Space Shuttle Discovery (Orbiter Vehicle Designation: OV-103) is one of the retired orbiters of the Space Shuttle program of NASA, the space agency of the United States, and was operational from its maiden flight, STS-41-D on August 30, 1984, until its final landing during STS-133 on March 9, 2011. Discovery has flown more than any other spacecraft having completed 39 successful missions in over 27 years of service. In 1984, Discovery became the third operational orbiter following Columbia and Challenger, and made its final touchdown at Kennedy Space Center on March 9, 2011 at 10:57:17 CST,having spent a cumulative total of almost a full year in space. Discovery has performed both research and International Space Station (ISS) assembly missions. Discovery also flew the Hubble Space Telescope into orbit. Discovery was the first operational shuttle to be retired, followed by Endeavour and then Atlantis.