COSMOS 858

COSMOS 858 is an active satellite operated by Russia (CIS), launched on 1976-09-29 from Plesetsk Cosmodrome, Russia on the Strela-2M launch. After more than 50 years in orbit, it is one of the longest-surviving objects in the space catalogue. It orbits in Low Earth Orbit (LEO) at altitudes between 765 km and 784 km with an inclination of 74.0°. It travels at approximately 26,888 km/h (7.47 km/s), completing one full orbit every 100 minutes — that’s roughly 14.35 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~25–100 years. Orbital Radar tracks COSMOS 858 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

COSMOS 858 orbits at an average altitude of 775 km in the mid-LEO band, where atmospheric drag is minimal but radiation exposure remains manageable. Objects at this altitude persist for decades to centuries, making debris mitigation critical. This regime is popular for remote sensing constellations and scientific instruments that need stable, long-duration orbits. Within ±50 km of COSMOS 858’s average altitude, there are currently 444 active payloads and 2,331 tracked debris or rocket body fragments — notable neighbours include ONEWEB-0455. With an inclination of 74.0°, COSMOS 858 passes over latitudes between 74.0°N and 74.0°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 1,537 active satellites in total, of which 73 share a similar altitude band with COSMOS 858.