A 2.4-m reflector built by NASA and ESA, launched in 1990 April. It orbits at an altitude of about 600 km. An initial servicing mission by astronauts in 1993 December was necessary to install additional optics to correct the telescope's spherical aberration, caused by an error in manufacturing the main mirror. Subsequent servicing missions took place in 1997 February, 1999 December, and 2002 March, during which astronauts installed improved detectors and replaced the telescope's solar panels. After the fourth servicing mission, HST's scientific instruments consisted of the Advanced Camera for Surveys (ACS), the Wide Field and Planetary Camera 2 (WFPC2), the Near Infrared Camera and Multi–Object Spectrometer (NICMOS), and the Space Telescope Imaging Spectrograph (STIS). A fifth and final servicing mission took place in 2009 May, installing the Wide Field Camera 3 (WFC3) and the Cosmic Origins Spectrograph (COS), as well as repairing existing instruments. WFC3, which replaced WFPC2, can detect a wider range of wavelengths, from infrared to ultraviolet, than its predecessor. The servicing was intended to keep HST in operation at least until 2014. HST is controlled from NASA's Goddard Space Flight Center. The Space Telescope Science Institute plans the telescope's observing programme and collects its data.
http://www.nasa.gov/mission_pages/hubble/main/index.html Official mission website.
Subjects: Astronomy and Astrophysics.