2.2.2 spase://SMWG/Observatory/HEO3 HEO-3 2019-04-19T12:34:56.789Z The HEO acronym indicates satellites in a Highly Elliptical Orbit, also known as Molniya orbits. These orbits have period of roughly 12 hours, with a perigee of no more than a few hundred kilometers, apogee of roughly 7 Re, and an inclination of about 63 degrees. The three HEO spacecraft are referred to as HEO-1, HEO-2, and HEO-3 or F1, F2, and F3, meaning flights 1-3. Because science is not the primary mission of the host vehicle, many of the details on the HEO spacecraft cannot be released at this time. spase://SMWG/Person/T.Paul.OBrien GeneralContact spase://SMWG/Person/Joseph.F.Fennell GeneralContact ViRBO web page about HEO http://virbo.org/HEO Information about HEO data Earth.NearSurface