Space Shuttle orbiter its maiden flight in 1977. An unpowered glider, it was carried by a modified Boeing 747 airliner called the Shuttle Carrier Aircraft and released for a series of atmospheric test flights and landings. "Enterprise" was partially disassembled and retired after completion of critical testing. The remaining orbiters were fully operational spacecraft, and were launched vertically as part of the Space Shuttle stack. "Columbia" was the first space-worthy orbiter, and made its inaugural flight in 1981. "Challenger", "Discovery", and "Atlantis" followed in 1983, 1984 and 1985 respectively. In 1986, "Challenger" was destroyed in an accident shortly after launch. "Endeavour" was built
Space Shuttle in an emergency, the orbiter was loaded atop the Shuttle Carrier Aircraft, a modified 747, for transport back to the Kennedy Space Center, landing at the Shuttle Landing Facility. Once at the Shuttle Landing Facility, the orbiter was then towed along a tow-way and access roads normally used by tour buses and KSC employees to the Orbiter Processing Facility where it began a months-long preparation process for the next mission. NASA preferred Space Shuttle landings to be at Kennedy Space Center. If weather conditions made landing there unfavorable, the Shuttle could delay its landing until conditions are favorable, touch down