High Earth orbit

A high Earth orbit is a geocentric orbit with an altitude entirely above that of a geosynchronous orbit (35,786 kilometres, 22,236 mi).[1] The orbital periods of such orbits are greater than 24 hours, therefore satellites in such orbits have an apparent retrograde motion – that is, even if they are in a prograde orbit (0° ≤ inclination < 90°), their orbital velocity is lower than Earth's rotational speed, causing their ground track to move westward on Earth's surface.[2]

This article is about a variation of geocentric orbit. For elliptic orbit, see Highly elliptical orbit.
To-scale diagram of low, medium and high Earth orbits

Examples of satellites in high Earth orbit
Name NSSDC id. Launch date Perigee Apogee Period Inclination
Vela 1A[3][4] 1963-039A 1963-10-17 101,925 km 116,528 km 6,519 min 37.8°
IBEX 2008-051A 2008-10-19 61,941 km 290,906 km 12,963 min 16.9°
TESS[5][6] 2018-038A 2018-04-18 108,000 km 375,000 km 19,728 min 37.00°

See also

References
  1. "Definitions of geocentric orbits from the Goddard Space Flight Center". User support guide: platforms. NASA Goddard Space Flight Center. Archived from the original on 2010-05-27. Retrieved 2012-07-08.
  2. "Types of orbits". www.esa.int. Retrieved 2021-08-20.
  3. Vela at Encyclopedia Astronautica
  4. Trajectory Details for Vela 1A from the National Space Science Data Center
  5. https://tess.mit.edu/
  6. "NASA - TESS Science Support Center".
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