OSO 3

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OSO 3
Oso3 small.gif
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 type Solar physics
Operator NASA
COSPAR ID 1967-020A
Mission duration 2 years, 8 months
Spacecraft properties
Manufacturer BBRC
Launch mass 281 kilograms (619 lb)
Start of mission
Launch date March 8, 1967, 16:19:00 (1967-03-08UTC16:19Z) UTC
Rocket Delta C
Launch site Cape Canaveral LC-17A
End of mission
Last contact November 10, 1969 (1969-11-11)
Decay date April 4, 1982
Orbital parameters
Reference system Geocentric
Regime Low Earth
Eccentricity 0.002164
Perigee 534.0 kilometers (331.8 mi)
Apogee 464.0 kilometers (288.3 mi)
Inclination 32.87 degrees
Period 95.53 minutes
Mean motion 15.07

OSO 3 (Orbiting Solar Observatory 3), or Third Orbiting Solar Observatory[1][2] (known as OSO C 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 sec.

Instrumentation[edit]

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 observations of solar flares, the cosmic diffuse X-ray background, and the observation of a single flare episode from Scorpius X-1, the first observation of an extrasolar X-ray source by an observatory satellite.[3][4][5]

The MIT gamma-ray instrument obtained the first identification of high-energy cosmic gamma rays emanating from both galactic and extra-galactic sources.[6]

See also[edit]

References[edit]

  1. ^ NASA GSFC X-ray Astronomy Satellites and Missions
  2. ^ [1] GSFC HEASARC "The Third Orbiting Solar Observatory (OSO-3)"
  3. ^ Pelling, R. M. 1971, Ph.D. dissertation thesis, University of California at San Diego,
  4. ^ Peterson et al 1966, Phys Rev Let 16, 142,
  5. ^ Peterson et al 1966, ApJ 145, 962.
  6. ^ Kraushaar, W. L., G. W. Clark, G. P. Garmire, R. Borken, P. Higbie, V. Leong, and T. Thorsos. 1972. High-energy cosmic gamma-ray observations from the OSO-3 satellite. ApJ 177, 341-363.

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)