Issue 110

Time Flies: 3 Years & Counting for YG-35/36/39/42

22 Nov: Between 6 Nov 2021 and 10 Dec 2023 China conducted 15 LM-2D launches and placed 45 Yaogan satellites into 5 orbital planes (500km SMA and 35° inclination but different RAAN/twist...see graphic below). Each launch contained 3 satellites which deployed into a Lead, Trail1, Trail2 formation. Each plane had 9 of…

22 Nov: Between 6 Nov 2021 and 10 Dec 2023 China conducted 15 LM-2D launches and placed 45 Yaogan satellites into 5 orbital planes (500km SMA and 35° inclination but different RAAN/twist…see graphic below). Each launch contained 3 satellites which deployed into a Lead, Trail1, Trail2 formation. Each plane had 9 of these satellites, 3 YG-35, 3 YG-36 and 3 YG-39. Today, 13 of the 15 triplets are operating in formation.

There appear to be 3 types of formations: in-line, narrow RAAN offset, & wide RAAN offset.

  • In Line (6): 1) YG-36 05; 2) YG-39-01; 3) YG-39 02; 4) YG-39 03; 5) YG-39 04; & 6) YG-39 05
  • Narrow RAAN Offset (2): 1) YG-35 02 + YG-42 01; & 2) YG-36 01 + YG-42 02
  • Wide RAAN Offset (5): 1) YG-35 04; 2) YG-35 05; 3) YG-36 02; 4) YG-36 03; & 5) YG-36 04


– (Kind of) Fun Facts

  • On average the Lead satellite is 4 minutes and 45 seconds ahead of Trail1. On average Trail1 is 1 minute and 46 seconds ahead of Trail2.
  • In January 2023 and again in January 2024 China allowed the orbits of 7 of its Trail2 satellites to decay for ~5 months. It will be interesting to see if China does anything similar in January 2025. (see graphs below)
  • The original triplet (YG-35 01A/B/C) has fallen apart. The satellites may be functioning but they are no longer in any sort of formation. Lead satellite may be dead.
  • The other problem child seems to be Yaogan-35 03, where the Lead/Trail1 satellites continue to orbit in formation but the Trail2 satellite (53316) is no longer co-planar and is at a lower altitude and thus not able to maintain a consistent relative position with Lead/Trail1. In mid-Oct 2024 it began maintaining and then slightly increasing its altitude (apparently it’s not dead yet), but it is still orbiting ~60km below YG-35 03 Lead and Trail1 satellites.
  • Yaogan-35 03, Yaogan-36 04 and Yaogan-39 02 are nearly co-planar with the newly launched Yaogan-43 02 and 03 satellites discussed in previous article.
  • All of the in-line formation triplets were all launched after January 2023.

I know it’s a lot. Thanks for bearing with me.