HST

Hubble Space Telescope (HST)

Cutaway of the NASA Hubble Space Telescope, revealing the Optical Telescope Assembly, the heart of …

(credit: Courtesy of Hughes Danbury Optical Systems, Inc.)

Most sophisticated optical observatory ever placed into orbit around Earth. Because it is above Earth's obscuring atmosphere, it can obtain images much brighter, clearer, and more detailed than ground-based telescopes can. Named for Edwin Hubble, it was built under NASA supervision and deployed on a 1990 space-shuttle mission. The reflector telescope's mirror optics gather light from celestial objects and direct it to an array of cameras and spectrographs (see spectroscopy). A defect in the primary mirror initially caused it to produce fuzzy images; in 1993 another shuttle mission corrected this and other problems. Subsequent missions to the HST have been for maintenance, repairs, and instrument upgrades.

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HST

(1) See Hubble Space Telescope.

(2) An earlier asymmetrical modem protocol from U.S. Robotics that included error control and compression and transmits from 4800 to 14400 bps in one direction and from 300 to 400 bps in the other. HST was the first reliable, high-speed modem protocol before the V.32bis and V.42 standards became widely used.