Early large-scale neutral buoyancy training for astronauts

NASA's Neutral Buoyancy Simulator (NBS) at the Manned Spacecraft Center (later Johnson Space Center) in Houston was constructed in the mid-1960s and provided one of the earliest large-scale underwater facilities used by U.S. astronauts to rehearse weightless extravehicular activities. The NBS was used during the Apollo era to practice procedures that would later be performed on the lunar surface and in spacewalks, establishing neutral-buoyancy techniques that remain central to EVA training. The facility at JSC preceded the later Neutral Buoyancy Laboratory and helped define underwater spaceflight training protocols.