The first Space Shuttle, Enterprise (OV-101), was a test vehicle designed to operate in the atmosphere; it was not equipped for spaceflight. The Enterprise was rolled out at Rockwell International's assembly facility in Palmdale, California in 1976. In 1977, it entered service at NASA's Dryden Flight Research Center, Edwards Air Force Base, for a nine-month-long approach and landing test program. The main role of the test vehicle Enterprise was to check the Shuttle's flight characteristics and performance. The vehicle was flown atop the Boeing 747 Shuttle carrier aircraft and also released for piloted free-flights and landings to check out all systems and performance characteristics. This test program was a necessary prelude to the first orbital flight by the Space Shuttle Columbia in 1981. In 1985, NASA transferred Enterprise to the Smithsonian Institution's National Air and Space Museum.