SL-8 R/B

SL-8 R/B is a spent rocket body associated with Russia (CIS), launched on 1976-07-08 from Plesetsk Cosmodrome, Russia on the Lira launch. 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 960 km and 2,092 km with an inclination of 65.9°. It travels at approximately 25,576 km/h (7.10 km/s), completing one full orbit every 117 minutes — that’s roughly 12.35 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is thousands of years. Spent rocket bodies like SL-8 R/B are among the largest pieces of uncontrolled space debris and are priority targets for collision avoidance manoeuvres and future active debris removal efforts.

SL-8 R/B orbits at an average altitude of 1,526 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 SL-8 R/B’s average altitude, there are currently 211 active payloads and 392 tracked debris or rocket body fragments. With an inclination of 65.9°, SL-8 R/B passes over latitudes between 65.9°N and 65.9°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 197 share a similar altitude band with SL-8 R/B.