N-1 R/B

N-1 R/B is a spent rocket body associated with Japan, launched on 1975-09-09 from Tanegashima Space Center, Japan on the ETS 1 launch. After more than 51 years in orbit, it is one of the longest-surviving objects in the space catalogue. It orbits in Low Earth Orbit (LEO) at altitudes between 969 km and 1,094 km with an inclination of 47.0°. It travels at approximately 26,417 km/h (7.34 km/s), completing one full orbit every 106 minutes — that’s roughly 13.61 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~500–1,000 years. Spent rocket bodies like N-1 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.

N-1 R/B orbits at an average altitude of 1,032 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 N-1 R/B’s average altitude, there are currently 359 active payloads and 762 tracked debris or rocket body fragments — notable neighbours include ONEWEB-0041. With an inclination of 47.0°, N-1 R/B passes over latitudes between 47.0°N and 47.0°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 208 active satellites in total, of which 7 share a similar altitude band with N-1 R/B.