SL-11 R/B

SL-11 R/B is a spent rocket body associated with Russia (CIS), launched on 1970-10-23 from Baikonur Cosmodrome, Kazakhstan on the I2P launch. After more than 56 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 513 km and 2,044 km with an inclination of 62.9°. It travels at approximately 25,987 km/h (7.22 km/s), completing one full orbit every 111 minutes — that’s roughly 12.96 orbits per day. Its orbital eccentricity of 0.1001 gives it a noticeably elliptical path, with significant altitude variation between perigee and apogee. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is thousands of years. Spent rocket bodies like SL-11 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-11 R/B orbits at an average altitude of 1,279 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-11 R/B’s average altitude, there are currently 20 active payloads and 381 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 62.9°, SL-11 R/B passes over latitudes between 62.9°N and 62.9°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 5 share a similar altitude band with SL-11 R/B.