COSMOS 1851

COSMOS 1851 is an active satellite operated by PVO (Russia (CIS)), launched on 1987-06-12 from Plesetsk Cosmodrome, Russia on the Oko launch. With over 39 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Medium Earth Orbit (MEO) at altitudes between 7,632 km and 32,731 km with an inclination of 71.0°. It travels at approximately 13,948 km/h (3.87 km/s), completing one full orbit every 11 hours 58 minutes — that’s roughly 2.01 orbits per day. Its orbital eccentricity of 0.4726 gives it a noticeably elliptical path, with significant altitude variation between perigee and apogee. Orbital Radar tracks COSMOS 1851 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

COSMOS 1851 orbits at an average altitude of 20,182 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 1851’s average altitude, there are currently 104 active payloads and 13 tracked debris or rocket body fragments. With an inclination of 71.0°, COSMOS 1851 passes over latitudes between 71.0°N and 71.0°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 1,547 active satellites in total, of which 55 share a similar altitude band with COSMOS 1851.