Issue 130

China: SY-29 Update

27 Sep 2025: China’s Shiyan-29 satellite (65486) continues to orbit above GEO. Recall China launched SY-29 on 5 September and we noted that it was in an unusual orbit . SY-29 has an average altitude of 36,185km, which is ~400km greater than the GEO belt. As a result, SY-29 is moving westward 5.4°/day in relation to the…

27 Sep 2025: China’s Shiyan-29 satellite (65486) continues to orbit above GEO. Recall China launched SY-29 on 5 September and we noted that it was in an unusual orbit. SY-29 has an average altitude of 36,185km, which is ~400km greater than the GEO belt. As a result, SY-29 is moving westward 5.4°/day in relation to the Earth’s surface. SY-29 will be over mainland China from ~ 25 Sep – 5 Oct and I’ll be watching to see if China decreases its SMA during that time. SY-29’s inclination of 28.5° is also unusual. China has released little information regarding SY-29’s mission, saying only that the satellite was developed by the Innovation Academy for Microsatellites of the Chinese Academy of Sciences (IAMCAS) and “will be mainly used for space environment detection and related technical tests”. SY-29’s current orbit would support a GEO belt monitoring mission as the satellite would circle the Earth every 67 days. Its inclination give it the potential to monitor other GEO satellites but only for brief periods of time (no RPO if not co-planar). We’ll have to continue to monitor China’s maneuvers of SY-29 to better understand its mission (hopefully).