Issue 121

China Launches 2nd Yaogan-40 Triplets

11 May: China launched a Long March-6A launch with three Yaogan-40 02A-C (63918-20) satellites from the Taiyuan Satellite Launch Center. According to official sources, the satellites entered the preset orbits and “will be used to carry out electromagnetic environment detection and related technical tests”. The…

11 May: China launched a Long March-6A launch with three Yaogan-40 02A-C (63918-20) satellites from the Taiyuan Satellite Launch Center. According to official sources, the satellites entered the preset orbits and “will be used to carry out electromagnetic environment detection and related technical tests”. The satellites launched into the same 86.0° inclination as the YG-40 01A-C triplets (57830-32). This inclination will allow China to monitor the Arctic and Antarctic regions. The two sets of triplets are not co-planar as the YG-40 02 satellites are offset ~72° west of YG-40 01. As of 18 May 25 the YG-40 02 triplets had begun to maneuver to establish their equilateral triangle formation. This formation indicates a likely radio frequency detection and geolocation mission. Launch Video.

-To form the equilateral triangle formation China will likely operate 2 of the satellites at an increased average altitude than the third satellite for a period of time to create the desired RAAN offset. When that has been achieved, China will maneuver the satellites to the same average altitude.

  • Per Orbital Focus: “The effect of having satellites orbit at two slightly different orbit heights is that the two orbit planes move at different rates with the lower orbit moving faster. By the time the three satellites come together, the orbit of the singleton will have moved to the east of the pair at the higher altitude. “
  • The YG-43 02 satellites appear to be following the same deployment pattern as YG-40 01. Two of the satellites (A & B) have increased their average altitudes equally while YG-43 02C has decreased its SMA from 802 to 78.3km beginning on 15 May.
  • For YG-40-01 only one satellite maneuvered to create the formation. The singleton, YG-40-01C, increased its altitude to match YG-40A & B. (see graphic)
  • YG-40 spent 60 days to complete its maneuvers and begin operating in formation.
  • The YG-40 02 will likely increase their average altitude to ~850km to match that of YG-40 01. As of 19 May 2025 they had only begun their post-launch maneuvering and were at ~806km.

-Comparing with China’s YG-31 Triplets

  • China also operates 4 sets of Yaogan-31 triplets. These satellites also orbit in equilateral triangle formation, however they are in a 65° inclined orbit. They are also at a higher average altitude of 1,089.2km.
  • In the case of YG-31 02 A/B/C (47532, 47533, 47536), all three satellites maneuvered, the pair lowered their altitude initially and then increased their altitude. After initially raising its altitude, the singleton decreased its orbit to match the pair. As a result, YG-31 took about half the time of YG-40 01 to complete its maneuvers and begin orbiting in formation. (see graphic)

Editor’s Note: The YG-40 02 maneuvers will play out over the coming weeks, only then will we be able to confirm the techniques China has used to place the satellites into the desired formation. Stay tuned!