Learn about the maintenance of the Hubble Space Telescope.
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The importance of the achievements of the mission STS 103 crew could not be overestimated. Long before mankind had the ability to go into space, astronomers dreamed of placing a telescope above earth’s obscuring atmosphere, an observatory in space was proposed in 1923 by the German scientist Hermann Oberth whose work inspired rocket pioneer, Dr. Wernher von Braun’s interest in space travel. Scientific instruments installed on early rockets, balloons and satellites in the late 1940s through to the early 1960s, produced enough exciting scientific revelations to hinted how much remained to be discovered. In 1962, just four years after NASA was established, a national academy of science study group recommended the development of a large space telescope as a long-range goal of the fledgeling space program. The recommendation was repeated by similar groups in 1965 and ’69. The first two successful NASA satellites designed for observing the stars were launched in 1968 and 1972. These orbiting astronomical observatories produced a wealth of information and support for an even larger, more powerful optical space telescope grew. The approval of the space shuttle, with its capacity for manned delivery and servicing of large payloads made the space telescope concept feasible. NASA selected a team of scientists in 1973 to establish the basic design of such a telescope and its instruments. An expanded group of 60 scientists from 38 institutions was formed to refine those recommendations in 1977. That same year, Congress authorized funding for the project. Construction and assembly of the space telescope was a painstaking process which spanned almost a decade. The precision ground mirror was completed in 1981 and the optical assembly was delivered for integration into the satellite in 1984. The science instruments were delivered for testing at NASA in 1983. Assembly of the entire spacecraft was completed in 1985. Launch of the Hubble Space Telescope was originally scheduled for 1986. It was delayed during the space shuttle redesign which followed the Challenger accident. Engineers used the interim period to subject the telescope to intensive testing and evaluation, assuring the greatest possible reliability. Deployed on April 25th, 1990, the Hubble space Telescope with a resolving power calculated to be 10 times better than any telescope on earth was poised to open a new era in astronomy. Within a few months, however, a flaw was discovered in Hubble’s main mirror which significantly reduced the telescope’s ability to focus. The focus in defect was due to spherical aberration, an optical distortion caused by an incorrectly shaped mirror. The mirror was too flat near the edge by about 1/50th the width of a human hair. Instead of being focused into a sharp point, light collected by the mirror was spread over a larger area in a fuzzy halo. Images of objects such as stars, planets and galaxies were blurred. However, on relatively bright objects, Hubble’s cameras were still able to provide images far superior to any telescope on the ground. Program and project management officials working with the scientific community developed a plan to take advantage of the telescope’s instruments but were not affected by the aberration, such as ultraviolet and spectrographic observations. During its first three years of operation, Hubble provided significant new information and discoveries about the universe, including astonishing images of supernova 1997-A and a disc of cold gas fueling a black hole. But that was all historical data for Foale and Nicollier as they completed the third longest space walk in hostory, behind only the eight-hour, 15 minute effort the previous day, payload commander Steve Smith and Grunsfeld and the eight-hour 29 minutes space walk by three Endeavor astronauts on STS-49 on its Intelsat rescue mission on May 1992. Join us on this program next time when we’ll continue on board the space shuttle Discovery with the crew of mission STS-1

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