 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 |
| SATCATno. | 02703 |
| 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 CanaveralLC-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 altitude | 534 kilometers (332 mi) |
| Apogee altitude | 564 kilometers (350 mi) |
| Inclination | 32.87 degrees |
| Period | 95.53 minutes |
| Mean motion | 15.07 |
| Epoch | May 8, 1967, 11:19:00 UTC[1] |
OSO 3 (Orbiting Solar Observatory 3), orThird Orbiting Solar Observatory[2][3] (known asOSO 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 theEarth's atmosphere and burned up on April 4, 1982.
Like all of the earlyOrbiting 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.
| 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. PetersonUniversity 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 ofUCSD. Also in the wheel was a cosmic gamma-ray (>50MeV) sky survey instrument contributed byMIT, with PI Prof. William L. Kraushaar.
OSO-3 obtained extensive hard X-ray observations of solar flares, the cosmicdiffuse X-ray background, and multiple observations ofScorpius 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]
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]Archived March 2, 2021, at theWayback Machine (Public Domain)
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