OSO-8 turns out great—Hughes News January 19, 1979 Transcribed by Faith Macpherson

Sun studies ‘oh so’ good

The HAC-built Orbiting Solar Observatory (OSO-8) satellite has been turned off after supplying what NASA scientists consider the most accurate data on the Sun and its functions for three years.

The last of the “sunshine” satellites, which started investigation of the Earth’s nearest star with OSO-1 in 1962, was designed to last one year. It was launched June 21, 1975, from Cape Canaveral, FL.

The spacecraft, designed and built by Space and Communications Group, received high praise for its operations and data returned from NASA officials.

NASA indicated that the Sun-pointed experiments aboard OSO-8 obtained the most accurate observations of the solar chromospheres, the layer of the solar atmosphere just above the relatively cool visible surface of the Sun, and of the transition zone between the chromosphere and the Sun’s extremely hot corona.

“The OSO series has provided a vast wealth of scientific information about the Sun and other celestial objects,” said Roger Thomas, NASA Goddard Space Flight Center OSO-8 project scientist.

“Each of the satellites carried different and succeedingly more accurate instruments to investigate new aspects of the Sun,” he continued.

“The lessons we have learned from 16 years of the OSO mission have been instrumental in the development of new experiments for future studies of the Sun.”

HAC Program Manager Jim Meyer said although OSO-8 was a complex spacecraft, there was little surprise that it continued to work for three years.

OSO-8 carried eight experiments. Two scanned the Sun’s chromosphere to study ultraviolet radiation. The other six made solar and celestial x-ray measurements of the extremely hot and high energy particles in space.

The studies were conducted from OSO-8 as it orbited the Earth from 345 miles up. At this distance, all experiments could be conducted without interference from the Earth’s atmosphere.

NASA Goddard was able to aim OSO-8’s on-board instruments at the Sun with the pointing accuracy of one arc-second, which is one three-hundred-and-sixtieth of a degree. This stability made it possible for the instruments to scan 450-mile wide swaths of the Sun.

The OSO-8 scientific instruments were silenced during the satellite’s 18,072 orbit by a planned radio command sent from Goddard through NASA’s Orroral, Australia, tracking station.

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