mediumEarthorbit

Medium Earth orbit (MEO) is the region of space around Earth at altitudes between low Earth orbit (LEO) and geostationary orbit (GEO). By convention, MEO extends roughly from 2,000 kilometers (1,240 miles) to 35,786 kilometers (22,236 miles) above Earth's surface. Orbits in this range have orbital periods from about 2 hours to nearly 24 hours, depending on altitude and eccentricity.

Medium Earth orbit is used by several satellite navigation systems because it provides good coverage with relatively moderate signals. The major constellations—Global Positioning System (GPS), Galileo, GLONASS, and BeiDou—place their satellites in MEO. These satellites typically follow near-circular, inclined orbits to maximize global coverage and repeat ground tracks. Other missions, including some communications and scientific satellites, also operate in MEO.

Orbit maintenance in MEO requires accounting for gravitational perturbations from the Moon and Sun, Earth's oblateness, and solar radiation pressure. Compared with LEO, MEO experiences less atmospheric drag and longer potential lifetimes, but with higher radiation exposure than LEO; compared with GEO, MEO satellites have lower altitude, enabling smaller launch energy and shorter access to orbit, but require more satellites to achieve continuous global coverage.

Examples of MEO constellations include GPS at about 20,200 km altitude with ~55° inclination; Galileo at about 23,222 km with ~56° inclination; GLONASS at about 19,100 km with ~64.8° inclination; BeiDou-3 at about 21,500 km altitude with ~55° inclination.