The Space Shuttle started flying in 1981, but the US Congress failed to approve sufficient funds to make "Space Station Freedom" a reality. A fleet of four shuttles was built: "Columbia", "Challenger", "Discovery", and "Atlantis". A fifth shuttle, "Endeavour", was built to replace "Challenger", which was destroyed in an accident during launch that killed 7 astronauts on 28 January 1986. From 1983 to 1998, twenty-two Shuttle flights carried components for a European Space Agency sortie space station called Spacelab in the Shuttle payload bay.