Issue 116

Gaofen-4 Conducts Inclination Station Keeping

27 Feb - 1 Mar: China made an inclination adjustment for Gaofen-4 (41194), its first Geostationary based imaging system. GF-4 is entering its 10th year on orbit (it was China's “Holiday Launch” on 28 Dec 2015) and this maneuver appears to be for station-keeping. Thank you to Robin Planell of LSAS for his assistance. -…

27 Feb – 1 Mar: China made an inclination adjustment for Gaofen-4 (41194), its first Geostationary based imaging system. GF-4 is entering its 10th year on orbit (it was China’s “Holiday Launch” on 28 Dec 2015) and this maneuver appears to be for station-keeping. Thank you to Robin Planell of LSAS for his assistance.

– Chinese space operators conducted a series of maneuvers to reduce GF-4’s inclination from 0.35° to just under 0.13°. Unlike changes in average altitude, inclination changes require significant energy and therefore are relatively expensive in terms of fuel use.

  • The Joint Commercial Operations cell (JCO) estimated the maneuver to reduce GF-4’s inclination .22° required a delta-v of 24.38 m/s. Other associated station keeping maneuvers were smaller in magnitude and required less than 1 m/s of fuel.
  • GF-4 had previously never had an inclination greater than 0.2° until 2024-2025. For its inclination maneuver in February 2024 the satellite maneuvered from 0.2° to 0.0°.

– GF-4 is China’s first GEO based imaging satellite and is believed to have a 50m resolution. From its position at 105.7°E GF-4 can keep a watchful eye on the Western Pacific and assist with tracking US aircraft carrier battle groups operating in the area.

– China has learned from GF-4 and has launched 3 other GEO based optical imaging satellites (GF-13 01, GF-13 02 and YG-41) with improving resolution. The two GF-13 satellites are believed to have 15m resolution and the YG-41 might approach 2.5m. China also operates the world’s only GEO based SAR imager (LudiTance-4 01) with a resolution of 20m.