On September 17, 1976, NASA publicly unveils its first space shuttle, the Enterprise.
Although Enterprise never flew in space, it was used to test critical phases of shuttle preparations and landings.
Columbia was the first shuttle to fly into orbit. Its first four missions were test flights to show that the shuttle design was sound.
Columbia and its seven astronauts were lost Feb. 1, 2003, when it broke apart during re-entry on its 28th mission.
Challenger, the second operational shuttle made its first flight on April 4, 1983. Challenger was named after the British Navy's research vessel HMS Challenger that sailed the Atlantic and Pacific oceans during the 1870s.
Challenger hosted missions that saw astronauts take the first-ever spacewalks with jet packs. Challenger and its seven astronauts were lost Jan. 28, 1986, when a seal on one of its boosters failed.
Discovery has flown more than any other shuttle with 39 total missions, the first flight occurring in August 1984.
Discovery deployed NASA’s Hubble Space Telescope and was the first space shuttle retired from NASA’s fleet.
Endeavour was named by students in elementary and secondary schools across the nation.
In May of 1992, three spacewalking astronauts made the unprecedented effort to grab an orbiting satellite with their gloved hands and pull it into Endeavour’s cargo bay. Endeavour was the second shuttle to retire after its successful 25th mission.
Atlantis was the fourth operational shuttle and made its first flight on Oct. 3, 1985.
Atlantis' final flight on July 2011 was also the last for the Space Shuttle Program.