“Here we go again,” Jones said. His Tennessee twang was calm and relaxed — as if he does this every day.

Well, Chuck Jones could playact his calmness all he liked; but even he had to be wound up tight as a watch spring, Dana thought, because the most important moment in the flight was approaching. The third stage of the stack was not the old reliable S-IVB which had carried the Moon missions to Earth orbit and beyond; it was an S-NB, with the first operational NERVA engine. And the damn thing was going to have to work to get them to orbit, Dana knew, or they were going to be flying across the Atlantic to a hard landing in the goddamn Sahara.

York called up: “Apollo, Houston, you are go for orbit. You are go for orbit.”

For long seconds the spacecraft soared, without acceleration; and then, at last, Dana was kicked in the back.

“She’s lit,” Chuck Jones breathed. “How about that. We’re flying a goddamn nuke.”

The NERVA burn was nothing like so jarring as the second-stage ignition six minutes earlier; the ride was crisp and rattly, with just two hundred thousand pounds of thrust pressing a full G into his back.

And then Earthlight strobed past Dana’s window. The Apollo had dipped toward the ground.

He was thrown forward against his restraints, the breath knocked out of him. My God. What now?

The nose of the craft pitched up again. Metal groaned, and Earth’s brilliant face swooped past his window. His helmet thumped against the sparse metal frame of his couch. Blue light flashed over his visor.

Chuck Jones’s voice was dry. “We’re riding a bronco here, Houston. Please advise.”

“Booster, Flight. Tell me what you’ve got.”

To Donnelly, it looked as if the little Saturn icon on the plot board was drunk, as it wandered crazily around its programmed trajectory. A dozen voices jabbered in Donnelly’s ear at once; he listened to them all, somehow simultaneously, trying to piece together what was happening.

But the most important voice wasn’t there. Mike Conlig wasn’t speaking to him.

“Booster, Flight,” he repeated. “You got anything you want to say?”

Even without Conlig he could follow the bones of what was happening. The S-NB seemed to be working nominally, in fact. The pitching must be due to leftover problems from the pogoing. The vehicle had been tipped up too high when staging came. So when the S-NB cut in, it found itself pointing too far into space. It had gimbaled its nuclear engine, and tried to point its way toward the center of the Earth. For long seconds the guidance system battled with the limits of gimbal on the engine. And then the S-NB seemed to figure that its path had gotten too low, so it pitched itself up again…