Orbit class
Highly Elliptical Orbit (HEO)
Eccentric orbits where the satellite swings close to Earth at perigee and far out at apogee. Includes Molniya, Tundra, GTO, and deep-elliptical science missions.
30 cataloged objects in this orbit class.
HEO is the umbrella for eccentric orbits with apogee well above the geosynchronous belt. The classics: Molniya (12-hour period, 63.4° inclination, perigee ~600 km, apogee ~40,000 km — used by Russia for high-latitude comms), Tundra (24-hour version, used by SiriusXM), GTO (Geostationary Transfer Orbit — where every newly launched GEO comm satellite spends days/weeks before circularizing), and deep-elliptical science missions like ESA's Cluster II with apogee ~119,000 km.