppose anyone has taken pictures like this from Earth?” Dinah asked. “Because I haven’t seen anything in the media.”

“It was concealed by a fairing until they made their transfer burn,” Konrad said. “I took this a couple of hours ago, when I had my one and only clear shot.”

They had timed that burn so that they would cross the former moon’s orbit at a time when most of the debris cloud was on the opposite side of the Earth, thus minimizing the chance of colliding with a rock.

Nevertheless, a few days after they had passed that distance, and become the longest-range travelers in human history, they stopped communicating.

Until then Ymir had been using powerful X-band radios to communicate over the Deep Space Network—a complex of dishes in Spain, Australia, and California that had been used for decades to talk to long-range space probes. Now she had gone silent. She was still out there—Konrad could still pick her up as a white dot on his optical telescope. Since she was merely coasting for thirty-seven days, not firing her engines, there was no way to tell whether the crew was still alive. A perfectly shipshape Ymir and a crumpled wad of space junk would have looked and behaved the same.

They drew some hope from the fact that nothing came back from her. Ymir had automatic systems that were supposed to phone home without human intervention. If those had continued to function while communication from humans had ceased, it would suggest that the crew were all dead or incapacitated. But the fact that all human and robotic signals had been cut off at the same time suggested that it was a radio problem—perhaps damage to the X-band antenna, or to the transmitter itself.

Ymir became tricky, then impossible to see as she approached L1, since that put her squarely between Earth and the sun. She was assumed to have reached that point on Day 126, whereupon she was scheduled to make another burn that would put her into a heliocentric orbit: an ellipse that would intersect with “Greg’s Skeleton” over a year later—sometime around A+1.175, or a year and 175 days post-Zero. Once Ymir disappeared, from their point of view, into the fires of the sun, there was nothing they could do except wait for her to reach a place where she was observable. If Ymir had suffered a catastrophic failure and been turned into a floating piece of space junk, she would probably cycle back on the return leg of the same orbit and pass close to the Earth again—though L1 was such an unstable place from an orbital dynamics standpoint that she could just as easily wander off into a heliocentric orbit, especially if she’d taken a big hit from a rock that had knocked her off course.

As the calendar progressed through the 130s and to Day 140—two weeks after Ymir ought to have passed through L1—and she did not appear on that return leg, it became clear that she must have transferred to a heliocentric orbit, whether by accident or because of a controlled burn. Assuming the latter, Sean and the other half-dozen members of the crew would have nothing to do for the next year but float around in zero gee and wait. There was nothing that could be done to speed up the journey; it was a matter of getting two orbits to graze each other.

These events, which would have seemed of world-historical significance a few months ago, now seemed like below-the-fold news compared to all that was happening in what had formerly been the sublunary realm.

The fuss and excitement surrounding Sean and Arjuna, the Moses Lake spaceport, and the voyage of Ymir had drawn attention away from the routine, faithful, grind-it-out progress being made the whole time by NASA, the European Space Agency, Roskosmos, China National Space Administration, and the space agencies of Japan and India. These organizations were staffed by conservative old-line engineers, not far removed culturally from the slide-rule-brandishing nerds of Apollo and Soyuz fame. In fact, some of them were those nerds, just a lot older and a lot crustier. They were baffled, nay, infuriated by the ease with which a few upstart tech zillionaires could command the world’s attention and go rocketing off on ill-advised, hastily planned missions of their own choosing. The departure of Sean and Larz from Izzy had occasioned a big sigh of relief, and a return to the steady and unimaginative work that these people were best at.

And anyone paying attention to the numbing details expressed in the spreadsheets and the flowcharts would see the value of that work on A+0.144, when Ivy opened a meeting in the Banana with the words “twenty percent” (for the latest projections from the astrophysical lab of Dr. Dubois Jerome Xavier Harris at Caltech, and from the other labs doing the same calculations at other universities around the world, were that the White Sky would happen on or about A+1.354, or one year and 354 days after the breakup of the moon; they were one-fifth of the way there).

The purpose of the Scouts—the first wave of what amounted to suicide workers such as Tekla, who had arrived starting on Day 29—had been to build out the improvised network of hamster tubes and docking ports that would make it possible for a much larger population of so-called Pioneers to reach Izzy. The basic distinction between a Scout and a Pioneer was that the Scout went up knowing there was no place to dock, but the Pioneer knew that, at least in theory, there would be an available port for their spacecraft, with pressurized atmosphere on the other side of it. The promise had failed in one case, with the result that half a dozen Pioneers crammed aboard a Soyuz had silently asphyxiated. The problem was traced to a defect in a hastily built docking mechanism. Three Chinese taikonauts lost their lives when the hamster tube in which they were moving was pierced by a micrometeorite and lost pressurization. But from about Day 56 onward, Pioneers were arriving at a rate of between five and twelve per day. There was a lull once all the available docking spaces were occupied, but after that it began to snowball as spacecraft began to dock to other spacecraft, and the hamster tube network was built out, and inflatable structures were deployed.

