EPSILON R/B

EPSILON R/B is a spent rocket body associated with Japan, launched on 2013-09-14 from Uchinoura, Japan on the SPRINT-A launch. After 13 years in orbit, it continues to be tracked by global surveillance networks. It orbits in Low Earth Orbit (LEO) at altitudes between 806 km and 970 km with an inclination of 29.8°. It travels at approximately 26,677 km/h (7.41 km/s), completing one full orbit every 103 minutes — that’s roughly 14.02 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~100–500 years. Spent rocket bodies like EPSILON 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.

EPSILON R/B orbits at an average altitude of 888 km in the upper LEO band, where atmospheric drag is negligible and objects can persist for centuries to millennia. This altitude is used by broadband constellations like OneWeb and by scientific missions requiring stable orbits far from the densest debris bands. Within ±50 km of EPSILON R/B’s average altitude, there are currently 169 active payloads and 1,568 tracked debris or rocket body fragments. With an inclination of 29.8°, EPSILON R/B passes over latitudes between 29.8°N and 29.8°S, covering the tropical and temperate zones where most of the world’s population resides. Low-to-mid inclination orbits are efficient to reach from equatorial and mid-latitude launch sites. Japan operates approximately 190 active satellites in total, of which 2 share a similar altitude band with EPSILON R/B.