SL-8 R/B

SL-8 R/B is a spent rocket body associated with Russia (CIS), launched on 1970-10-12 from Plesetsk Cosmodrome, Russia on the Tsiklon launch. After more than 56 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 674 km and 688 km with an inclination of 74.0°. It travels at approximately 27,065 km/h (7.52 km/s), completing one full orbit every 98 minutes — that’s roughly 14.64 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~10–25 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 681 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 SL-8 R/B’s average altitude, there are currently 344 active payloads and 1,348 tracked debris or rocket body fragments — notable neighbours include TERRA, AQUA, ONEWEB-0179. 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 19 share a similar altitude band with SL-8 R/B.