SL-12 R/B(2)

SL-12 R/B(2) is a spent rocket body associated with Russia (CIS), launched on 1978-12-19 from Baikonur, Kazakhstan on the Gorizont No. 11L launch. With over 48 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Medium Earth Orbit (MEO) at altitudes between 22,912 km and 47,924 km with an inclination of 12.6°. It travels at approximately 11,118 km/h (3.09 km/s), completing one full orbit every 23 hours 37 minutes — that’s roughly 1.02 orbits per day. Its orbital eccentricity of 0.2993 gives it a noticeably elliptical path, with significant altitude variation between perigee and apogee. At geostationary altitude, there is no meaningful atmospheric drag — this object will remain in orbit indefinitely unless actively deorbited. Spent rocket bodies like SL-12 R/B(2) are among the largest pieces of uncontrolled space debris and are priority targets for collision avoidance manoeuvres and future active debris removal efforts.

SL-12 R/B(2) orbits at an average altitude of 35,418 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-12 R/B(2)’s average altitude, there are currently 1 active payload and 14 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 12.6°, SL-12 R/B(2) passes over latitudes between 12.6°N and 12.6°S, concentrating coverage over equatorial and near-equatorial regions. Low-inclination orbits maximise revisit rates over specific tropical zones. Russia (CIS) operates approximately 1,287 active satellites in total.