She heard a faint, muffled bang; the cabin shuddered, rattling her against her restraints. Separation squibs had fired, pushing the exhausted solid boosters away from the main stack. She felt a dip in the thrust; but then the acceleration of the MS-IC’s central liquid boosters picked up again, and she was pressed back into her seat.

“Roger on the sep,” Young said.

“Smooth as glass, John.”

The solid boosters would be falling away like matchsticks, dribbling smoke and flames. The strap-on solid boosters were the most visible enhancement of the VB over the core Saturn V design; with their help the VB was capable of carrying twice the payload of the V to Earth orbit.

“Five thousand one hundred feet per second,” Stone said. “Thirty-three miles downrange.”

She glanced at the G-meter. Three times the force of gravity. It wasn’t comfortable, but she had endured a lot worse in the centrifuge.

Cool air played inside her helmet, bringing with it the smell of metal and plastic.

With the SRBs gone, the ride was a lot easier. Liquid motors were fundamentally smoother burners than solids. She could hear the mounting, steady roar of the MS-IC’s engines, the continuing purr of the Command Module’s equipment.

Everything was smooth, ticking, regular. Inside the cosy little cabin, it was like being inside a huge sewing machine. Whir, purr. Save for the press of the acceleration it was unreal: as if this was, after all, just another sim.

“Three minutes,” Stone said. “Altitude forty-three miles, downrange seventy miles.”

“Coming up on staging,” Gershon said. “Stand by for the train wreck.”

Right on schedule the first-stage engines shut down.

The acceleration vanished.

It was as if they were sitting in a catapult. She was thrown forward, toward the instrument panel, and slammed up against her restraints. The canvas straps hauled her back into her seat, and then she was shoved forward again.

The first-stage engines had compressed the whole stack like an accordion; when the engines cut, the accordion just stretched out and rebounded. It was incredibly violent.

Just like a train wreck, in fact. Another thing they didn’t tell me about in the sims.

She heard the clatter of explosive bolts, blowing away the dying MS-IC. And there were more bangs, thumps in her back transmitted through her couch: small ullage rockets, firing to settle the liquid oxygen and hydrogen in the huge second-stage tanks.

Vibration returned as the second-stage engines ignited, and she was shoved back into her seat.

There was a loud bang over her head, startling her, as if someone was hammering on the skin of the Command Module. Flame and smoke flared beyond her window.

“Tower,” Stone reported.

“Roger, tower.”

The emergency escape rocket had blown itself away, taking the conical cap over the Command Module with it. Daylight, startlingly brilliant, streamed into the cabin, lapping over their orange pressure suits, dimming the instruments.