Portal:Space exploration/Featured/November 2006

The Hubble Space Telescope (HST) is a telescope in orbit around the Earth. Its position outside the Earth's atmosphere allows it to take sharp optical images of very faint objects, and since its launch in 1990, it has become one of the most important telescopes in the history of astronomy. It has been responsible for many ground-breaking observations and has helped astronomers achieve a better understanding of many fundamental problems in astrophysics. Hubble's Ultra Deep Field is the deepest (most sensitive) astronomical optical image ever taken.

From its original conception in 1946 until its launch, the project to build a space telescope was beset by delays and budget problems. Immediately after its launch, it was found that the main mirror suffered from spherical aberration, severely compromising the telescope's capabilities. However, after a servicing mission in 1993, the telescope was restored to its planned quality and became a vital research tool as well as a public relations boon for astronomy. The HST is part of NASA's Great Observatories series, with the Compton Gamma Ray Observatory, the Chandra X-ray Observatory, and the Spitzer Space Telescope.

The future of Hubble is currently uncertain. Its stabilising gyroscopes need replacing, and without intervention to boost its orbit it will re-enter the Earth's atmosphere some time after 2010. Following the Columbia Space Shuttle disaster, NASA decided that a repair mission by astronauts would be unreasonably dangerous. The organization later reconsidered this position, but a final servicing mission still depends on the success of the Space Shuttle program in overcoming the design flaws which led to the Columbia disaster.

Hubble's successor telescope, the James Webb Space Telescope (JWST), is due to be launched in 2013 and will be far superior to Hubble for most astronomical research programs. However, the JWST will only observe in infrared, so it will not replace Hubble's ability to observe in the visible part of the spectrum.

Recently featured: Spacecraft propulsion – Saturn V