H-1 R/B

H-1 R/B is a spent rocket body associated with Japan, launched on 1990-02-07 from TNSTA on the Mos-1b launch. With over 36 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Low Earth Orbit (LEO) at altitudes between 890 km and 1,605 km with an inclination of 99.1°. It travels at approximately 26,040 km/h (7.23 km/s), completing one full orbit every 110 minutes — that’s roughly 13.04 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is thousands of years. Spent rocket bodies like H-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.

H-1 R/B orbits at an average altitude of 1,248 km in the uppermost reaches of Low Earth Orbit. At this altitude, orbital decay is effectively zero without active deorbiting, and coverage footprints are significantly larger than lower LEO, though at the cost of higher latency. Within ±50 km of H-1 R/B’s average altitude, there are currently 359 active payloads and 304 tracked debris or rocket body fragments — notable neighbours include ONEWEB-0008, ONEWEB-0007, ONEWEB-0006. With an inclination of 99.1°, H-1 R/B passes over latitudes between 99.1°N and 99.1°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.