N-1 R/B

N-1 R/B is a spent rocket body associated with Japan, launched on 1978-02-16 from TNSTA on the ISS-b launch. With over 48 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Low Earth Orbit (LEO) at altitudes between 973 km and 1,209 km with an inclination of 69.4°. It travels at approximately 26,311 km/h (7.31 km/s), completing one full orbit every 107 minutes — that’s roughly 13.45 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 1,091 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 182 active payloads and 397 tracked debris or rocket body fragments — notable neighbours include ONEWEB-0041. With an inclination of 69.4°, N-1 R/B passes over latitudes between 69.4°N and 69.4°S, covering most populated land masses in both hemispheres. This mid-inclination band balances global coverage with efficient launch energy requirements. Japan operates approximately 190 active satellites in total, of which 3 share a similar altitude band with N-1 R/B.