HUBBLE SPACE TELESCOPE

HUBBLE SPACE TELESCOPE. Although astronomer Lyman Spitzer first suggested the idea of a space-based telescope in 1946, it was not until 24 April 1990 that one was placed in orbit around the earth. Named after the pioneering astronomer Edwin P. Hubble, it promised to overcome distortions caused by the earth's atmosphere. The forty-three-foot-long telescope could look seven times farther into space than the most powerful terrestrial observatories.

Computer problems in 1982 thwarted the $2 billion telescope's initial launching. Rescheduled for October 1986, its launch was again delayed by the tragedy in January 1986 that killed the crew of the space shuttle Challenger. Four years later, the Hubble Space Telescope fi-nally was lifted into space. Two months after the telescope was placed in orbit, scientists announced that its 94.5-inch primary mirror, polished to incredible smoothness, was flawed, resulting in blurred images. Ironically, the telescope was myopic. Investigation showed that engineers easily could have detected this problem prior to launch. Scientists had to delay or cancel experiments.

In December 1993 the crew of the space shuttle Endeavour fitted the telescope with corrective optics and

made other repairs. After this $629 million outer-space repair job, the telescope worked perfectly. It took detailed views of nebulae and star clusters. In October 1994 astronomers announced that data from the telescope showed that the universe was between eight billion and twelve billion years old, younger than earlier estimates by nearly half. Astronomers announced in January 1996 that the telescope was detecting hundreds of galaxies never before seen, which they speculated could be the most distant and oldest galaxies ever observed.

BIBLIOGRAPHY

Fischer, Daniel, and Hilmar Duerbeck. The Hubble: A New Window to the Universe. Translated by Helmut Jenkner and Douglas Duncan. New York: Copernicus, 1996.

Peterson, Carolyn Collins, and John C. Brandt. Hubble Vision: Further Adventures with the Hubble Space Telescope. 2d ed. New York: Cambridge University Press, 1998.

BrentSchondelmeyer/a. r.

See alsoChallenger Disaster ; Observatories, Astronomical ; Space Program .

Hubble Space Telescope (HST), the first large optical orbiting observatory . Built from 1978 to 1990 at a cost of $1.5 billion, the HST (named for astronomer E. P. Hubble ) was expected to provide the clearest view yet obtained of the universe from a position some 350 mi (560 km) above the earth. Using a Ritchey-Chrétien design that affords wider and flatter fields of view than traditional Cassegrain systems, the telescope has a 7.9-ft (2.4-m) primary mirror that can observe 24 hours a day (but usually observes less than 20% of the time) in a sky that is always clear and always has perfect seeing . Among the instruments are two high-resolution cameras and two spectrographs. The HST was launched from shuttle Atlantis in 1990. Initial tests taken after its launch showed that the primary mirror was astigmatic, and it was discovered that the mirror had been mistakenly ground to the wrong figure. The telescope was repaired by space shuttle astronauts in Dec., 1993; they replaced critical instruments and added corrective optics while in orbit. Subsequent servicing missions in 1997 and 1999 added capabilities to HST, which observes the universe at ultraviolet, near-ultraviolet, visible, and near-infrared wavelengths. In 2002 astronauts made repairs and improvements designed to enable the observatory to function for another decade, but in 2004 the power supply for the ultraviolet spectrograph failed. A final shuttle servicing mission in 2009 made additional repairs, replacements, and enhancements, including replacing the gyroscopes and the batteries and installing a new wide-field camera and a new ultraviolet spectrograph.

Hubble Space Telescope (HST) Optical telescope that was placed in Earth orbit by the space shuttle in 1990. Images transmitted back to Earth revealed that the telescope's main mirror was incorrectly shaped. A repair team corrected the fault in 1993, and it was again repaired in 1997. Hubble now produces acurate images of bodies that cannot be observed clearly by terrestrial telescopes due to atmospheric distortion.

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