The Space Shuttle is a partially reuseable spacecraft. It was developed and flown by NASA or the National Aeruonautics and Space Administration from 1981 to 2011 flying a total of 135 missions carrying a total of 833 astronauts to space, many of which went more than once. In total six orbiters were built, one of which was not capable of orbital flight but was used in landing tests in the development phase of the shuttle, in the history of the program two of the orbiters were lost in flight.