USA 143

USA 143 is an active satellite operated by United States, launched on 1999-04-30 from Cape Canaveral, Florida. With over 27 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Medium Earth Orbit (MEO) at altitudes between 1,097 km and 5,148 km with an inclination of 28.2°. It travels at approximately 23,327 km/h (6.48 km/s), completing one full orbit every 2 hours 34 minutes — that’s roughly 9.38 orbits per day. Its orbital eccentricity of 0.2134 gives it a noticeably elliptical path, with significant altitude variation between perigee and apogee. Orbital Radar tracks USA 143 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

USA 143 orbits at an average altitude of 3,123 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 143’s average altitude, there are currently 1 active payload and 3 tracked debris or rocket body fragments. This is a relatively sparse altitude band, containing less than 1% of all active satellites. With an inclination of 28.2°, USA 143 passes over latitudes between 28.2°N and 28.2°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 12,339 active satellites in total.