Global Positioning System (GPS) satellites cruise at roughly 14,000 km/h (about 3.9 km/s) relative to the rotating Earth. This velocity ensures that each satellite completes two orbits around Earth every sidereal day—approximately 11 hours 58 minutes—providing continuous global coverage.
Six orbital planes, each inclined 55° from the equator, host four satellites per plane. This arrangement delivers optimal sky coverage for receivers worldwide while avoiding the limitations of a single, equatorial geostationary orbit.
Geostationary satellites orbit at ~35,786 km altitude and remain fixed above one point on Earth’s equator, ideal for fixed‑point communications but unsuitable for GPS. Because GPS satellites must service all latitudes and do not rely on fixed ground antennas, a higher‑altitude, inclined, faster orbit allows the system to maintain global accuracy and redundancy.
GPS satellites are synchronized to the sidereal day—the time the stars take to return to the same position—rather than the solar day. This alignment keeps the satellite network’s geometry consistent relative to the stars, simplifying orbit maintenance and reducing the need for extra propulsion to counter Earth’s rotation.
Using Newton’s law of gravitation and centripetal acceleration:
These figures match observed GPS satellite telemetry and confirm the system’s precise orbital dynamics.
GPS satellites move at a steady ~14,000 km/h, completing two orbits each sidereal day. Their inclined, high‑altitude orbits—rather than geostationary paths—provide worldwide, reliable positioning for billions of users.