Izzy, which had been a complicated and hard-to-understand contraption even before all of this had happened, was now an utterly bewildering maze of modules, hamster tubes, trusses, and ships docked to ships docked to ships, “like a freakin’ three-dimensional domino game,” as Luisa put it. The only way to get one’s bearings, looking at a rendering of the complex, was by picking out the rugged and asymmetrical shape of Amalthea at one end and the two tori at the other. Those were “forward” and “aft,” respectively, and the axis between them was the basis for the traditional nautical directions of “port” and “starboard” as well as “zenith” and “nadir,” which were space lingo for basically “up away from Earth” and “down toward Earth.” If you arranged yourself so that your back was to the tori and your face toward Amalthea, with the “port” stuff on your left hand and the “starboard” stuff on your right, then your head would be aimed toward the zenith and your feet toward the nadir and the surface of Earth four hundred kilometers below.

That, however, was the privileged view of people outside the thing in space suits. Inside, it was still easy to get lost in the three-dimensional domino game. Felt-tip markers, always a scarce resource even on Earth, became objects of great value as people used them to mark directions on the walls of hamster tubes and habitat modules.

“IT’S JUST A CHRONOLOGICAL ACCIDENT THAT I’M HERE AT ALL,” IVY mused, during one of her and Dinah’s increasingly rare drinking sessions. All of their original stashes of booze had long since been consumed, but new arrivals were kind enough to slip them bottles from time to time.

“I disagree,” Dinah said. It wasn’t exactly a scintillating response. But she’d been caught off guard by the suddenness with which Ivy had dropped her guard.

“If the moon had blown up two weeks later, some Russian sourpuss would be in charge up here and I’d be on the ground, married and pregnant.”

“And under the same death sentence as everyone else.”

“Yeah, well, there’s that.”

Dinah reached for the bottle and refilled the shot glasses, trying to stretch out the moment. It had never been easy to get Ivy to open up, even back in the happy days before Zero.

“Look, Ivy, it’s not an accident that you were in charge of Izzy. They gave you the job for a reason. You’re the last girl in the world—or out of it—who should be suffering from impostor syndrome.”

Ivy stared at her through a somewhat amused silence. “Go on,” she finally said. “What is this impostor syndrome you speak of?” For they’d talked about it before—but usually with Dinah being the one who felt it.

“Don’t try to deflect this. What’s going on?”

Ivy glanced at the ceiling: a sort of visual signal, borrowed from the Russians, to remind Dinah that you never knew when someone was listening. Then she looked into Dinah’s eyes. But only for a moment. She was fundamentally a shy person, who preferred inspecting her shoes while baring her soul.

“You and Sean Probst made great sparring partners,” Ivy said.

“He was so fucking obnoxious! He needed someone to—” Dinah cut herself short then, because Ivy had gotten a sort of sad, wry look on her face and held up one hand to stop her.

“Agreed! Yes. Thanks for doing it,” Ivy said. “He needed someone like you around. Sometimes it almost looked like a comedy act between you two. And the way that the Russians reacted to him—Tekla first of all, of course, but later Fyodor proposing to place all Arjuna personnel under arrest and confiscate everything they’d brought up with them—that was great drama. Tabloid stories and comment threads galore down on the surface. But I barely survived it.”

“What do you mean, you barely survived?”

“You wouldn’t believe some of the conferences I had with Baikonur and Houston. People down there wanted me to take a very hard line. To do what Fyodor wanted.”

“But you didn’t,” Dinah pointed out.

Ivy met her gaze again. Then, after a moment, she gave a little nod.

“So you won,” Dinah went on.

“I won a Pyrrhic victory,” Ivy said. “I negotiated a less draconian solution. The Ymir expedition went on its way with no obvious hard feelings.”

“And how is that Pyrrhic?”

“I don’t want to make my problems yours,” Ivy said.

“Who else are you going to talk to?”

“Maybe no one,” Ivy returned, showing a flash of something like anger. “Maybe that’s what a leader is, Dinah. The one person who can’t—who shouldn’t—share her problems with anyone else. It’s sort of an old-fashioned idea. But the human race might need such people going forward.”

Dinah just stared back at her. Finally, Ivy relented, and spoke in tones almost devoid of feeling: “My position as the head of the space station came under serious challenge. It made me aware of politics on the ground that have been going on for some time—but that were invisible to me until the Sean Probst controversy surfaced them. Since then, I believe that my authority has been further undermined by people on the ground, leaking things to the press, saying things in meetings.”

“Pete Starling.”

“No comment. Anyway, I think I am going to be replaced before long.”

Ivy’s eyes had reddened slightly. She made another glance at the ceiling, but the expression on her face suggested she didn’t care who might have heard her. Then she looked at Dinah and smiled. “How have you been doing, sister?” she asked in a weak voice.

“I’ve been pretty good,” Dinah said.

“Really? That’s music to my ears.”

“Bo, Larz, the others who’ve come up to work in my crew, they seem to respect what I’ve done,” Dinah said.

“I think it’s because of what you did for Tekla,” Ivy said.

“Oh really? Not just my amazing natural competence?”

“There are a lot of people on the ground who are competent in the way you mean,” Ivy said, “and we are going to be seeing a lot of them up here in the next few weeks. Believe me. I’ve read their CVs.”

“I’m sure you have.”

“But everyone kinda senses now that some other qualities are going to be needed besides just pure competence. That’s why people are deferring to you.”

Another awkward silence. Ivy seemed to be suggesting that she, Ivy, was no longer being given that kind of respect.

“That, and your amazing competence,” Ivy added.