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 108 h 39 min 37.8°
IBEX 2008-051A 2008-10-19 61,941 km 290,906 km 216 h 3 min 16.9°
TESS[5][6] 2018-038A 2018-04-18 108,000 km 375,000 km 328 h 48 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". Astronautix.com. Retrieved November 12, 2022.
  4. "Trajectory Details for Vela 1A from the National Space Science Data Center". Retrieved November 12, 2022.
  5. "MIT TESS mission". Retrieved November 12, 2022.
  6. "NASA - TESS Science Support Center".
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