SL-4 DEB

SL-4 DEB is a tracked piece of space debris attributed to Russia (CIS), launched on 2026-04-16 from PKMTR on the Unknown launch. As a relatively recent addition to the catalogue, its orbital elements are well-characterised. It orbits in Low Earth Orbit (LEO) at altitudes between 391 km and 457 km with an inclination of 98.2°. It travels at approximately 27,573 km/h (7.66 km/s), completing one full orbit every 93 minutes — that’s roughly 15.48 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. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~1–3 years. As orbital debris, SL-4 DEB poses a potential collision risk to operational satellites in nearby orbits and is continuously monitored by the U.S. Space Surveillance Network and other tracking systems.

SL-4 DEB orbits at an average altitude of 424 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-4 DEB’s average altitude, there are currently 3,355 active payloads and 136 tracked debris or rocket body fragments — notable neighbours include STARLINK-1008, STARLINK-1012, STARLINK-1017. This makes it one of the more crowded altitude bands, containing roughly 19.2% of all active satellites. With an inclination of 98.2°, SL-4 DEB passes over latitudes between 98.2°N and 98.2°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 1,285 active satellites in total, of which 42 share a similar altitude band with SL-4 DEB.