SL-6 R/B(2)

SL-6 R/B(2) is a spent rocket body associated with Russia (CIS), launched on 1977-09-22 from Baikonur, Kazakhstan. With over 49 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Medium Earth Orbit (MEO) at altitudes between 27,775 km and 167,910 km with an inclination of 51.3°. It travels at approximately 7,041 km/h (1.96 km/s), completing one full orbit every 93.0 hours — that’s roughly 0.26 orbits per day. Its orbital eccentricity of 0.6723 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-6 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-6 R/B(2) orbits at an average altitude of 97,843 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. With an inclination of 51.3°, SL-6 R/B(2) passes over latitudes between 51.3°N and 51.3°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 1,287 active satellites in total.