USA 31

USA 31 is an active satellite operated by United States, launched on 1988-09-02 from Cape Canaveral, Florida. With over 38 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Medium Earth Orbit (MEO) at altitudes between 777 km and 39,553 km with an inclination of 27.7°. It travels at approximately 13,953 km/h (3.88 km/s), completing one full orbit every 11 hours 57 minutes — that’s roughly 2.01 orbits per day. Its orbital eccentricity of 0.7306 gives it a noticeably elliptical path, with significant altitude variation between perigee and apogee. Orbital Radar tracks USA 31 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

USA 31 orbits at an average altitude of 20,165 km in Medium Earth Orbit, the region between LEO and GEO (2,000–35,786 km). MEO’s higher altitude gives each satellite a much larger ground footprint than LEO, meaning fewer spacecraft are needed for global coverage — but signal latency is higher and radiation from the Van Allen belts is a significant design constraint. Within ±50 km of USA 31’s average altitude, there are currently 103 active payloads and 13 tracked debris or rocket body fragments — notable neighbours include GPS BIIR-5 (PRN 22), GPS BIIR-8 (PRN 16), GPS BIIR-11 (PRN 19). With an inclination of 27.7°, USA 31 passes over latitudes between 27.7°N and 27.7°S, covering the tropical and temperate zones where most of the world’s population resides. Low-to-mid inclination orbits are efficient to reach from equatorial and mid-latitude launch sites. United States operates approximately 12,360 active satellites in total, of which 43 share a similar altitude band with USA 31.