SL-6 R/B(2)

SL-6 R/B(2) is a spent rocket body associated with Russia (CIS), launched on 1985-05-29 from PKMTR on the Molniya-3 No. 39 launch. With over 41 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Highly Elliptical Orbit (HEO) at altitudes between 522 km and 40,490 km with an inclination of 62.1°. It travels at approximately 13,864 km/h (3.85 km/s), completing one full orbit every 12 hours 11 minutes — that’s roughly 1.97 orbits per day. Its orbital eccentricity of 0.7435 gives it a noticeably elliptical path, with significant altitude variation between perigee and apogee. 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) follows a Highly Elliptical Orbit, sweeping between 522 km (perigee) and 40,490 km (apogee). It spends most of its 12 hours 11 minutes orbital period near apogee, effectively loitering over a region of interest before rapidly sweeping through perigee — a profile used for high-latitude communications (Molniya orbits), early-warning systems and magnetospheric science. Within ±50 km of SL-6 R/B(2)’s average altitude, there are currently 0 active payloads and 16 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 62.1°, SL-6 R/B(2) passes over latitudes between 62.1°N and 62.1°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.