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 1,112 km and 2,658 km with an inclination of 65.8°. It travels at approximately 25,014 km/h (6.95 km/s), completing one full orbit every 2 hours 5 minutes — that’s roughly 11.56 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 1,885 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 5 active payloads and 19 tracked debris or rocket body fragments. This is a relatively sparse altitude band, containing less than 1% of all active satellites. 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.