April 24, 1990 – Space Shuttle DISCOVERY launches on the STS-31 mission, deploying the Edwin P. Hubble Space Telescope (HST) astronomical observatory.
Hubble was placed into the correct orbit, but had operational problems that caused imaging troubles. Fortunately, the Hubble Space Telescope was designed to be serviced while in space by NASA astronauts. A total of five Space Shuttle missions visited and repaired the Hubble between 1993 and 2009. Hubble is expected to stay in service until 2014, when it may be replaced by the James Webb Space Telescope (JWST) (which as of this writing, is expected to be launched in 2018).
Hubble has looked deeper into the universe than any other telescope, and has produced some of the most magnificent pictures ever taken in space.