SL-4 R/B

SL-4 R/B is a spent rocket body associated with Russia (CIS), launched on 2014-04-16 from Baikonur Cosmodrome, Kazakhstan on the Egyptsat-2 launch. After 12 years in orbit, it continues to be tracked by global surveillance networks. It orbits in Low Earth Orbit (LEO) at altitudes between 375 km and 490 km with an inclination of 51.6°. It travels at approximately 27,555 km/h (7.65 km/s), completing one full orbit every 93 minutes — that’s roughly 15.45 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~1–3 years. Spent rocket bodies like SL-4 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-4 R/B orbits at an average altitude of 433 km in the core of Low Earth Orbit, the most heavily utilised altitude band. The balance of moderate drag (limiting debris accumulation) and short signal path (enabling low-latency links and high-resolution imaging) makes this regime the default for most commercial and government missions. Within ±50 km of SL-4 R/B’s average altitude, there are currently 9,892 active payloads and 122 tracked debris or rocket body fragments — notable neighbours include ISS (ZARYA), STARLINK-1017, STARLINK-1039. This makes it one of the more crowded altitude bands, containing roughly 52.9% of all active satellites. With an inclination of 51.6°, SL-4 R/B passes over latitudes between 51.6°N and 51.6°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 1,516 active satellites in total, of which 37 share a similar altitude band with SL-4 R/B.