SL-12 R/B(2)

SL-12 R/B(2) is a spent rocket body associated with Russia (CIS), launched on 1999-06-18 from Baikonur, Kazakhstan on the Astra 1H launch. With over 27 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Medium Earth Orbit (MEO) at altitudes between 7,370 km and 35,769 km with an inclination of 17.5°. It travels at approximately 13,597 km/h (3.78 km/s), completing one full orbit every 12 hours 55 minutes — that’s roughly 1.86 orbits per day. Its orbital eccentricity of 0.5082 gives it a noticeably elliptical path, with significant altitude variation between perigee and apogee. 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 21,570 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 39 active payloads and 9 tracked debris or rocket body fragments — notable neighbours include GALILEO 5 (261), GALILEO 6 (262). This is a relatively sparse altitude band, containing less than 1% of all active satellites. With an inclination of 17.5°, SL-12 R/B(2) passes over latitudes between 17.5°N and 17.5°S, concentrating coverage over equatorial and near-equatorial regions. Low-inclination orbits maximise revisit rates over specific tropical zones. Russia (CIS) operates approximately 1,286 active satellites in total.