The Space Shuttle Enterprise being worked on in the weight & balance hangar. The Enterprise, the first orbiter built, was not spaceflight rated and was used in 1977 to verify the landing, approach, and glide characteristics of the orbiters in the Approach and Landing Tests (ALT) at Edwards Air Force Base, California. It was also used for engineering fit-checks at the shuttle launch facilities. Following approach and landing tests in 1977 and its use as an engineering vehicle, Enterprise was donated to the National Air and Space Museum in Washington, D.C.