SL-8 R/B

SL-8 R/B is a spent rocket body associated with Russia (CIS), launched on 1977-05-19 from PKMTR on the Lira launch. With over 49 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Medium Earth Orbit (MEO) at altitudes between 989 km and 2,091 km with an inclination of 65.9°. It travels at approximately 25,554 km/h (7.10 km/s), completing one full orbit every 117 minutes — that’s roughly 12.32 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 1,540 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 120 active payloads and 262 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 1,286 active satellites in total, of which 107 share a similar altitude band with SL-8 R/B.