SL-18 R/B

SL-18 R/B is a spent rocket body associated with Russia (CIS), launched on 2001-02-20 from SVOB on the Odin launch. With over 25 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Low Earth Orbit (LEO) at altitudes between 537 km and 549 km with an inclination of 97.7°. It travels at approximately 27,334 km/h (7.59 km/s), completing one full orbit every 96 minutes — that’s roughly 15.08 orbits per day. Its near-polar, sun-synchronous orbit means it passes over any given point on Earth at approximately the same local solar time, ideal for consistent Earth observation lighting conditions. Its near-circular orbit (eccentricity close to zero) means it maintains a very consistent altitude throughout each revolution. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~3–10 years. Spent rocket bodies like SL-18 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-18 R/B orbits at an average altitude of 543 km in a sun-synchronous orbit (SSO), a specialised subset of LEO where the orbital plane precesses to maintain a constant angle relative to the Sun. This provides consistent lighting conditions on every pass — essential for Earth observation, weather monitoring and environmental science. Within ±50 km of SL-18 R/B’s average altitude, there are currently 3,453 active payloads and 343 tracked debris or rocket body fragments — notable neighbours include STARLINK-1184, STARLINK-1276, STARLINK-1451. This makes it one of the more crowded altitude bands, containing roughly 19.7% of all active satellites. With an inclination of 97.7°, SL-18 R/B passes over latitudes between 97.7°N and 97.7°S, providing near-global coverage including the polar regions. Polar and near-polar orbits are used for reconnaissance, weather monitoring and Earth-observation missions that need to image every part of the planet. Russia (CIS) operates approximately 1,286 active satellites in total, of which 45 share a similar altitude band with SL-18 R/B.