Issue 129

China Launches SY-29 Into GEO

5 Sep 2025: China launched a Long March-3C with a Yuanzheng-1 upper stage, with the Shiyan-29 satellite (65486) from the Xichang. According to official sources, the satellite was developed by the Innovation Academy for Microsatellites of the Chinese Academy of Sciences (IAMCAS) and uses the SECM3000 satellite platform…

5 Sep 2025: China launched a Long March-3C with a Yuanzheng-1 upper stage, with the Shiyan-29 satellite (65486) from the Xichang. According to official sources, the satellite was developed by the Innovation Academy for Microsatellites of the Chinese Academy of Sciences (IAMCAS) and uses the SECM3000 satellite platform. Shiyan-29 entered the desired orbit and “will be mainly used for space environment detection and related technical tests”. Launch Video.

– China has placed SY-29 into a very unusual and interesting orbit. The satellite is technically in super-GEO, in that its orbital period is greater than 24 hours.

– The GEO belt (the distance above the equator where the orbital period is ~24hrs) is 35,786km. SY-29 has an apogee (furthest point from the earth) of 36,570km, or 784km > GEO. SY-29’s perigee (closest point to the earth) is 35,800km, or 14km > GEO.

– Most objects in GEO are inclined <2°, SY-29 is inclined 28.5°.

– With its current orbital parameters, SY-29 is moving westward 5.4° per day.

– SY-29’s unique orbit will likely complicate efforts to characterize the satellite through Non-Earth Imaging. USA 270 and 271 are US GSSAP satellites, both are inclined at ~3.4°. China’s inspector satellites, SY-12 01/02 and SJ-23 are inclined ~3°.