Five flight-worthy orbiters were constructed for the program:
The Shuttle system consisted of three primary components that worked together for launch: The Space Shuttle
40 Years Ago: Space Shuttle Enterprise rolls to the Pad - NASA it completed 25 missions
: Built as a replacement for Challenger, it completed 25 missions, including the first service mission for Hubble. it flew 39 missions
: Flew the final mission of the program (STS-135) in July 2011.
: Known for carrying the first American woman and African American into space; destroyed 73 seconds after liftoff in 1986.
: The "workhorse" of the fleet, it flew 39 missions, including the launch of the Hubble Space Telescope.