HMU-SAT2

HMU-SAT2 is an active satellite operated by Japan, launched on 1998-11-20 from Baikonur, Kazakhstan. With over 28 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Low Earth Orbit (LEO) at altitudes between 374 km and 382 km with an inclination of 51.6°. It travels at approximately 27,666 km/h (7.69 km/s), completing one full orbit every 92 minutes — that’s roughly 15.63 orbits per day. Its near-circular orbit (eccentricity close to zero) means it maintains a very consistent altitude throughout each revolution. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is months to ~1 year. Orbital Radar tracks HMU-SAT2 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

HMU-SAT2 orbits at an average altitude of 378 km in the lower reaches of Low Earth Orbit, where atmospheric drag is significant and orbital lifetimes are measured in months to a few years. This is the busiest corridor in space — home to crewed spacecraft, rapid-revisit imaging satellites and the densest part of the Starlink constellation. Within ±50 km of HMU-SAT2’s average altitude, there are currently 1,312 active payloads and 57 tracked debris or rocket body fragments — notable neighbours include STARLINK-1008, STARLINK-1012, STARLINK-1020. This makes it one of the more crowded altitude bands, containing roughly 7.5% of all active satellites. With an inclination of 51.6°, HMU-SAT2 passes over latitudes between 51.6°N and 51.6°S, covering most populated land masses in both hemispheres. This mid-inclination band balances global coverage with efficient launch energy requirements. Japan operates approximately 189 active satellites in total, of which 5 share a similar altitude band with HMU-SAT2.