Tags: Artificialsatellite, Satellite.
The last of NASA’s three High Energy Astronomy Observatories HEAO 3 was launched 20 September 1979 on an Atlas-Centaur launch vehicle into a nearly circular 43.6 degree inclination low-Earth orbit with an initial perigee of 486.4 km.The normal operating mode was a continuous celestial scan spinning approximately once every 20 min about the spacecraft z-axis which was nominally pointed at the Sun.Total mass of the observatory at launch was 2660.0 kilograms (5864.3 lb).HEAO 3 included three scientific instruments: the first a cryogenic high-resolution germanium gamma-ray spectrometer and two devoted to cosmic-ray observations.The scientific objectives of the mission’s three experiments were:(1) to study intensity spectrum and time behavior of X-ray and gamma-ray sources between 0.06 and 10 MeV; measure isotropy of the diffuse X-ray and gamma-ray background; and perform an exploratory search for X-and gamma-ray line emissions;(2) to determine the isotopic composition of the most abundant components of the cosmic-ray flux with atomic mass between 7 and 56 and the flux of each element with atomic number (Z) between Z = 4 and Z = 50;(3) to search for super-heavy nuclei up to Z = 120 and measure the composition of the nuclei with Z >20.↑
