# Medium Earth orbit

Comparison of GPS, GLONASS, Galileo and Compass (medium earth orbit) satellite navigation system orbits with the International Space Station, Hubble Space Telescope and Iridium constellation orbits, Geostationary Earth Orbit, and the nominal size of the Earth.[a] The Moon's orbit is around 9 times larger (in radius and length) than geostationary orbit.[b]
To-scale diagram of low, medium and high earth orbits

Medium Earth orbit (MEO), sometimes called intermediate circular orbit (ICO), is the region of space around the Earth above low Earth orbit (altitude of 2,000 kilometres (1,243 mi)) and below geostationary orbit (altitude of 35,786 kilometres (22,236 mi)).[1]

The most common use for satellites in this region is for navigation, communication, and geodetic/space environment science.[1] The most common altitude is approximately 20,200 kilometres (12,552 mi)), which yields an orbital period of 12 hours, as used, for example, by the Global Positioning System (GPS).[1] Other satellites in Medium Earth Orbit include Glonass (with an altitude of 19,100 kilometres (11,868 mi)) and Galileo (with an altitude of 23,222 kilometres (14,429 mi)) constellations.[citation needed] Communications satellites that cover the North and South Pole are also put in MEO.[2]

The orbital periods of MEO satellites range from about 2 to nearly 24 hours.[1] Telstar 1, an experimental satellite launched in 1962, orbits in MEO.[3]

The orbit is home to a number of satellites.[1]

## Notes

1. ^ Orbital periods and speeds are calculated using the relations 4π²R³ = T²GM and V²R = GM, where R = radius of orbit in metres, T = orbital period in seconds, V = orbital speed in m/s, G = gravitational constant ≈ 6.673×10−11 Nm²/kg², M = mass of Earth ≈ 5.98×1024 kg.
2. ^ Approximately 8.6 times when the moon is nearest (363 104 km ÷ 42 164 km) to 9.6 times when the moon is farthest (405 696 km ÷ 42 164 km).

## References

1. "Definitions of geocentric orbits from the Goddard Space Flight Center". User support guide: platforms. NASA Goddard Space Flight Center. Retrieved 2012-07-08.
2. ^ Satellite Basics: Solution Benefits
3. ^ Medium Earth Orbit