expensive process than previously realized, involving the dismantling of the orbiter and the return of various structural sections to subcontractors across the country. As a consequence, NASA made the decision to convert an incomplete Structural Test Article, numbered STA-099, which had been built to undergo a variety of stress tests, into a fully flight-worthy orbiter, which became . Preparation for STS-1 Following the MGVT program and with the decision to not use Enterprise for orbital missions, it was ferried to Kennedy Space Center on April 10, 1979. By June 1979, it was again mated with an external tank and solid rocket boosters (known as a boilerplate configuration) and tested in a launch configuration at KSC Launch Complex 39A for a series of fit checks of the facilities there. After this period, Enterprise was returned to NASA's Dryden Flight Research Facility in September 1981. In 1983 and 1984, Enterprise underwent an international tour visiting France, West Germany, Italy, the United Kingdom, and Canada. Enterprise also visited California, Alabama, and Louisiana (while visiting the 1984 Louisiana World Exposition). It was also used to fit-check the never-used shuttle launch pad at Vandenberg AFB, California. On November 18, 1985, Enterprise was ferried to Washington, D.C., where it became property of the Smithsonian Institution and was stored in the National Air and Space Museum's hangar at Dulles International Airport. Post-Challenger After the Challenger disaster, NASA considered using Enterprise as a replacement. Refitting the shuttle with all of the necessary equipment for it to be used in space was considered, but NASA decided to use spares constructed at the same time as and to build . Post-Columbia In 2003 after the breakup of during re-entry, the Columbia Accident Investigation Board conducted tests at Southwest Research Institute, which used an air cannon to shoot foam blocks of similar size, mass and speed to that which struck Columbia at a test structure which mechanically replicated the orbiter wing leading edge. They removed a section of fiberglass leading edge from Enterprise wing to perform analysis of the material and attached it to the test structure, then shot a foam block at it. While the leading edge was not broken as a result of the test, which took place on May 29, 2003, the impact was enough to permanently deform a seal and leave a thin gap long. Since the strength of the reinforced carbon–carbon (RCC) on Columbia is "substantially