SJ-21

SJ-21 is an active satellite operated by China Aerospace Science and Technology Corporation (CASC) (China), launched on 2021-10-24 from Xichang, China. It orbits in Geostationary Orbit (GEO) at altitudes between 35,578 km and 35,997 km with an inclination of 5.1°. It travels at approximately 11,070 km/h (3.07 km/s), completing one full orbit every ~24 hours (geosynchronous) — that’s roughly 1.00 orbits per day. At geostationary altitude, there is no meaningful atmospheric drag — this object will remain in orbit indefinitely unless actively deorbited. Orbital Radar tracks SJ-21 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

SJ-21 occupies geostationary orbit at approximately 35,786 km above the equator, where its orbital period matches the Earth’s 24-hour rotation. From the ground, it appears to hover over a fixed point — ideal for broadcast television, weather monitoring and wideband communications. With an inclination of 5.1°, it traces a small figure-of-eight pattern relative to the equator rather than remaining perfectly stationary, which can indicate aging stationkeeping fuel or a deliberate inclined-orbit strategy. Within ±50 km of SJ-21’s average altitude, there are currently 714 active payloads and 60 tracked debris or rocket body fragments — notable neighbours include ASTRA 1N, GOES 16, TDRS 13. China operates approximately 1,218 active satellites in total, of which 109 share a similar altitude band with SJ-21.