“Yeah.” She smiled, tiredly. “In New Columbia, we might have bust away from Maclachlan’s politics and economics, but I’m afraid we took his theology with us…”

The Summa — the original written in 1266 — was a kind of theological Theory of Everything, White read. It united Christian practice with Aristotelian physics. White read about transubstantiation, for instance: the moment in the Catholic Mass in which the bread and wine held by the priest became the body and blood of Christ. The stuff might still look like bread and wine, but — according to Aristotle — the form and the substance of every object were different. And at the moment of transubstantiation, while the form was unchanged, the substance of the bread became that of Christ’s body… And so on.

“It makes a kind of logical sense,” Jackie said. “It just isn’t science. Which is why they’ve started teaching Aristotelian physics in the schools.”

That gave him a double-take. “Woah,” he said. “You’re kidding.”

“No,” she said. “The kids these days are getting the whole shebang. Even the cosmology: the spheres of Moon and sun, the fixed stars beyond… Technology is allowed to continue as long as it’s limited to practical, Earth-bound applications. Even low Earth orbit satellites are okay, because they are beneath the sphere of the Moon. But we’re not supposed to look up at the sky, for fear of getting scared. In greater Seattle, they’ve even banned telescopes… Xavier Maclachlan is putting us back at the center of the Universe, Marcus; he says he wants to heal the spiritual dislocation that science has caused.” She shrugged. “There are compensations. Aristotle taught the interconnectedness of everything; that’s not a bad thing for kids to learn. Look at the environment. Besides, who am I to say Maclachlan’s wrong, if it does make people happier?”

“It’s not right, damn it,” he growled, shocked.

“But you have to face the facts, Marcus,” she said. “To most people the Earth might as well be flat anyhow. The sun might as well be a disc of fire floating round the sky…”

“But I walked on the Moon.”

Her face hardened. “Not too many people care about those old Moonwalks nowadays, Marcus. Anyhow, you can see why I can’t make too much of a fuss about Paula. She’s gone to a place which — according to what my kids are being taught — doesn’t even exist.”

After a time, they ran out of things to say.

White stared into his coffee cup. The milk substitute, whatever it was, had created some kind of scum that swirled around on top of the coffee’s meniscus; when he drank, he tried to filter the shit through his teeth.

The two boys just ignored White, carrying on with their business as if he wasn’t there. There had been a time when it was different. There had been a time when any ten-year-old kid would have been as thrilled as all hell to have a Moonwalker come visit.

Paula’s message ran out. At the end, Benacerraf seemed to be trying to say something a little more personal — I love you, I miss the kids — but her face just hovered on the wall, mute and distressed and inarticulate.

At last, to White’s relief, the image faded to black; the softscreen filled up with some kind of cartoon.

Jackie, awkwardly, offered to put him up for the night. It was a genuine offer but not exactly heartfelt; he found it easy to turn down. He would take a cab back into the city and find a hotel, fly home tomorrow.

When the cab came she walked him to the door; he emerged info the fresh sunlight.

He said, “I got a feeling I wasted my time here.”

“No,” she said, distracted. Then she seemed to be trying to make more of an effort. She put her hand on his arm; her fingers were light, as fragile as dried twigs. “No. I’m sorry you feel that. I’m grateful you came. I know you were trying to help.”

“In my old fart way.”

“I didn’t mean that.”

“Sure you did.”

A shadow drifted across them, like a cloud. Together, they looked up, White shielding his rheumy eyes against the low afternoon sunlight.

It was an aerostat: a filmy bubble a mile wide, a geodesic sphere overlain by a translucent film that caught the sunlight, like a huge soap bubble. The shell, buoyed up by the heated air inside, was tinged with the green and yellow of crops, growing in the rich high-altitude light. And the base trailed what looked like spiny tentacles; they were electrostatic chargers, generating and scattering ozone. White could just make out the huge Boeing logo, and the ocean-blue flag of New Columbia, painted on the side.

To White, it was just another fix of disorientation. The whole floating factory-farm looked like some huge jellyfish: an alien invader, maybe, drifting through the tall blue sky of Earth.

Jackie looked up at him, her eyes empty, the tattoo scars on her cheeks a washed-out pink in the sunlight. “I lost my mother years ago. Or maybe she lost me. The fact that she’s still alive up there, floating around half-way to Jupiter in some metal coffin, is just—” She hunted for the word. “Theoretical.”

He tried to think of something to say, some way to get out of this situation.

You’re too old, Marcus, just too damn old.

Day 1181

Alone in the humming calm of the flight deck and with her feet padding at the Teflon sheet — with all the lights subdued save for the small instrument glows, surrounded by the soft sounds of her mother’s voice, her own breathing and the high-pitched whir of the pumps — Nicola Mott stared upwards at the moons of Jupiter.

The crop yields continued to fall, and the transmission of mutations to successive generations was rising. Some plants, like the strawberries, refused to flower altogether. Rosenberg had talked about the reasons for this — inappropriate cell structures, poor fluid transmission — but Mott just tuned him out. The science really didn’t matter right now; in a sense, it never had.

They just had to find solutions with their available resources. Ways to survive.

So they were improvising. Rosenberg had designed a new plant growth unit to work in the centrifuge arm, where the plants could be subjected to a high percentage of a G for most of each day. That meant transferring some of the farm’s equipment — lamps, the air blower system, racks and nutrient baths and reservoirs — into the cramped arm cabin.

It was a long and difficult job, to which they were all having to contribute, under Rosenberg’s reluctant supervision. It wasn’t going to be a complete answer; the growing area inside the arm would be nothing like sufficient to fulfil their needs. And the arm wasn’t shielded from radiation so well as the farm itself. But Rosenberg’s hope was that stronger growths in the arm, coupled with at least some provision from the original farm, would close the gap in their requirements, before they started to go hungry.

The biggest drawback was the loss of the centrifuge for the crew.

They had reinstalled the exercise cycle, up on the flight deck, where there was still a little room. But not the treadmill.

That pissed Nicola Mott. It had been proven, all the way back to Skylab, that a treadmill was a much better way of exercising a range of muscle groups than a cycle. In her opinion it was just another example of the crew’s collective laziness and incompetence, which would lead them all, ultimately, into disaster.

Anyway, she had got on with devising her own solution.

She improvised a treadmill. It was just a slippery sheet of Teflon that she bolted to the floor of the flight deck, behind the pilot’s seat. She could balance herself with a hand on the seat in front of her, and just walk along, her feet slithering on the slippery pad. She wore socks, so her feet could slide more easily. It wasn’t as effective as the real thing; too often she stubbed a toe on the bolts that held the Teflon in place, and because she couldn’t vary the resistance, generally it was muscle fatigue that stopped her working. But she found if she worked at it long enough her calves, tendons and toes got a real workout.