Jump to content


From Wikipedia, the free encyclopedia

The third Orbiting Solar Observatory, OSO 3, showing its "Sail" (upper), carrying solar experiments pointed at the Sun, and its rotating "Wheel" (lower), carrying two sky-scanning survey instruments: the UCSD hard X-ray experiment, and the MIT gamma-ray telescope
Mission typeSolar physics
COSPAR ID1967-020A Edit this at Wikidata
SATCAT no.02703Edit this on Wikidata
Mission duration2 years, 8 months
Spacecraft properties
Launch mass281 kilograms (619 lb)
Start of mission
Launch dateMarch 8, 1967, 16:19:00 (1967-03-08UTC16:19Z) UTC
RocketDelta C
Launch siteCape Canaveral LC-17A
End of mission
Last contactNovember 10, 1969 (1969-11-11)
Decay dateApril 4, 1982
Orbital parameters
Reference systemGeocentric
RegimeLow Earth
Perigee altitude534 kilometers (332 mi)
Apogee altitude564 kilometers (350 mi)
Inclination32.87 degrees
Period95.53 minutes
Mean motion15.07
EpochMay 8, 1967, 11:19:00 UTC[1]

OSO 3 (Orbiting Solar Observatory 3), or Third Orbiting Solar Observatory[2][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 the American 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.


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[edit]

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.[4][5][6][7]

The MIT gamma-ray instrument obtained the first identification of high-energy cosmic gamma rays emanating from both galactic and extra-galactic sources.[8]

See also[edit]


  1. ^ "NASA - NSSDCA - Spacecraft - Trajectory Details". nssdc.gsfc.nasa.gov. Retrieved May 2, 2018.
  2. ^ NASA GSFC X-ray Astronomy Satellites and Missions
  3. ^ [1] GSFC HEASARC "The Third Orbiting Solar Observatory (OSO-3)"
  4. ^ Peterson, Laurence E.; Jacobson, Allan S.; Pelling, R. M. (January 24, 1966). "Spectrum of Crab Nebula X Rays to 120 keV". Physical Review Letters. 16 (4). American Physical Society (APS): 142–144. doi:10.1103/physrevlett.16.142. hdl:2060/19660015394. ISSN 0031-9007.
  5. ^ Peterson, Laurence E.; Jacobson, Allan S. (1966). "The Spectrum of Scorpius XR-1 to 50 KEV". The Astrophysical Journal. 145. American Astronomical Society: 962. Bibcode:1966ApJ...145..962P. doi:10.1086/148848. ISSN 0004-637X.
  6. ^ Hudson, Hugh S.; Peterson, Laurence E.; Schwartz, Daniel A. (1970). "Simultaneous X-Ray and Optical Observations of SCO X-1 Flares". The Astrophysical Journal. 159. American Astronomical Society: L51. Bibcode:1970ApJ...159L..51H. doi:10.1086/180476. ISSN 0004-637X.
  7. ^ Pelling, R. M. 1971, Ph.D. dissertation thesis, University of California at San Diego
  8. ^ Kraushaar, W. L.; Clark, G. W.; Garmire, G. P.; Borken, R.; Higbie, P.; Leong, V.; Thorsos, T. (1972). "High-Energy Cosmic Gamma-Ray Observations from the OSO-3 Satellite". The Astrophysical Journal. 177. American Astronomical Society: 341-363. Bibcode:1972ApJ...177..341K. doi:10.1086/151713. ISSN 0004-637X.

External links[edit]

The content of this article was adapted and expanded from NASA's HEASARC: Observatories OSO 3 [2] and NASA's National Space Science Data Center: OSO 3 [3] (Public Domain)