At the same time there had been 305 occupied, free-flying arklets plus 11 spares that were attached to Izzy but not occupied. The free-flying ones had housed 1,364 people; the remaining 188 humans had lived aboard Izzy as members of the General Population. But at any given time, 10 percent of the Arkies had been rotating through Izzy, bringing its population on a typical day up to 324.

Prior to today’s disaster, 26 people had been killed in various mishaps, mostly smaller bolide strikes. Another 24 were now aboard the stolen MIV calling itself Red Hope, and if their claims were taken at face value, they would soon be en route to Mars.

Of the persons who had been aboard Izzy at the time of the disaster, 211 had been killed outright and another two dozen or so remained in critical condition. The number of living people aboard Izzy had therefore been reduced to 113. The General Population—the older, more experienced, highly trained specialists—had been reduced from 188 to 106.

At the moment of the disaster, 1,178 persons had been living in arklets. The distributed nature of the swarm, combined with the fact that many arklets had flown the coop with Julia, made it difficult to estimate casualties. The best estimate they currently had was that seventeen arklets had fallen victim, with assumed 100 percent loss of life, reducing that population to about 1,100. If that was correct, then the day’s full death toll had been close to 300.

In terms of arklet count, they’d started the day with 299 surviving, occupied arklets, a figure that had been reduced to 282 by the collision. Ten of them—a heptad and a triad—were attached to Red Hope, leaving 272. Approximately 200 were missing and presumed to have flown the coop with J.B.F. The remaining 70 or so had elected to stay behind and were still reporting in as members in good standing of the Cloud Ark. The 11 spares were still attached to Izzy and would be inspected for damage later.

The arklets still with them probably had a population of some 300. That plus the survivors aboard Izzy added up to a bit over 400. The population of J.B.F.’s breakaway swarm must then be something like 800 souls. She had taken two-thirds of the human race with her.

“God forgive me,” Doob said, “but right now I don’t even care about head count. The number I’m after is engines. Arklet engines. Until Dinah showed up with all of that ice, they were useless. Now, we have a way to fuel them. If we get them all pointed in the same direction, all pushing on Izzy, we can go on the Big Ride.” He paused to look at his notes. With his reading glasses down on his nose he suddenly looked a lot older to Dinah. She could only imagine how she looked. “Based on what you just told me, am I right in thinking we have—”

“About seventy,” Ivy said, “plus the eleven spares. We haven’t checked those yet, but on visual inspection they seem undamaged.”

“Eighty-one,” Doob said. “I like that number. A perfect square.”

“A perfect square of perfect squares,” Rhys put in.

“If we could come up with a structural system for ganging them in clusters of nine—just a three-by-three grid, with shared propellant feeds—and make nine of those clusters, and integrate them into Izzy’s structure somehow—that being the hard part—then we’d have an array of eighty-one engines. If those things all come on at full power when we pass through perigee, it’ll give us enough combined thrust to make a difference. I think we can make the Big Ride work with that level of power.”

“It’s a lot of structure,” Fyodor pointed out. “A lot, a lot, a lot.”

“We have a lot of raw materials to work with, don’t we?” Luisa asked. “I’ve seen rolls and rolls of that aluminum ribbon for feeding into the extruder machines.”

“It is a question of time,” Fyodor said. “Yes, we have a lot of material. But to assemble it with so few people is difficult. Atmosphere is growing, drag is increasing, orbit is decaying.”

Dinah looked across the table at Rhys. Rhys the biomimetic engineer, the man who had perhaps saved Ymir with his idea of turning robots into little, radiation-resistant Ben Grimms.

“We’ll build it out of ice,” Dinah said.

Rhys looked up at her, pondered it for a second, and nodded.

“Too brittle,” Fyodor said.

“I don’t think Dinah’s speaking of regular ice,” Rhys said. “She means the pykrete stuff they used on Ymir. Fiber-reinforced ice. It worked to hold the shard together. We can make it work here.”

Moira spoke up. “Perhaps I’m missing something, but I was under the impression that the ice was our propellant. Aren’t we going to melt it, and consume it, as we go along?”

“Yes,” Doob said.

“And doesn’t that mean that we’ll be consuming the structure that’s holding everything together?”

“Yes,” Doob repeated, “but it’s okay. Because the more of it we use, the lighter we get, and the less thrust we need. So it’s okay to sacrifice some structure as we go along.”

Sal had been listening intently. “I don’t mean to throw cold water on the idea,” he said. The pun—assuming he meant it as such—elicited a few groans. “But we’ve been hearing about radioactive contamination.”

“On the outer surface of the shard, yes,” Dinah said. “Microscopic motes of stuff that is super radioactive, stuck to the ice. Beta won’t penetrate our living spaces. We’ll have to be careful, though, not to track it inside. We can program robots to crawl around, look for those hot motes, and get rid of them over time.”

Sal looked unconvinced.

“I won’t lie to you,” Dinah said. “People are going to die of it.”

“But the trade is as follows,” Rhys said. “Izzy already has a massive battering ram of nickel-iron on her snout. Her flanks are vulnerable, as we learned today. Now we have the ability to shroud everything—the entire space station—in reinforced ice. Oh, it will dwindle over time. But through most of the Big Ride we’ll be living deep inside of a gigantic iceberg with a steel nose. I submit that the death toll from possible contamination will be minor compared to what we would experience if we went on the same journey unprotected.”

“What do you need to make it happen?” Ivy asked.

“Permission,” Dinah said.

“When did you ever ask for that before?”

The joke elicited a high-pitched laugh from the corner of the conference room. Heads turned toward Camila.

“Camila,” Ivy said, “we’ve hardly heard a word from you since we found you in the Shipyard. One of our witnesses there claims you may have saved Tekla’s life. You had the opportunity to escape with Julia. Instead you stayed behind to free the bound Shipyard workers. You saved their lives. Now you’re here among us. You must know how this looks.”

The look on Camila’s face made it clear that how it looked had never crossed her mind. She didn’t even get what Ivy was saying.

“Dear,” Luisa said, “people are going to say you are a spy who volunteered to be left behind.”

Camila held up a closed fist and opened it to reveal a small white plastic box, loose tape still dangling from it. “Julia’s bug,” she announced. “It was here.”

No one looked very convinced.

“She invited me to dinner at the White House,” Camila said. “She helped me pick out a dress. She introduced me to generals, ambassadors, movie stars. She wrote me letters on White House stationery. I was—I was in love with her. You can call me naive if you want. All right. I was naive. Until this morning. And then all of a sudden I saw. I saw what I was dealing with. I hate her now. And I hate myself for having been in love with her.”

“Best remember that, sweetheart,” Moira said. “Because she made the wrong choice today. And sooner or later, she’ll be coming back.”

“I’ll be ready,” Camila said.