Hubble Space Telescope
The Hubble Space Telescope (HST) is an Earth-orbiting telescope with a 2.4-m diameter mirror, named after the astronomer Edwin Hubble. It is operational at ultraviolet, optical and infrared wavebands. When first launched by the Space Shuttle 'Discovery' in 1990, it provided unprecedented spatial resolution due to its position above the Earth's atmosphere, observing through which results in diffraction-limited seeing for non-adaptive optics ground-based telescopes at optical and infrared wavelengths. Cosmic UV radiation is blocked by the Earth's atmosphere meaning ground-based observing in this band is not possible.
The instruments onboard the HST include the Wide Field Planetary Camera 2 (WFPC2; to be replaced by the Wide Field Camera 3 in 2008), the Space Telescope Imaging Spectrograph (STIS), the Near Infrared Camera and Multi-Object Spectrometer (NICMOS), the Cosmic Origins Spectrograph (COS, to be installed in 2008) and the Advanced Camera for Surveys (ACS).
The HST is a joint programme between ESA (European Space Agency) and NASA (National Aeronautics and Space Administration) and science operations are co-ordinated by the Space Telescope Science Institute (STScI) in Baltimore, Maryland, USA. It has been maintained via 'on-orbit' servicing, whereby every 3 years a Space Shuttle mission is sent to repair equipment and install new instruments. The final servicing mission is planned for August 2008. The HST will be replaced by the next-generation James Webb Space Telescope, which is primed for observing at long-wavelength optical to mid-IR wavebands and is scheduled to launch in 2013.
