The orbital workshop is the largest component of Skylab, America's first space station. It houses the living quarters, work and storage areas, research equipment, and most of the supplies needed to support a succession of three-man crews. Two complete Skylab space stations were manufactured and equipped for flight, and one was launched into Earth orbit in May 1973. After the Skylab program was canceled as effort shifted to Space Shuttle development, NASA transferred the backup Skylab to the National Air and Space Museum in 1975. On display in the Museum's Space Hall since 1976, the orbital workshop has been slightly modified to permit viewers to walk through the living quarters.