N-2 R/B

N-2 R/B is a spent rocket body associated with Japan, launched on 1987-02-19 from TNSTA on the MOS-1 launch. With over 39 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Low Earth Orbit (LEO) at altitudes between 608 km and 813 km with an inclination of 97.4°. It travels at approximately 27,009 km/h (7.50 km/s), completing one full orbit every 99 minutes — that’s roughly 14.55 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 ~25–100 years. Spent rocket bodies like N-2 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-2 R/B orbits at an average altitude of 711 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 N-2 R/B’s average altitude, there are currently 258 active payloads and 1,570 tracked debris or rocket body fragments — notable neighbours include TERRA, AQUA, LANDSAT 9. With an inclination of 97.4°, N-2 R/B passes over latitudes between 97.4°N and 97.4°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. Japan operates approximately 190 active satellites in total, of which 7 share a similar altitude band with N-2 R/B.