The Hubble Telescope was carried into orbit on this day, April 24th, back in
1990, which makes it 19 years old. Now it can finally legally drink alcohol in
Ontario!
The Hubble Space Telescope (HST) is a space telescope
that was carried into orbit by
the Space Shuttle Discovery in April 1990. It is named after the
American astronomer Edwin Hubble. Although not
the first space telescope, the Hubble is one of the largest and most versatile,
and is well-known as both a vital research tool and a public relations boon for
astronomy. 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.[3]
Space telescopes were proposed as early as 1923. The 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 position outside the 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.
The Hubble is the only telescope ever designed to be serviced in space by
astronauts. To date, there have been four servicing missions. Servicing Mission
1 took place in December 1993 when Hubble's imaging flaw was corrected.
Servicing missions 2, 3A, and 3B repaired various sub-systems and replaced many
of the observing instruments with more modern and capable versions. However,
following the 2003 Columbia Space Shuttle
disaster, the fifth servicing mission was canceled on safety grounds. After
spirited public
discussion, NASA reconsidered this decision, and administrator Mike Griffin gave
the green light for one final Hubble servicing mission. This was planned for
October 2008, but in September 2008, another key component failed.[4] The
servicing mission has been postponed until May 2009[5] to allow this
unit to be replaced as well.
The planned repairs to the Hubble should allow the telescope to function
until at least 2013, when its successor, the James
Webb Space Telescope (JWST), is due to be launched. The JWST will be far
superior to Hubble for many astronomical research programs, but will only
observe in infrared, so it would
complement (not replace) Hubble's ability to observe in the visible and ultraviolet parts of the
spectrum.
