The HST is a collaboration between NASA and the European Space Agency, and is one of NASA's Great
Observatories, along with
the Compton Gamma Ray Observatory, the Chandra X-ray Observatory, and the Spitzer Space Telescope.

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.

When finally launched in 1990, scientists found that the main mirror had been ground incorrectly,
severely compromising the telescope's capabilities. However, after a servicing mission in 1993,
the telescope was restored to its intended quality. Hubble's orbit outside the distortion of Earth's
atmosphere allows it to take extremely sharp images with almost no background light.

Hubble's Ultra Deep Field image, for instance, is the most detailed visible-light image ever made
of the universe's most distant objects.

Many Hubble observations have led to breakthroughs in astrophysics, such as accurately determining
the rate of expansion of the universe.

Hubble is the only telescope ever designed to be serviced in space by astronauts.

Four servicing missions were performed from 1993–2002, but the fifth was canceled on safety grounds
following the Space Shuttle Columbia disaster.

However, after spirited public discussion, NASA administrator Mike Griffin approved one final servicing
mission, completed in 2009.

The telescope is now expected to function until at least 2014, when its successor,
the James Webb Space Telescope (JWST), is due to be launched.

to deepen http://en.wikipedia.org/wiki/Hubble_Space_Telescope