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Gamma-ray Astronomy Satellites & Missions

Gamma-ray Astronomy Satellites & Missions

We present the many satellites which have detected electromagnetic radiation with energy greater than 100 keV by the decade in which the satellite was launched. You will see, as you go through the 1960s, 70s, 80s, and 90s, that the sensitivity increase in the detectors has developed greatly during the over 30 years of gamma-ray astronomy. In addition, our ability to localize the incident gamma-rays has developed enormously -- allowing us to obtain high-quality images of many fascinating celestial objects.

NOTE: We include here only missions which detected non-solar gamma-rays (intentionally or not).

The OSO-3 satellite under construction

The OSO-3 satellite under construction (Credit: Ball Aerospace)


The first dedicated gamma-ray astronomy mission was, in fact, the first high-energy astrophysics satellite as well. Explorer-XI was launched in 1961. The instrument package weighed 30 pounds, was 20 inches high and 10 inches in diameter. The experimenters believed that they detected 22 cosmic gamma rays. Their next detector, on Orbiting Solar Observatory -3, may be more accurately described as having proof of the discovery of cosmic gamma radiation, since it found a galactic plane anisotropy of high-energy gammas, much later to be confirmed with SAS-2 and COS-B. However, a totally unexpected but very important contributor to the origins of gamma ray astronomy in the 1960s and 1970s were the Vela satellites. Intended to watch for countries violating an international treaty banning atmospheric testing of nuclear weapons, they instead gave us the first hints at the odd phenomena of gamma-ray bursts.

All Gamma-ray missions active during the 1960s

OSO Series March 1962 - October 1978
Vela 5A/B and 6A/B May 1969 - June 1979
OGO Series September 1964 - March 1972
Cosmos Series March 1962 - Present
ORS Series September 1964 - March 1972
Luna Series January 1959 - August 1976
Proton Series July 1965 - July 1969
Ranger Program August 1961 - March 1965
Explorer 11 April 1961 - November 1961


The COS-B satellite (Credit: ESA)


The SAS-2 satellite in 1972 discovered a diffuse gamma-ray background, and the COS-B (1975 - 1982) satellite produced the first detailed map of the sky at gamma-ray wavelengths. A number of pulsars were discovered to also emit pulses at these wavelengths. The gamma-ray sky was found to be dominated by diffuse emission from the galactic plane, which at the highest energies (E > 100 MeV) is the decay of neutral pions generated in the collision of cosmic rays with interstellar gas.

All Gamma-ray missions active during the 1970s

HEAO August 1977 - May 1981
Cosmos Series March 1962 - Present
Prognoz Series April 1972 - January 1994
Venera Program February 1961 - July 1984
ISEE-3 August 1978 - May 1997
Pioneer Venus May 1978 - October 1992
SIGNE 3 June 1977 - June 1979
Solrad Series June 1960 - July 1977
Helios 2 January 1976 - December 1979
COS-B October 1975 - April 1982
OSO Series March 1962 - October 1978
Aryabhata April 1975
Mars Program October 1960 - March 1974
SAS Series December 1970 - April 1979
IMP Series November 1963 - October 2008
Radsat October 1972 - April 1974
Apollo 15 and 16 August 1971 - January 1973
TD-1A March 1972 - May 1974
Vela 5A/B and 6A/B May 1969 - June 1979


An artist's conception of the DMSP Block 5-2 satellites, which includes DSMP-8, DSMP-9, DSMP-10, DSMP-11, DSMP-12, DSMP-13, and DSMP-14. (Credit: USAF)


The decade of the 1980s saw a few missions occur which continued to gather data on gamma-ray burst distributions in the sky, gamma-ray emission from known X-ray sources, and so on. Much of this decade, however, went into the development of new technologies, technologies that would be needed to take gamma-ray astronomy to the next level of sensitivity and understanding.

All Gamma-ray missions active during the 1980s

Granat December 1989 - November 1998
Phobos July 1988 - March 1989
DMSP August 1962 - Present
Kvant-1 April 1987 - March 2001
Ginga February 1987 - November 1991
Prognoz Series April 1972 - January 1994
Venera Program February 1961 - July 1984
Solar Max February 1980 - December 1989

Impression of CGRO

An artist's conception of CGRO in oribt. (Credit: NASA)


With the launch of the Compton Gamma-Ray Observatory (CGRO) in April 1991, the field of gamma-ray astronomy at long last had its flagship. The satellite carried four major experiments which greatly improved the spatial and temporal resolution of gamma-ray observations. The CGRO ceased operation in June 2000, and was de-orbited by NASA. However, scientists are still studying its data to improve our understanding of the high-energy processes in our Universe.

All Gamma-ray missions active during the 1990s

DMSP August 1962 - Present
NEAR February 1996 - February 2001
RXTE December 1995 - January 2012
Wind November 1994 - Present
Mars Observer September 1992 - August 1993
EURECA July 1992 - July 1993
SROSS March 1987 - July 2001
CGRO April 1991 - June 2000
Ulysses October 1990 - June 2009
Gamma July 1990 - February 1992


An artist's impression of the INTEGRAL spacecraft in space. (Credit: ESA/Medialab)


The initial years of the 21st century see the a new fleet of gamma-ray instruments and observatories. With the result from Beppo-SAX and other observatories that gamma-ray bursts are at extra-galactic distances, Swift was poised to determine the nature of GRBs by performing rapid follow-up observations in X-ray and UV wavelengths. Fermi, launched in 2008, promises to be the premier gamma-ray observatory into the next decade.

All Gamma-ray missions active during the 2000s

HETE-2 October 2000 - March 2007
INTEGRAL October 2002 - Present
Swift November 2004 - present
Fermi (GLAST) June 2008 -


A service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA/GSFC

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