TANSEI 3 DEB

TANSEI 3 DEB is a tracked piece of space debris attributed to Japan, launched on 1977-02-19 from Uchinoura, Japan on the MS-T3 launch. With over 49 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Medium Earth Orbit (MEO) at altitudes between 806 km and 3,743 km with an inclination of 66.3°. It travels at approximately 24,444 km/h (6.79 km/s), completing one full orbit every 2 hours 14 minutes — that’s roughly 10.79 orbits per day. Its orbital eccentricity of 0.1699 gives it a noticeably elliptical path, with significant altitude variation between perigee and apogee. As orbital debris, TANSEI 3 DEB poses a potential collision risk to operational satellites in nearby orbits and is continuously monitored by the U.S. Space Surveillance Network and other tracking systems.

TANSEI 3 DEB orbits at an average altitude of 2,275 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 TANSEI 3 DEB’s average altitude, there are currently 1 active payload and 10 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 66.3°, TANSEI 3 DEB passes over latitudes between 66.3°N and 66.3°S, covering most populated land masses in both hemispheres. This mid-inclination band balances global coverage with efficient launch energy requirements. Japan operates approximately 200 active satellites in total.