H-3 R/B

H-3 R/B is a spent rocket body associated with Japan, launched on 2025-02-02 from TNSTA on the QZS 6 launch. As a relatively recent addition to the catalogue, its orbital elements are well-characterised. It orbits in Medium Earth Orbit (MEO) at altitudes between 285 km and 34,537 km with an inclination of 21.4°. It travels at approximately 14,738 km/h (4.09 km/s), completing one full orbit every 10 hours 9 minutes — that’s roughly 2.37 orbits per day. Its orbital eccentricity of 0.7201 gives it a noticeably elliptical path, with significant altitude variation between perigee and apogee. Spent rocket bodies like H-3 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-3 R/B orbits at an average altitude of 17,411 km in Medium Earth Orbit, the region between LEO and GEO (2,000–35,786 km). MEO’s higher altitude gives each satellite a much larger ground footprint than LEO, meaning fewer spacecraft are needed for global coverage — but signal latency is higher and radiation from the Van Allen belts is a significant design constraint. Within ±50 km of H-3 R/B’s average altitude, there are currently 2 active payloads and 12 tracked debris or rocket body fragments. This is a relatively sparse altitude band, containing less than 1% of all active satellites. With an inclination of 21.4°, H-3 R/B passes over latitudes between 21.4°N and 21.4°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 203 active satellites in total.