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 program from the two destroyed orbiters. The Space Shuttle program was extended several times beyond its originally envisioned 15-year life span because of the delays in building the United States space station in low Earth orbit—a project which eventually evolved into the International Space Station. It was formally scheduled for mandatory retirement in 2010 in accord with the directives President George W. Bush issued on January 14, 2004 in his Vision for Space Exploration. A$2.5 billion spending provision allowing NASA to fly the Space Shuttle beyond its then-scheduled retirement in 2010 passed the Congress in April 2009, although neither NASA nor