COSMOS 839

COSMOS 839 is an active satellite operated by Russia (CIS), launched on 1976-07-08 from Plesetsk Cosmodrome, Russia on the Lira launch. After more than 50 years in orbit, it is one of the longest-surviving objects in the space catalogue. It orbits in Medium Earth Orbit (MEO) at altitudes between 975 km and 2,099 km with an inclination of 65.8°. It travels at approximately 25,559 km/h (7.10 km/s), completing one full orbit every 117 minutes — that’s roughly 12.33 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is thousands of years. Orbital Radar tracks COSMOS 839 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

COSMOS 839 orbits at an average altitude of 1,537 km in Medium Earth Orbit, the region between LEO and GEO (2,000–35,786 km). MEO’s higher altitude gives each satellite a much larger ground footprint than LEO, meaning fewer spacecraft are needed for global coverage — but signal latency is higher and radiation from the Van Allen belts is a significant design constraint. Within ±50 km of COSMOS 839’s average altitude, there are currently 167 active payloads and 399 tracked debris or rocket body fragments. With an inclination of 65.8°, COSMOS 839 passes over latitudes between 65.8°N and 65.8°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 1,537 active satellites in total, of which 148 share a similar altitude band with COSMOS 839.