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The Uhuru Satellite

artist concept of Uhuru
Credit: NASA

Uhuru, also known as the Small Astronomical Satellite 1 (SAS-1) was the first earth-orbiting mission dedicated entirely to celestial X-ray astronomy. It was launched on 12 December 1970 from the San Marco platform in Kenya. December 12 was the seventh anniversary of the Kenyan independence and in recognition of the hospitality of the Kenyan people, the operating satellite was named Uhuru, which is the Swahili word for freedom. The mission operated over two years and ended in March 1973.

Mission Characteristics

* Lifetime: 12 Dec 1970 - March 1973
* Energy Range: 2-20 keV
* Payload: Two sets of proportional counters, 2-20 keV 0.084 m2
* Science Highlights:
  • First comprehensive and uniform all sky survey with a sensitivity of 10-3 the Crab intensity.
  • The 339 X-ray sources detected are binaries, supernova remnants, Seyfert galaxies and cluster of galaxies
  • Discovery of the diffuse X-ray emission from clusters of galaxies
* Archive: 4th Uhuru Catalog

Image of Uhuru satellite courtesy of SAO.

[About Uhuru] ( [Archive] ( [Gallery] ( [Publications] (

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