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 991 km and 2,085 km with an inclination of 65.8°. It travels at approximately 25,557 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. 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 1,538 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 124 active payloads and 266 tracked debris or rocket body fragments. With an inclination of 65.8°, COSMOS 839 DEB 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 1,286 active satellites in total, of which 112 share a similar altitude band with COSMOS 839 DEB.