Space Shuttle Discovery (Orbiter Vehicle Designation: OV-103) is one of the three currently operational orbiters in the Space Shuttle fleet of NASA, the space agency of the United States. (The other two are Atlantis and Endeavour.) When first flown in 1984, Discovery became the third operational orbiter, and is now the oldest orbiter in service. Discovery has performed both research and International Space Station (ISS) assembly missions.
The spacecraft takes its name from four British ships of exploration named Discovery, primarily HMS Discovery, one of the ships commanded by Captain James Cook during his third and final major voyage, 1776–1779. Others include Henry Hudson's Discovery, which he used in 1610–1611 to search for a Northwest Passage; the HMS Discovery, one of the ships which took Captain George Nares' British Arctic Expedition of 1875–1876 to the North Pole; and RRS Discovery, a Royal Geographical Society research vessel which, under the command of Captain Robert Falcon Scott and Ernest Shackleton, was the main ship of the 1901–1904 "Discovery Expedition" to Antarctica which is still preserved as a museum.
Discovery was the shuttle that launched the Hubble Space Telescope. The second and third Hubble service missions were also conducted by Discovery. It has also launched the Ulysses probe and three TDRS satellites. Discovery has been chosen twice as the return to flight orbiter, first in 1988 as the return to flight orbiter after the 1986 Challenger disaster, and then for the twin return to flight missions in July 2005 and July 2006 after the 2003 Columbia disaster. Discovery also carried Project Mercury astronaut John Glenn, who was 77 at the time, back into space during STS-95 on October 29, 1998, making him the oldest human being to venture into space.
Had the planned STS-62-A mission from Vandenberg Air Force Base in 1986 for the United States Department of Defense gone ahead, Discovery would have flown it.