ALOS-4

ALOS-4 is an active satellite operated by Japan, launched on 2024-07-01 from TNSTA. It orbits in Low Earth Orbit (LEO) at altitudes between 630 km and 632 km with an inclination of 97.9°. It travels at approximately 27,162 km/h (7.54 km/s), completing one full orbit every 97 minutes — that’s roughly 14.79 orbits per day. Its near-polar, sun-synchronous orbit means it passes over any given point on Earth at approximately the same local solar time, ideal for consistent Earth observation lighting conditions. 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 ~10–25 years. Orbital Radar tracks ALOS-4 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

ALOS-4 orbits at an average altitude of 631 km in a sun-synchronous orbit (SSO), a specialised subset of LEO where the orbital plane precesses to maintain a constant angle relative to the Sun. This provides consistent lighting conditions on every pass — essential for Earth observation, weather monitoring and environmental science. Within ±50 km of ALOS-4’s average altitude, there are currently 790 active payloads and 843 tracked debris or rocket body fragments — notable neighbours include ONEWEB-0050. With an inclination of 97.9°, ALOS-4 passes over latitudes between 97.9°N and 97.9°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 189 active satellites in total, of which 23 share a similar altitude band with ALOS-4.