NASA launches the third and final High Energy Astronomy Observatory satellite into Earth orbit, where it begins studying gamma ray sources and the nature of cosmic rays. There is also an experiment package designed to detect heavy atomic nuclei. HEAO-3 will remain in service through May 1981, and it will re-enter Earth’s atmosphere in December of that year.
theLogBook.com
https://www.theLogBook.com
Earl Green is the creator, curator, and head writer of theLogBook.com.
Also of interest...
Orbiting Astronomical Observatory 3: Copernicus
August 21, 1972
TIROS-1
April 1, 1960
Viking 2 and the frost of Mars
September 25, 1977