SL-8 R/B

SL-8 R/B is a spent rocket body associated with Russia (CIS), launched on 1972-12-21 from Plesetsk Cosmodrome, Russia on the Sfera launch. After more than 54 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 1,334 km and 1,372 km with an inclination of 74.0°. It travels at approximately 25,861 km/h (7.18 km/s), completing one full orbit every 113 minutes — that’s roughly 12.77 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 1,353 km in the uppermost reaches of Low Earth Orbit. At this altitude, orbital decay is effectively zero without active deorbiting, and coverage footprints are significantly larger than lower LEO, though at the cost of higher latency. Within ±50 km of SL-8 R/B’s average altitude, there are currently 67 active payloads and 230 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 74.0°, SL-8 R/B 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 47 share a similar altitude band with SL-8 R/B.