Through the pain, Priest felt a kind of security settle over him. As best he could tell, this was about the point in the reentry sequence when the automatics were supposed to kick in anyway. Apollo-N was back on its flight plan, for the first time since the NERVA core had blown.

“You got that pre-advisory data ready yet, Retro?”

“Not yet, Flight.”

It was getting damned late. Something is wrong. What isn’t he telling me?

Rolf Donnelly had thought that the most dangerous moment in this reentry would be when the Command Module dug deep into the atmosphere, when it would be totally reliant on its heat shield. And if that shield had been cracked during the explosion, the craft was going to split open and burn like a meteor. He couldn’t do anything about that; it was a question of waiting and hoping.

As yet they’d barely grazed the top of the atmosphere. But, then, totally out of the blue, he feared already he was about to lose the Command Module.

The controller called Retro, down in the Trench, was in charge of controlling the Command Module’s reentry angle. Just before the Service Module separation, Retro had been telling Donnelly that Apollo-N’s angle of attack was right in the middle of the entry corridor. It could hardly have been better, in fact. And that meant that the pre-advisory data Retro had prepared earlier was still valid. The pre-advisory data contained the final vector that would control the spacecraft’s degree of lift while it fought the atmosphere.

But Retro still had to feed the final pre-advisory to the Command Module’s onboard computers. And then, minutes before the atmosphere started to bite, Donnelly could hear Retro arguing with FIDO, the flight dynamics controller, who was passing Retro updated predictions on the spacecraft’s trajectory.

Retro blurted: “I don’t believe you, FIDO!”

Donnelly felt acid spurt into his stomach. “Clarify, Retro. You want to tell me what’s going on over there?”

“The trajectory is shallowing, Flight. We’re up by point three one degrees.”

Still within the corridor. But that was a heck of a lot of shallowing at this point. And if the shallowing continued, Retro was going to have to revise the pre-advisory data. “You have any idea what’s happening up there, Retro?”

“No idea, Flight.” There was tension in the voice, and Donnelly could see Retro peering over the shoulder of FIDO, next to him, trying to get the latest trajectory updates.

Was the trajectory going to shallow any more? That depended on the cause. If, say, one of the attitude thrusters was stuck open, the shallowing would continue. But if propellant or coolant was boiling off from some flaw in the hull, then the cause might dwindle and the shallowing stop.

The trouble was, nobody knew. None of them was sure about the extent of the damage the Command Module had suffered in the core rupture.