UME 2 (ISS-B)

UME 2 (ISS-B) is an active satellite operated by Japan, launched on 1978-02-16 from TNSTA. With over 48 years in orbit, it has far exceeded many satellites’ design lifetimes. It orbits in Low Earth Orbit (LEO) at altitudes between 974 km and 1,217 km with an inclination of 69.4°. It travels at approximately 26,303 km/h (7.31 km/s), completing one full orbit every 107 minutes — that’s roughly 13.44 orbits per day. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~500–1,000 years. Orbital Radar tracks UME 2 (ISS-B) in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

UME 2 (ISS-B) occupies the mid-LEO band between 600 and 1,000 km, where atmospheric drag is minimal but radiation exposure remains low. This altitude range balances orbital longevity (decades to centuries) with reasonable ground coverage, making it popular for remote sensing constellations, scientific instruments and weather satellites. Debris concerns are significant here because objects persist far longer than in lower orbits.