Which space shuttle completed the most orbital missions?

Discovery completed the most orbital missions of any space shuttle, flying 39 times between 1984 and 2011. Its final mission was STS-133, which landed on March 9, 2011, after delivering equipment and the Permanent Multipurpose Module to the International Space Station.

Discovery was the third operational shuttle to enter service. During its 27-year career, it deployed the Hubble Space Telescope, carried the Ulysses probe toward the Sun, visited the Russian Mir station, and flew 13 missions connected with International Space Station assembly and resupply.

It also flew both post-accident Return to Flight missions: STS-26 after the Challenger disaster and STS-114 after the Columbia disaster. Discovery carried John Glenn back into orbit in 1998, making him the oldest person to fly in space at that time.

Discovery’s 39 missions exceeded Atlantis’s 33, Endeavour’s 25, Columbia’s 28, and Challenger’s 10. After retirement, Discovery became part of the Smithsonian’s National Air and Space Museum collection and is displayed at the Udvar-Hazy Center in Virginia.