REX

REX is an active satellite operated by United States, launched on 1991-06-29 from Vandenberg SFB, California. With over 35 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Low Earth Orbit (LEO) at altitudes between 765 km and 862 km with an inclination of 89.5°. It travels at approximately 26,815 km/h (7.45 km/s), completing one full orbit every 101 minutes — that’s roughly 14.24 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~100–500 years. Orbital Radar tracks REX in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

REX orbits at an average altitude of 814 km in the upper LEO band, where atmospheric drag is negligible and objects can persist for centuries to millennia. This altitude is used by broadband constellations like OneWeb and by scientific missions requiring stable orbits far from the densest debris bands. Within ±50 km of REX’s average altitude, there are currently 425 active payloads and 2,313 tracked debris or rocket body fragments — notable neighbours include NOAA 20, ONEWEB-0179, ONEWEB-0455. With an inclination of 89.5°, REX passes over latitudes between 89.5°N and 89.5°S, providing near-global coverage including the polar regions. Polar and near-polar orbits are used for reconnaissance, weather monitoring and Earth-observation missions that need to image every part of the planet. United States operates approximately 12,339 active satellites in total, of which 144 share a similar altitude band with REX.