He nodded and sat down, with his tray. He had a vegetable lasagna, today’s healthy option; he picked up bits of pasta in his fork and brought them to his mouth. The daylight made his eyes an intense blue, impenetrable.

York tried to think of something to say.

“You busy?” she asked.

He grimaced around a mouthful of pasta. “What else? Busier than when I was on the flight, if you can believe that. They’ve got me in the sims more often than I can count.”

“I guess it shows how much—”

“ — you need me. I know, Natalie.”

“Look, Adam, I know how you must feel. Your training goes back to the Moon landings, for God’s sake. And to be overtaken by a rookie like me—”

“I’ve been studying space medicine,” he said unexpectedly. “In my spare time.”

She was startled by the non sequitur. Maybe it showed something about Adam’s state of mind. “Really? Why?”

He eyed her. “Wouldn’t you? I never took it seriously before. You know what I’ve found out? Legally, as a spaceflight crew, you’re a federal agency radiation worker. How about that. And you’re covered by Occupational Safety and Health Administration regulations, when it comes to radiation doses you receive in space.”

“So what does that mean? I’ll bet if we stuck to the rules, we’d never fly out of Earth orbit.”

He laughed. “Actually, that’s true. In low Earth orbit you’re protected, to some degree, by the magnetosphere. Outside, you’re exposed. But NASA does have an exemption, for ‘exceptional exploration missions.’ ”

“So they’ve covered their asses.”

“Yeah. Just like the Air Force. CYA.” He looked at her, his face unreadable. “You know, there is a lot of hazard out there, out of the shelter of the magnetosphere. You’ve got your solar particle events — solar flares, where you hide in your storm shelter — but there’s also the constant background radiation, cosmic rays from the galactic background. And women are—”

“Fifty percent more susceptible to radiation risk than men. I know, Adam,” she said.

His face was distant, inward looking. “You know, you can feel the difference up there. You’ll have to experience it, Natalie; I can’t describe it. You can feel the blood flowing through your heart valves, into your vessels. You come home with ‘chicken legs,’ as we call them. All that goes away. But then you’re hit by a kind of rapid aging… You know, Natalie, I’m not the only one.”

“The only what?”

“The only astronaut who’s come down like this. Nobody else on the active list has been grounded specifically because of radiation exposure, as far as I know. But some of the older guys, who flew in the 1960s, are showing up now with osteoporosis. Cancer. They’re turning up in their fifties and sixties, dying from risks you don’t find in the normal population.”