I'm looking for a primary reference of the altitude classifications of geocentric orbits (LEO, MEO, GEO, HEO), but I was not able to find something so far.

I noticed that there is very different information about this classification scheme, for example LEO: The English Wikipedia defines LEO from 160 to 2.000 km above mean sea level; in comparison, the German Wikipedia defines LEO from 200 to 1.200 km.

Does anybody know if there is an established standard for this orbit classification, e.g. at NASA, ESA or any other space agency, which can be referenced (f.i. a paper, guideline or handbook)?

Thank you really much!


NASA's GCMD (Global Change Master Directory) has a classification of orbits which contains the following defintions (truncated for the altitude portion):

  • LEO : Platforms that orbit between 80 km and 2000 km
  • MEO : Platform orbits lie between 2000 km to 35,786 km, but most commonly at 20,200 km or 20,650, with an orbital period of 12 hours).
  • GEO : Platform orbits with a revolution of exactly one day at an altitude of 35,786 km
  • HEO (High Earth Orbit): any orbit above geosynchronous (above 35,786 km)
  • HEO (Highly Elliptical Orbit) : an orbit of low perigee (about 1000 km) and a high apogee over 35,786 km).

They also define LPO (Lagrangian Point Orbits), but they don't define any heliocentric orbits. NASA's Earth Observatory uses the same LEO/MEO/GEO, but seems to lump LPO and Heliocentric into HEO.

And for referencing, see Citing GCMD Keywords

  • $\begingroup$ I haven't seen this website before. As it is written as Ancillary Description Writer's Guide by intention from an authoritative agency, it is quotable. This will help me; thank you very much! $\endgroup$ – saint Apr 20 '12 at 7:42

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