During the program’s 30-year history, its five orbiters—
Columbia, Challenger, Discovery, Atlantis and Endeavour—
carried more than 350 people into space and flew more than
500 million miles, and shuttle crews conducted important
research, serviced the Hubble Space Telescope and helped
in the construction of the International Space Station, among
other activities.

NASA retired the shuttles to focus on a deep-space exploration
program that could one day send astronauts to asteroids and
Mars.