EXPLORER 20

EXPLORER 20 is an active satellite operated by GSFC (United States), launched on 1964-08-25 from Vandenberg Space Force Base, United States on the NASA S-48 launch. After more than 62 years in orbit, it is one of the longest-surviving objects in the space catalogue. It orbits in Low Earth Orbit (LEO) at altitudes between 852 km and 993 km with an inclination of 79.9°. It travels at approximately 26,614 km/h (7.39 km/s), completing one full orbit every 103 minutes — that’s roughly 13.92 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~100–500 years. Orbital Radar tracks EXPLORER 20 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

EXPLORER 20 orbits at an average altitude of 923 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 EXPLORER 20’s average altitude, there are currently 342 active payloads and 1,407 tracked debris or rocket body fragments. With an inclination of 79.9°, EXPLORER 20 passes over latitudes between 79.9°N and 79.9°S, covering most populated land masses in both hemispheres. This mid-inclination band balances global coverage with efficient launch energy requirements. United States operates approximately 13,276 active satellites in total, of which 165 share a similar altitude band with EXPLORER 20.