The idea was that the empty S-IVB would be used as a space station shell, a Skylab, once it had reached orbit. The S-IVB and the Apollo carrying its crew would be launched separately, by Saturn IB boosters, the smaller, cheaper cousins of Saturn Vs. The astronauts would dock with the booster by nuzzling the nose of their Apollo against the docking adapter, and then enter through specially fitted airlocks. The crew would clean out the shell and settle down to live inside the big liquid hydrogen tank.

The sim wasn’t painted, or finished in any way. It all looked ungainly, ugly, evidently lashed up in haste.

The simulation supervisor’s voice sounded in his headset. “Good morning, Chuck, Adam.”

Good morning to you, asshole.

Bleeker turned and waved at one of the ubiquitous TV cameras.

The SimSup said, “I just want to review the basic parameters of the sim with you, before you start. Now, you know this isn’t an integrated sim.” Meaning they weren’t hooked up to Mission Control. “This is just a preliminary trial of the checklist we’re going to have to use when we fit out the workshop in orbit. Okay, let’s proceed.”

The divers nodded to Jones, and they guided him closer to the Apollo mockup. It was just an open cone, fitted to the docking adapter. The simulation was supposed to start at the moment at which the crew was moving into the workshop to configure it for habitation.

Their first job was to dismantle the docking assembly in Apollo’s nose and open up the tunnel to the workshop. That part, at least, should go smoothly, because that sort of docking was standard operating procedure on the Moon missions.

Jones heard Bleeker’s breath scratching as he hauled at the heavy docking-probe assembly. “Take it easy, kid. We’re being paid by the hour.”

Bleeker laughed, and his posture relaxed a little.

When they had the probe assembly loose, Bleeker passed it to a diver.

Bleeker moved ahead of Jones into the Multiple Docking Adapter. The adapter was a tight tunnel, lined with lockers. All the equipment for living quarters, clothes, food, experiments, and the rest was stored in the lockers during the launch; after they’d fitted out the hydrogen tank for habitation, Jones and Bleeker would have to return here, unpack the lockers, and move the equipment into the tank.

Bleeker passed on, into the hydrogen tank itself.

The metal walls of the tank opened out around him. It was pitch-dark, and Jones had the feeling that he was following Bleeker into a huge, forbidding metal cave. “Hold up, Adam; let’s throw a little light on the situation here.” Jones unclipped a portable light from his belt and fixed it to the fireman’s pole that passed along the axis of the tank.