“Yes, I understand that. I will do so.” He paused, signaling a change in topic. “It is not exactly decentralized.”

Moira nodded. “If that thing gets hit with a rock ten minutes from now, all of the samples are destroyed.”

“Yes. That is my concern.”

“Mine as well. It all boils down to statistics and mathematics. For now, there aren’t that many rocks, and we can see them and avoid them if necessary. Keeping all the eggs in one basket . . .”

“And sperm,” Dr. Andrada said, in what had become the oldest joke in Moira’s personal universe.

“. . . is actually a safer bet, for the next couple of weeks, than trying to distribute them among all of those arklets. But there is a plan, Dr. Andrada, for so distributing them, which will be triggered when the BFR breaks through a certain threshold.”

He nodded. “Please call me Miguel.”

“Miguel. Moira, if you would.”

“Yes. Now, you know why I was chosen to come up here.”

“You figured out a way to make photosynthesis in rice more efficient by transplanting genes from maize. Greenpeace destroyed your research facility in the Philippines but you kept the project alive anyway, in Singapore. Starting shortly after Zero you began developing strains of that rice adapted for cultivation in low-gee hydroponic environments.”

“Sprice,” Miguel said, with an ever-so-slight roll of the eyes. The term, a contraction of Space Rice, had been coined by an enthusiastic reporter for the Straits Times and become an unkillable staple of tabloid headlines and Internet comment threads. “Do you understand, Moira, that it cannot grow without some amount of simulated gravity? There has to be an up and a down or the root system cannot develop. In this it is more difficult than algae, which doesn’t care.”

“Oh, we’re all going to be eating algae for a long time,” Moira said. “Sprice will come later, after we have constructed more environments that rotate to make gravity. And then, Miguel, then!”

“Then what?” Miguel asked.

“Sprew.”

“Sprew?”

“Space brew,” Moira said. “It’s not as good as barley, but you can make beer from rice in a pinch.”

“TAP,” MARKUS SAID. HE HAD TO SAY IT BECAUSE HE COULDN’T DO IT. The traditional way for a wrestler to tell his training partner that an unbreakable submission hold had been achieved was by tapping him or her on the hand, arm, leg, or whatever could be reached. But Markus couldn’t reach anything. Tekla had both of his arms controlled.

She let go of him moments before they drifted into the padded wall of the Circus—a large, mostly empty module reserved for exercise—and they raised their hands to absorb the impact.

Watching interestedly from the far side of the Circus were Jun Ueda, an engineer named Tom Van Meter, Bolor-Erdene, and Vyacheslav Dubsky. The three men were taciturn. Bolor-Erdene, who was nothing if not enthusiastic, permitted herself three claps, then stopped when it became clear that no one else was joining in.

“Okay,” Vyacheslav said. “Seeing is believing. It is possible to perform Sambo in zero gravity.” His eyes flicked in the direction of the others. “Or jujitsu, or wrestling, or bökh, I presume.”

“Obviously there are no throws. None of that shifting of the weight that is so important on the ground,” Markus said.

Jun nodded. “It is a subset. A little bit like ground fighting. But without the ground.”

Tom Van Meter, who’d been a collegiate wrestler en route to an engineering degree at Iowa, turned himself around to face the padded wall, then tried delivering a punch. In spite of his considerable size and strength, it landed weakly and sent him drifting backward across the module.

“We experimented with that too,” Markus said. “Punches are problematic.”

Just before striking the opposite wall, Tom flung both arms outward and slapped the mat to absorb energy. “If you’re in a torus, or a bolo, all the usual stuff is going to work,” he said. “But you’re right, martial arts in zero gee is a new frontier.”

“Once you have come to grapple,” Tekla said, “not so different.”

“The Cloud Ark is equipped with a dozen Tasers,” Markus said. “I did not request these. They were here when I arrived. No one knows about them. I am not comfortable with having some persons go around with sidearms—even if they are just Tasers—while everyone else is unarmed. And yet. We have a population of two thousand or so. There is no town on Earth of such a population that does not have police. There will be crimes. Disputes.”

“What does the Constitution say about police?” Bolor-Erdene asked. “I haven’t read it.”

All of the others laughed, appreciating her. “No one has read the bloody thing, Bo; it is this thick when you print it out!” Markus said, holding his thumb and index finger two inches apart. “Written by committee, as you would expect.”

“To be clear, Markus,” said Jun. “You are not suggesting—”

“No, Jun, I am not saying we ignore it. Believe me, I am screaming at these guys every day to make it simpler, to give us the, what do you call it—”

“Cliff’s Notes,” Tom said.

“Yes. Before we fall off the cliff. A simple owner’s manual. But somewhere in there, a police force is mentioned. I grepped it. They will have to be citizen police at first—no professionals. I have studied your personnel records. I know that you are all trained in some sort of wrestling. Wrestling is the only form of organized violence that is actually usable aboard a space station, short of absolutely crazy shit.”

“How about stick fighting?” Tom asked.

“I knew you would ask because your CV mentions a little bit of escrima,” Markus said. “It is a reasonable idea. I have a question, though.”

“Yes?”

“Do you see any sticks?”

“Maybe we could grow some trees,” Bo suggested.

“That will take a while,” Markus returned. “And so I am simply asking you this, to spend a little bit of time each day getting together in this module to practice wrestling. It might come in handy.”

DOOB HAD SLEPT SO POORLY HE SUSPECTED HE HADN’T SLEPT AT ALL. But the clock said it was about dot 15. When he’d climbed into his sack it had said dot 9. He must have dozed off for a while. But he didn’t know when.

His nightly videoconference with Amelia hadn’t gone well. It hadn’t gone badly—they hadn’t raised their voices, or come to tears—but at first it had been all about what had just happened in Kourou, and after that there’d been a failure to connect. He’d noticed the same thing with Henry.

They were running out of things to say to each other. That was ghastly, but it was true. His family members were all preparing to meet their maker in two or three or four weeks. The government had been handing out free euthanasia pills to anyone who wanted them; thousands had already swallowed them and bodies overflowed the morgues. Mass graves were being dug with end loaders. Meanwhile, Doob was preparing for—to be blunt, to be honest—the greatest adventure of his life.

He wished, at some level, that they were already dead.

He had spoken those seemingly unspeakable words to Luisa several days ago and she had nodded. “Happens all the time,” she said, “with caregivers of terminal Alzheimer’s patients, or similar cases. An enormous sense of shame and guilt comes with it.”

“But Amelia doesn’t have Alzheimer’s, she’s—”

“Doesn’t matter. Seeing her, talking to her, makes you feel bad. And at some level, your brain wants the thing that makes you feel bad to go away. Simplest reaction in the world. Doesn’t make you a bad person. Doesn’t mean you have to give in to it.”

Those thoughts had led to more tossing and turning—if those were the right words for not being able to sleep in a loose sack in zero gravity—as he had wrestled with the question of “When?” Predicting it on Day 720, plus or minus a few, had been all well and good back on Day 360. But Day 700 was now approaching its end, and the “plus or minus” thing was seriously bothering him. Lately they’d narrowed it down to “plus or minus three days,” but that was in response to political pressure. It wasn’t a legit scientific move. And it meant something different to scientists. Laypersons understood it as “certainly between 717 and 723.” Scientists would instead say that if you could repeat the experiment of blowing up the moon a large number of times, and keep track of the time-to-White-Sky separately in each case, the numbers would fall into a normal distribution, a bell-shaped curve, with about two-thirds of the instances falling within that range.