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Explorer 11 S-15 first space gamma-ray astronomy spacecraft family

Explorer 11 was a NASA Earth-orbiting gamma-ray observatory launched April 27, 1961. Its detector, sensitive above 50 MeV, was the first space-borne gamma-ray telescope and recorded cosmic gamma-ray events that initiated space-based gamma-ray astronomy; useful observations continued into September 1961.

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Identity

Aliases
Explorer 11Explorer XIS-15Explorer 11 spacecraftGamma-ray Explorer 11
Family Name
Explorer 11
Full Name
Explorer 11 S-15 first space gamma-ray astronomy spacecraft family
Roles
orbiterobservatoryresearch
Status
retired
Type
spacecraft

Details

Description
Explorer 11 was a NASA Earth-orbiting gamma-ray observatory launched April 27, 1961. Its detector, sensitive above 50 MeV, was the first space-borne gamma-ray telescope and recorded cosmic gamma-ray events that initiated space-based gamma-ray astronomy; useful observations continued into September 1961.
First Flight Year
1,961
Last Flight Year
1,961

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Creation Time
August 13, 2026 at 12:57:11 UTC
Updated Time
August 13, 2026 at 12:57:11 UTC