Issue 131

SJ-23 Approaching Previous Turn-Around Point

9 Oct 2025: Shijian-23 (55131) is approaching its historical western boundary of 22.4° E longitude. As of 9 Oct SJ-23 was at 23.0° E and maintaining an average altitude of 35,838km (53km above GEO) resulting in a ~0.7°/day westward drift. Historically SJ-23 has reversed course between 19-22°E and I expect China will…

9 Oct 2025: Shijian-23 (55131) is approaching its historical western boundary of 22.4° E longitude. As of 9 Oct SJ-23 was at 23.0° E and maintaining an average altitude of 35,838km (53km above GEO) resulting in a ~0.7°/day westward drift. Historically SJ-23 has reversed course between 19-22°E and I expect China will decrease its SMA in the next 10 days to initiate an eastward drift. SJ-23 began traveling west on 28 Feb 2025 when it reached 172°E over the Pacific Ocean. The last time SJ-23 was this far west was July 2024.

SJ-23 has had an interesting history. China launched the satellite on 9 Jan 2023 from Wenchang using a LM-7A. The satellite immediately exhibited unusual behaviors conducting frequent maneuvers resulting in a <4km close approach with the Chinese Tianlian-1 03 satellite in Mar 2023 and another <30km close approach with Tianlian-2 02 in Oct 2023. Beginning in Jan 2024 SJ-23’s orbit has become much more predictable, drifting east for ~225 days and then repeating the pattern going west. As it travels across the GEO belt there are numerous opportunities for SJ-23 to observe other satellites with varying lighting conditions.