YAOGAN 4

YAOGAN 4 is an active satellite operated by Chinese Ministry of National Defense (China), launched on 2008-12-01 from Jiuquan, China. After 18 years in orbit, it continues to be tracked by global surveillance networks. It orbits in Low Earth Orbit (LEO) at altitudes between 608 km and 630 km with an inclination of 97.9°. It travels at approximately 27,185 km/h (7.55 km/s), completing one full orbit every 97 minutes — that’s roughly 14.83 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. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is ~10–25 years. Orbital Radar tracks YAOGAN 4 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

YAOGAN 4 orbits at an average altitude of 619 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 YAOGAN 4’s average altitude, there are currently 1,548 active payloads and 761 tracked debris or rocket body fragments — notable neighbours include ONEWEB-0050, STARLINK-3090, STARLINK-3077. This makes it one of the more crowded altitude bands, containing roughly 8.9% of all active satellites. With an inclination of 97.9°, YAOGAN 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. China operates approximately 1,219 active satellites in total, of which 134 share a similar altitude band with YAOGAN 4.