The Neutral Buoyancy Space Simulator was built in Huntsville, Alabama in 1955. Located at the George C. Marshall Space Flight Center it was built to imulate a zero-gravity environment. The Neutral Buoyancy Space Simulator was designed by the U.S. Army and was an important factor for the American manned space program and NASA. In 1985 it became a National Historic Landmark.
source: Wiki- NASA
