Space Shuttle Program

NASA's Space Shuttle Program developed and operated a reusable crewed orbital transportation system from its early development and atmospheric tests through 135 orbital missions between 1981 and 2011. The fleet launched satellites and scientific payloads, supported Spacelab research, retrieved and repaired spacecraft, visited Mir, and carried much of the hardware and workforce for International Space Station assembly. The program combined winged orbiters, an expendable external tank, and recoverable solid rocket boosters. Challenger and Columbia were lost with their crews, prompting major investigations and changes to flight safety, hardware, inspection, and operations before the fleet's retirement.