Hubble Space Telescope data, while the Goddard Space Flight Center controls the spacecraft. Space telescopes were proposed as early as 1923. Hubble was funded in the 1970s, with a proposed launch in 1983, but the project was beset by technical delays, budget problems, and the "Challenger" disaster (1986). When finally launched in 1990, Hubble's main mirror was found to have spherical aberration, compromising the telescope's capabilities. The optics were corrected to their intended quality by a servicing mission in 1993. Hubble is the only telescope designed to be serviced in space by astronauts. After launch by in 1990, five subsequent Space Shuttle missions
Space Shuttle retirement Space Shuttle retirement The retirement of NASA's Space Shuttle fleet took place from March to July 2011. "Discovery" was the first of the three active space shuttles to be retired, completing its final mission on March 9, 2011; "Endeavour" did so on June 1. The final shuttle mission was completed with the landing of "Atlantis" on July 21, 2011, closing the 30-year Space Shuttle program. The Shuttle was presented to the public in 1972 as a "space truck" which would, among other things, be used to build a United States space station in low earth orbit in the early 1990s