NNSS 20 (TRANSIT 20)

NNSS 20 (TRANSIT 20) is an active satellite operated by USN NAVAIR (United States), launched on 1973-10-30 from Vandenberg Space Force Base, United States on the NNS O-20 launch. After more than 53 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 882 km and 1,107 km with an inclination of 89.9°. It travels at approximately 26,483 km/h (7.36 km/s), completing one full orbit every 105 minutes — that’s roughly 13.72 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~100–500 years. Orbital Radar tracks NNSS 20 (TRANSIT 20) in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

NNSS 20 (TRANSIT 20) orbits at an average altitude of 995 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 NNSS 20 (TRANSIT 20)’s average altitude, there are currently 339 active payloads and 1,090 tracked debris or rocket body fragments. With an inclination of 89.9°, NNSS 20 (TRANSIT 20) passes over latitudes between 89.9°N and 89.9°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 13,279 active satellites in total, of which 100 share a similar altitude band with NNSS 20 (TRANSIT 20).