The lamp sent glimmering light through the water along the length of the tank, to a wall at the far end that bulged inward toward him. That was the bulkhead between the hydrogen tank and the booster’s lox tank beyond. Helium pressurization spheres clung to the walls like big silver warts. Handrails and poles looped across the metal cave, and folded-up partitions and other bits of kit were stowed neatly against the walls of the tank. Too neatly. I wonder what those poor schmuckos will find when they meet this bird in real life, in orbit.

The Skylabs were just lash-ups, really, improvisation. But they would give NASA experience it needed of orbital operations and long-duration flights, before the real space station cans started flying later.

“Okay, guys,” the SimSup said. “As you know, in orbit the first job would be to check that the propellant lines are properly blocked. Today, we want you to skip over that and proceed straight to the assembly of the floor.”

“We’ve read the checklist,” Jones growled. “Come on, pal.” He shinned along the fireman’s pole, deeper into the tank.

Bleeker and Jones manhandled packs of floor panels away from their stowage against the tank walls. Their job was to fit a floor of aluminum grid across the width of the tank, maybe two-thirds of the way along its length. Putting the panels together would be like assembling a jigsaw puzzle, working toward the tank’s axis.

The two men worked their way around the perimeter of the tank. It was simple work, but slow, clumsy, and tiring; Jones found it hard to grip tools with his suited hands, and the water resisted every motion.

Divers had followed them into the tank. One of them had brought in an underwater TV camera, and was filming them.

The SimSup tried to cheer them up. “We appreciate your help here, guys. We’re well aware that you two are slated for other missions, and probably won’t even be the ones to carry this out for real anyway…”

I sure as hell hope not, Jones thought.

Chuck Jones was supposed to be going to the Moon. He was backup commander on Apollo 15, which, according to the basic framework of crew rotation, would give him his own mission three shots later, on Apollo 18.

But Congress had cut NASA’s budget for fiscal 1971, making it the leanest budget for nine years. And Nixon still hadn’t responded to the Space Task Group’s proposals for the future shape of the space program, although the word was he was leaning toward a Mars program of some kind, under Kennedy’s relentless public pressure.

Anyhow, NASA was going to need Saturn Vs to launch its Skylabs and space station modules and NERVA test flights. So, NASA was going to have to conserve Saturn V launches. The remaining lunar expeditions, Apollos 14 to 20, were going to be stretched out to six-month intervals…