COSMOS 539

COSMOS 539 is an active satellite operated by OKB-10 (Russia (CIS)), launched on 1972-12-21 from Plesetsk Cosmodrome, Russia on the Sfera launch. After more than 54 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 1,341 km and 1,379 km with an inclination of 74.0°. It travels at approximately 25,850 km/h (7.18 km/s), completing one full orbit every 113 minutes — that’s roughly 12.75 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is thousands of years. Orbital Radar tracks COSMOS 539 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

COSMOS 539 orbits at an average altitude of 1,360 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 539’s average altitude, there are currently 122 active payloads and 247 tracked debris or rocket body fragments. With an inclination of 74.0°, COSMOS 539 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 98 share a similar altitude band with COSMOS 539.