COSMOS 621

COSMOS 621 is an active satellite operated by GUKOS RVSN (Russia (CIS)), launched on 1973-12-19 from Plesetsk Cosmodrome, Russia on the Strela-1M 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 1,406 km and 1,484 km with an inclination of 74.0°. It travels at approximately 25,709 km/h (7.14 km/s), completing one full orbit every 115 minutes — that’s roughly 12.55 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is thousands of years. Orbital Radar tracks COSMOS 621 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

COSMOS 621 orbits at an average altitude of 1,445 km in the uppermost reaches of Low Earth Orbit. At this altitude, orbital decay is effectively zero without active deorbiting, and coverage footprints are significantly larger than lower LEO, though at the cost of higher latency. Within ±50 km of COSMOS 621’s average altitude, there are currently 572 active payloads and 335 tracked debris or rocket body fragments. With an inclination of 74.0°, COSMOS 621 passes over latitudes between 74.0°N and 74.0°S, covering most populated land masses in both hemispheres. This mid-inclination band balances global coverage with efficient launch energy requirements. Russia (CIS) operates approximately 1,553 active satellites in total, of which 515 share a similar altitude band with COSMOS 621.