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Definition: HEO

(1) (High Earth Orbit) A communications satellite orbit that is higher than a geostationary earth orbit (see GEO).

(2) (Highly Elliptical Orbit) A communications satellite that travels in a figure-8 elliptical pattern. It has its longest duration when it is farthest from the earth (at its apogee) and is in a high earth orbit at that point (definition #1 above). For example, Sirius Satellite Radio uses a constellation of three satellites in the highly elliptical Tundra orbits over North and South America. See GEO and LEO.