COSMOS 839 DEB

COSMOS 839 DEB is a tracked piece of space debris attributed to Russia (CIS), launched on 1976-07-08 from PKMTR. 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 887 km and 2,079 km with an inclination of 66.0°. It travels at approximately 25,646 km/h (7.12 km/s), completing one full orbit every 116 minutes — that’s roughly 12.46 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is thousands of years. As orbital debris, COSMOS 839 DEB poses a potential collision risk to operational satellites in nearby orbits and is continuously monitored by the U.S. Space Surveillance Network and other tracking systems.

COSMOS 839 DEB orbits at an average altitude of 1,483 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 DEB’s average altitude, there are currently 295 active payloads and 239 tracked debris or rocket body fragments. With an inclination of 66.0°, COSMOS 839 DEB passes over latitudes between 66.0°N and 66.0°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 1,287 active satellites in total, of which 287 share a similar altitude band with COSMOS 839 DEB.