Aug. 12, 1999
Vol. 18 No. 20

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    [chandra launch] courtesy of NASA

    The Chandra X-ray Observatory was successfully deployed Friday, July 23, from the Space Shuttle Columbia’s cargo bay at 155 miles above the Earth.

    NASA successfully launches Chandra X-ray Observatory, prepares operations

    Successfully launched from the Kennedy Space Center in Florida on Friday, July 23, the Chandra X-ray Observatory has begun its expected five-year mission to collect X-ray images of violent occurrences, such as the death of stars and colliding galaxies, to help scientists understand the structure and evolution of the universe.

    Chandra, NASA’s most powerful X-ray telescope and its third Great Observatory, is named for the late Chicago astrophysicist Subrahmanyan Chandrasekhar, who won the 1983 Nobel Prize in physics. The other two Great Observatories, the Hubble Space Telescope and the Compton Gamma-ray Observatory, also were named for Chicago scientists.

    Chandra has been placed in a highly elliptical orbit, unlike the circular orbit of the Hubble Space Telescope. At its closest approach to Earth, Chandra will be at an altitude of about 6,200 miles. At its farthest, 87,000 miles, it will travel almost one-third of the way to the moon. Because of its elliptical orbit, the observatory will circle the Earth every 64 hours, carrying it far outside the belts of radiation that surround Earth. While harmless to life on Earth, this radiation can overwhelm the observatory’s sensitive instruments. The X-ray observatory will be outside this radiation long enough to take 55 hours of uninterrupted observations during each orbit.

    Continued activation and checks of the observatory’s instruments and operating systems have gone smoothly according to NASA status reports. Controllers continue to calibrate the Advanced Charge-Coupled Imaging Spectrometer, which records the position and energy of X-rays.

    Depressurization of the High-Resolution Camera optical cavity continues, and Earth sensor scans continue to be performed twice during each orbit of the observatory to update Chandra’s altitude reference for engine firings. The observatory is scheduled to begin collecting images at the end of August.