OSO 3

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American satellite launched in 1967

title: "OSO 3" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["spacecraft-launched-in-1967", "satellites-formerly-orbiting-earth"] description: "American satellite launched in 1967" topic_path: "general/spacecraft-launched-in-1967" source: "https://en.wikipedia.org/wiki/OSO_3" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary American satellite launched in 1967 ::

::data[format=table title="Infobox spaceflight"]

Field	Value
name	OSO 3
image	Oso3 small.gif
image_caption	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
manufacturer	BBRC
launch_mass	281 kg
launch_date	UTC
launch_rocket	Delta C
launch_site	Cape Canaveral LC-17A
last_contact
decay_date	April 4, 1982
orbit_epoch	May 8, 1967, 11:19:00 UTC
orbit_reference	Geocentric
orbit_regime	Low Earth
orbit_periapsis	534 km
orbit_apoapsis	564 km
orbit_inclination	32.87 degrees
orbit_eccentricity	0.002164
orbit_mean_motion	15.07
orbit_period	95.53 minutes
apsis	gee
::

| name = OSO 3 | image = Oso3 small.gif | image_caption = 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

| launch_date = UTC | launch_rocket = Delta C | launch_site = Cape Canaveral LC-17A | launch_contractor =

| last_contact = | decay_date = April 4, 1982

OSO 3 (Orbiting Solar Observatory 3), or Third Orbiting Solar Observatory (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

::data[format=table title="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.

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

References

"NASA - NSSDCA - Spacecraft - Trajectory Details".
[https://web.archive.org/web/19980224154422/http://imagine.gsfc.nasa.gov/docs/sats_n_data/xray_missions.html NASA GSFC X-ray Astronomy Satellites and Missions]
[http://heasarc.gsfc.nasa.gov/docs/heasarc/missions/oso3.html] {{Webarchive. link. (August 13, 2009 GSFC HEASARC "The Third Orbiting Solar Observatory (OSO-3)")
Peterson, Laurence E.. (1966-01-24). "Spectrum of Crab Nebula X Rays to 120 keV". American Physical Society (APS).
Peterson, Laurence E.. (1966). "The Spectrum of Scorpius XR-1 to 50 KEV". American Astronomical Society.
Hudson, Hugh S.. (1970). "Simultaneous X-Ray and Optical Observations of SCO X-1 Flares". American Astronomical Society.
Pelling, R. M. 1971, Ph.D. dissertation thesis, University of California at San Diego
Kraushaar, W. L.. (1972). "High-Energy Cosmic Gamma-Ray Observations from the OSO-3 Satellite". American Astronomical Society.

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