Hubble Space Telescope

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© Hubblesite.

When NASA launched the Hubble Space Telescope into an orbit about 600 kilometers above Earth in April 1990, astronomers anticipated a cornucopia of new observations. But, within a few weeks, a serious problem emerged: The telescope's primary mirror had been precisely figured, but to the wrong shape. Fortunately, STScI engineer Jim Crocker devised a clever correction inspired by the folding spray head of the shower at the Hoyacker Hof in Garching, Germany. His plan involved adding two small new mirrors that unfolded into the light path and corrected for the telescope's main mirror. In December 1993, a team of astronauts aboard the Space Shuttle installed the "corrective optics space telescope axial replacement" package. The fix worked perfectly as a stopgap, and all the instruments brought up to HST since then have had their own corrections built in.

A decade after the successful repair, the HST faced another crisis. Sean O'Keefe, NASA's administrator at the time, canceled the final servicing mission to the telescope, scheduled for early 2005, asserting that the mission involved too much risk for the astronauts. However, astronomers were not willing to abandon one of NASA's most productive scientific satellites without a fight. They mounted a campaign that persuaded O'Keefe's successor, Michael Griffin, to reschedule the mission. Carried out in May 2009, it left the Hubble in good health. Astronomers hope that HST will be pouring out valuable data on cosmic questions for many years to come. (Unit: 11)