Space Shuttle Discovery completed its final mission, STS133 (the 39th), to the International Space Station (ISS), delivering the Permanent Multipurpose Module, Express Logistics Carrier 4, and the Italian Leonardo module. This was followed by a mission of Endeavour (the 25th), one of Atlantis (the 33rd), and then, in July 2011, the Space Shuttle (STS) program concluded. The other shuttles that flew were Enterprise (test vehicle: 5 flights), Columbia (28 flights), and Challenger (10 flights), for a total of 135 flights (including the very first, in-atmosphere flights).
