OSO 3 (Orbiting Solar Observatory 3), or Third Orbiting Solar ObservatoryNASA GSFC X-ray Astronomy Satellites and Missions GSFC HEASARC "The Third Orbiting Solar Observatory (OSO-3)" (known as OSO E2 before launch) was launched on March 8, 1967, into a nearly circular orbit of mean altitude 550 km, inclined at 33° to the equatorial plane. Its on-board tape recorder failed on June 28, 1968, allowing only the acquisition of sparse real-time data during station passes thereafter; the last data were received on November 10, 1969. OSO 3 reentered the Earth's atmosphere and burned up on April 4, 1982.
Like all of the early Orbiting Solar Observatory (OSO) series satellites, it had two major segments: one, the "Sail", was stabilized to face the Sun, and carried both solar panels and Sun-pointing experiments for solar physics. The other, "Wheel" section, rotated to provide overall gyroscopic stability and also carried sky-scanning instruments that swept the sky as the wheel turned, approximately every 2 seconds. OSO-8, the final spacecraft in this series, had 3-axis pointing.
Instrumentation
+ Experiments on board OSO 3 Name Target Principal Investigator High Energy Gamma Ray (> 50 MeV) anti-solar Kraushaar, W. L., Massachusetts Institute of Technology Cosmic Ray Spectrum Detector and Gamma Ray Analyzer Sun, all-sky Kaplon, Morton F, University of Rochester Directional Radiometer Experiment Earth Neel, Carr B Jr, NASA Ames Research Center Earth Albedo (0.32- to 0.78-μm) Earth Neel, Carr B Jr, NASA Ames Research Center Solar EUV Spectrometer 0.1 to 40.0 nm Sun Neupert, Werner M, NASA Goddard Space Flight Center 0.8- to 1.2-nm Solar X-Ray Ion Chamber Sun Teske, Richard G, University of Michigan Solar and Celestial Gamma-Ray Telescope (7.7 to 200 keV) Sun, all-sky Laurence E. Peterson University of California, San Diego Thermal Radiation Emissivity near-Earth space environment Neel, Carr B Jr, NASA Ames Research Center Extreme Ultraviolet Spectrometer Sun Hinteregger, Hans E, Phillips Laboratory
The Sail carried a hard X-ray experiment from UCSD, with a single thin NaI(Tl) scintillation crystal plus phototube enclosed in a howitzer-shaped CsI(Tl) anti-coincidence shield. The energy resolution was 45% at 30 keV. The instrument operated from 7.7 to 210 keV with 6 channels. The Principal Investigator (PI) was Prof. Laurence E. Peterson of UCSD. Also in the wheel was a cosmic gamma-ray (>50 MeV) sky survey instrument contributed by MIT, with PI Prof. William L. Kraushaar.
Scientific results OSO-3 obtained extensive hard X-ray observations of solar flares, the cosmic diffuse X-ray background, and multiple observations of Scorpius X-1, the first observation of an extrasolar X-ray source by an observatory satellite.Pelling, R. M. 1971, Ph.D. dissertation thesis, University of California at San Diego
The MIT gamma-ray instrument obtained the first identification of high-energy cosmic gamma rays emanating from both galactic and extra-galactic sources.
See also
Orbiting Solar Observatory X-ray astronomy
References
External links The content of this article was adapted and expanded from NASA's HEASARC: Observatories OSO 3 and NASA's National Space Science Data Center: OSO 3 (Public Domain)