Hubble Space Telescope (HST) Description
The Hubble Space Telescope (HST) is a 25,500-lb (11,600kg) earth-orbiting astronomical observatory, a joint project of NASA and the European Space Agency (ESA). Three major sections make up the HST: the Optical Telescope Assembly, the Scientific Instruments, and the Support Systems Module. The telescope is a Cassegrain reflector with a 94.5-inch (2.4m) primary mirror and a 12-inch (0.34m) secondary mirror comprising an f/24–Ritchey-Chretien optical system with a 2.8 arc-minute field of view. Its instruments are modular and replaceable. Those currently installed are sensitive to visible and ultraviolet light; the next generation of instruments is being engineered now, to be installed during a future Space Shuttle mission. The Support Systems Module provides the systems necessary for operating the observatory: power, command, telemetry, attitude control, pointing, data storage, and telecommunications.