Issue 141

Out of Formation: YG-31A/B/C Stumbles

18 Mar 2026: The Yaogan-31 A/B/C (43275, 43276, 43277) triplet has fallen out of formation. China launched the trio on 24 Feb 2021 and soon thereafter the satellites maneuvered into their isosceles triangle formation to conduct their RF detection/Geolocation (ELINT) mission. In June 2025 the satellites were maintaining…

18 Mar 2026: The Yaogan-31 A/B/C (43275, 43276, 43277) triplet has fallen out of formation. China launched the trio on 24 Feb 2021 and soon thereafter the satellites maneuvered into their isosceles triangle formation to conduct their RF detection/Geolocation (ELINT) mission. In June 2025 the satellites were maintaining this formation, however over the next 2 months this began to slowly change. YG-31C has a west RAAN offset with A & B and is normally equal distance between the two (see graphic). Between 10-15 Aug 2025 31C’s position relative to A & B began to change with C slowly falling behind the other two satellites. By 20 Sep 2025 31C had fallen completely behind 31B. China has not reversed the pattern and the satellites continue to slowly increase their distances from one another & likely not able to perform their mission. Reviewing the orbital history for all three satellites, there is no obvious failure and all remain at the same SMA (1,089.0km). It appears China has stopped maintaining the formation for unknown reasons.

YG-34 04 (56157), the imagery satellite trailing YG-31A/B/C is also no longer maintaining its relative position. All three of the other YG-31 formations remain intact.








YG-31A/B/C Formation Comparison: 18 Jun 2025 Nominal Condition (left)

18 Mar 2026 Off-Nominal (right) (saberastro.com)