The fuel pod came free. York stumbled backwards, her boots scuffing at the gumbo in an effort to keep upright. The cables helped her that time, giving her just enough leverage to keep from falling.

The fuel pod went tumbling to the surface, like a dropped relay baton.

Gershon lumbered across to her, his face framed by his visor. “Hey. You okay?”

“Sure. How’s the pod?”

They bent over the little metal cylinder, where it lay in the pink gravel. There was a hairline crack down one seam.

“How about that,” Gershon said. “We busted it. We nuked Mars.”

“Well, it was only a mock-up. Probably the real thing will be tougher.”

“Christ, I hope so.”

“Okay, guys,” the supervisor said. “Both your heart rates are showing a little high. That is definitely it for now. Take five. We’ll resume in an hour.”

Jorge Romero came barging into the simulation chamber. “Goddamn it,” he stormed. “You did it again, Natalie! You broke my damn SEP! And you were a half hour behind schedule!”

York, free of her cabling, was sitting on the Rover with her helmet on her lap, cradling a mug of coffee. She smiled at him. “Oh, take it easy, Jorge. It’s only a sim.”

Romero, small, purposeful, pink with anger, marched back and forth across the fake Martian surface, sending up little sprays of gravel. “But that’s three times out of the last three that my SEP implementation has been screwed up…”

Her training had been intense, the compressed schedule committing her and the others to eighteen hours a day in complex exercises like this, for long weeks at a stretch. She felt her patience drawing thin as Romero paced about. I don’t have time for these debates, Jorge. But she owed him an answer.

“Look,” she said to Romero, “I know how you feel. But you have to make allowances, Jorge. Out on a field trip, you can take as long as you want, days or weeks thinking over a sample if you need to. It’s not like that here. The Marswalks can last only a few hours each. They’ll be even more curtailed than the old Apollo moonwalks. So we have to plan out every step. These simulations are” — she waved a hand — “choreography. It’s a different way of working, for you and me. Real time, they call it.”

Romero was still pissed. “Goddamn it. I’m going to write a memo to Joe Muldoon. All these screwups. Those Flight Operations people just can’t be running the mission properly.”

“But that’s the point of the sim, Jorge. We’re supposed to break things.” She found a grin spreading across her face, but she suppressed it. “I’m sorry, Jorge. I do know how you feel. I sympathize.”

He glared at her. “Oh, you do? So you haven’t gone over to the operational camp altogether?”

She winced. “That’s not fair, damn it.”