Space Shuttle Endeavour (Orbiter Vehicle Designation: OV-105) is a retired orbiter from NASA'sSpace Shuttle program and the fifth and final operational shuttle built. It embarked on its first mission, STS-49, in May 1992 and its 25th and final mission, STS-134, in May 2011. STS-134 was expected to be the final mission of the Space Shuttle program, but with the authorization of STS-135, Atlantis became the last shuttle to fly.