`Height' h is defined as geocentric semi-major axis minus Earth equatorial radius: (a-6378.0 km); i.e.
average of conventional perigee (hp) and apogee (ha) heights. Heights are in km, inclination in degrees.
One common conventional upper boundary of LEO is a 2 hour period (and it's enshrined
in code as part of the SGP4 model.) Orbital period makes the most
sense for defining boundaries between there and GEO, while height makes the most sense
for the lower boundaries. This makes the definition scheme a bit patchwork - sorry.
Prior to release 1.3 (Sep 2022) I used a 2-hour period (1681 km altitude) as the
upper boundary of LEO. I now use 2000 km altitude, which has become the more common usage
in recent years.
| Code | Name | Period (hr:min) | Height (km) | Inclination (deg) | Eccentricity |
|---|---|---|---|---|---|
| ATM | Atmospheric | ha below 80 | |||
| SO | Suborbital | hp below 0, ha above 80 | |||
| TA | Trans-Atm. | hp from 0 to 80, ha above 80 | |||
| LLEO/E | Lower LEO/Equatorial | h 80 to 600 | 0 to 25 | ||
| LLEO/I | Lower LEO/Intermediate | h 80 to 600 | 25 to 85 | ||
| LLEO/P | Lower LEO/Polar | h 80 to 600 | 85 to 95 | ||
| LLEO/S | Lower LEO/Sun-Sync | h 80 to 600 | 95 to 104 | ||
| LLEO/R | Lower LEO/Retrograde | h 80 to 600 | 104 to 180 | ||
| LEO/E | Upper LEO/Equatorial | Up to 2:00 | h 600 to 1681 | 0 to 25 | |
| LEO/I | Upper LEO/Intermediate | Up to 2:00 | h 600 to 1681 | 25 to 85 | |
| LEO/P | Upper LEO/Polar | Up to 2:00 | h 600 to 1681 | 85 to 95 | |
| LEO/S | Upper LEO/Sun-Sync | Up to 2:00 | h 600 to 1681 | 95 to 104 | |
| LEO/R | Upper LEO/Retrograde | Up to 2:00 | h 600 to 1681 | 104 to 180 | |
| MEO | Medium Earth Orbit | 2:00 - 23:00 | 0.00-0.50 | ||
| HEO | Highly Elliptical orbit | 4:03 - 23:00 | 0.50-0.92 | ||
| HEO/M | Molniya | 11:30 - 12:30 | 62.0 - 64.0 | 0.50 - 0.77 | |
| GTO | Geotransfer | 10:00 - 12:30 | 0.0 - 85.0 | 0.50 - 0.77 | |
| GEO/S | Stationary | 23:55.5-23:56.5 | 0.0 - 3.0 | 0.00 - 0.01 | |
| GEO/I | Inclined GEO | 23:55.5-23:56.5 | 3.0 - 25.0 | 0.00 - 0.05 | |
| GEO/T | Synchronous | 23:55.5-23:56.5 | 0.0 - 180.0 | 0.00 - 0.85 | |
| GEO/D | Drift GEO | 23:00 - 25:00 | 0.0 - 3.0 | 0.00 - 0.05 | |
| GEO/SI | Inclined GEO | 23:55.5-23:56.5 | 3.0 - 25.0 | 0.00 - 0.05 | |
| GEO/ID | Inclined Drift | 23:41 - 24:11 | 3.0 - 25.0 | 0.00 - 0.05 | |
| GEO/NS | Near-sync | 23:00 - 25:00 | 0.0 - 180.0 | 0.0 - 0.85 | |
| VHEO | Very High Earth Orbit | Above 25:00 | 0.0 - 180.0 | 0.0 - 1.00 | |
| DSO | Deep Space Orbit | h above 145688 to 318200 | 0.0 to 1.0 | ||
| CLO | Cislunar/Translunar | h from 318200 to 1.5 million | 0.0 to 1.0 | ||
| EEO | Earth Escape | h less than 1.5 million | Above 1.0 | ||
| HCO | Heliocentric | h more than 1.5 million | Heliocentric e 0.0 to 1.0 | ||
| PCO | Planetocentric | Central body not Earth or Sun | |||
| SSE | Solar System Escape | Heliocentric e above 1.0 |