Skylab, a two-story, Earth-orbiting laboratory, was launched on May 14, 1973. For NASA’s first space station, Marshall Space Flight Center’s Neutral Buoyancy Simulator took underwater training to a new level. In Homesteading Space: The Skylab Story, authors David Hitt, Owen Garriott, and Joe Kerwin wrote, “The Neutral Buoyancy Simulator was a working facility. The theory had been proven and now was being put into practice.”
The NBL could fit spacecraft much larger than the capsules of the 1960s. The authors quoted tank manager Jim Splawn: “We sort of had the vision of building a facility large enough to accommodate some pretty large mock-ups of hardware, and it really proved out to be very, very beneficial.”
Shown here is astronaut Ed Gibson (a crewmember of the Skylab 4 mission), during EVA training at the Apollo Telescope Mount (ATM) mockup in November 1970. At that time, the ATM was the most powerful observatory put into orbit.