In its twenty-five-year history, NASA’s Space Shuttle program (officially called Space Transportation System or STS), has flown more than one hundred missions. It has enjoyed extraordinary success (such as the building of the International Space Station, and the servicing of the Hubble Space Telescope) but also suffered devastating failures. Two fatal missions (Challenger in 1986 and Columbia in 2003) left fourteen crew members dead. Space Shuttle missions resumed in 2005 with the successful Discovery “Return to Flight” mission.
