page_title: List of uncrewed NASA missions
section_title: High Energy Astronomy Observatory 1 (1977)
hierarchical_section_title: List of uncrewed NASA missions / List of missions / High Energy Astronomy Observatory 1 (1977)
caption_attribution_description: English: This image shows the HEAO-1 Satellite, a NASA High Energy Astronomy Observatory.
context_page_description: Since 1958, NASA has overseen more than 1,000 uncrewed missions into Earth orbit or beyond. It has both launched its own missions and provided funding for private-sector missions. A number of NASA missions, including the Explorers Program, Voyager program, and New Frontiers program, are ongoing.
context_section_description: The first of NASA's three High Energy Astronomy Observatories, HEAO 1, launched August 12, 1977, aboard an Atlas rocket with a Centaur upper stage, operated until January 9, 1979. During that time, it scanned the X-ray sky almost three times over 0.2 keV – 10 MeV, provided nearly constant monitoring of X-ray sources near the ecliptic poles, as well as more detailed studies of a number of objects through pointed observations.
  HEAO included four large X-ray and gamma-ray astronomy instruments, known as A1, A2, A3, and A4, respectively (before launch, HEAO 1 was known as HEAO A).  The orbital inclination was about 22.7 degrees. HEAO 1 re-entered the Earth's atmosphere on March 15, 1979.
caption: HEAO 1 Satellite