SL-3 R/B

SL-3 R/B is a spent rocket body associated with Russia (CIS), launched on 1981-10-13 from PKMTR on the Tselina-D launch. With over 45 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Low Earth Orbit (LEO) at altitudes between 491 km and 507 km with an inclination of 81.2°. It travels at approximately 27,422 km/h (7.62 km/s), completing one full orbit every 95 minutes — that’s roughly 15.22 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~1–3 years. Spent rocket bodies like SL-3 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-3 R/B orbits at an average altitude of 499 km in the core of Low Earth Orbit, the most heavily utilised altitude band. The balance of moderate drag (limiting debris accumulation) and short signal path (enabling low-latency links and high-resolution imaging) makes this regime the default for most commercial and government missions. Within ±50 km of SL-3 R/B’s average altitude, there are currently 9,238 active payloads and 238 tracked debris or rocket body fragments — notable neighbours include STARLINK-1017, STARLINK-1039, STARLINK-1047. This makes it one of the more crowded altitude bands, containing roughly 52.8% of all active satellites. With an inclination of 81.2°, SL-3 R/B passes over latitudes between 81.2°N and 81.2°S, providing near-global coverage including the polar regions. Polar and near-polar orbits are used for reconnaissance, weather monitoring and Earth-observation missions that need to image every part of the planet. Russia (CIS) operates approximately 1,287 active satellites in total, of which 59 share a similar altitude band with SL-3 R/B.