1.Previous
3.Next

at an altitude of approximately 20200 km has an orbital period of 12 hours and passes over the same two spots on the equator every day. This reliably predictable orbit is used by the Global Positioning System (GPS) constellation. Other navigation satellite systems use similar medium Earth orbits including GLONASS (with an altitude of 19100 km), Galileo (with

1.Previous
3.Next