Issue 123

8-20 June: As predicted in the last Flash, China maneuvered both SJ-21 (49330) and SJ-25 (62485) into proximity with one another. Both satellites continue to make minor maneuvers and the satellites have ranged in separation from <1km to >100km and it is unknown if they were able to dock with one another (docking is likely required for re-fueling). Tracking the two satellites becomes more challenging once they are within 10km of one another due to resolution limitations of ground based telescopes. COMSPOC noted that the GSSAP satellite USA 270 (41744) adjusted its orbit to remain in proximity of SJ-21/25, likely in order to monitor China’s progress in conducting the world’s first on-orbit refueling in GEO. USA 271 (41645) did not adjust its orbit and is no longer in proximity. Watch COMSPOC Video of maneuvers for all 4 satellites (SJ-21/25 & USA 270/271) from 10-13 June. Also see amazing s2a systems video of close approach. Slingshot Aerospace also put together a video of the point of closest approach. China has not publicly shared any information regarding the ongoing test/demonstration. (I’m here for you guys if you’re willing).

– Per COMSPOC Reporting (current as of 17 Jun 2025):

• SHIJIAN-21 (SJ-21) and SHIJIAN-25 (SJ-25) have been engaged in RPO activity since 11 June, while USA 270 halted its previous eastward drift to position itself within the same longitude slot occupied by the SJ pair.
• On 11 June SJ-25 approached SJ-21, coming within roughly 50 km at approximately 01:21 UTC. Following this initial approach, both satellites executed several smaller maneuvers to closely align their orbital parameters, maintaining a mean longitude slot at~128°.
• SJ-21 and SJ-25 reached their closest proximity on 13 June between approximately 11:30 UTC and 13:00 UTC, after which they separated again. As of 16 June, the inter-satellite distance had increased significantly and is now greater than 100 km.
• Given the relatively short duration (~1.5 hours) of this close encounter, we (COMSPOC) have identified three potential scenarios:
  • SJ-21 and SJ-25 successfully docked during that time period;
  • SJ-21 and SJ-25 conducted a deliberate rehearsal maneuver but did not attempt docking;
  • SJ-21 and SJ-25 initiated a docking attempt but aborted during final approach.
• It remains uncertain whether an actual docking event took place; additional observations will be required to confirm their operational activities and intentions.
• USA 271 continued drifting eastwards and is no longer maintaining proximity to the SJ-21/SJ-25 satellite pair. Conversely, USA 270 has executed several maneuvers, drifting eastward and stopping within the mean longitude slot currently occupied by SJ-21 and SJ-25.

– Reporting from the Joint Commercial Operations Cell from 17-20 Jun has noted an additional 2 maneuvers from SJ-21 and 3 maneuvers from SJ-25. The intent of the maneuvers is unclear.

Editor’s Note: SJ-21 and SJ-25 remain co-planar and continue to maneuver. If necessary, Chinese space operators will be able to attempt additional docking with minor orbital adjustments. An interesting question is what will China do with both satellites post-test. Assuming SJ-25 proves itself as a capable re-fueling platform I would expect China to place the satellite into a more populated orbital plane in order to support additional satellites…this would mean reducing its current inclination from 10.5° to 0-2°. SJ-21 is an even more interesting question. With a full fuel tank will China use the satellite again for a “debris mitigation” demonstration or place it into a more popular orbital plane in order to conduct GEO monitoring/inspection (with a proven “capture/tow” capability)? Plane changes of this magnitude are VERY rare due to the fuel expenditure required…and maybe that’s the point. With refueling capability China can increase the maneuverability of other satellites equipped to dock with SJ-25, leading to previously unseen tactics.

20 Jun: China launched a Long March-3B with the ZhongXing (ChinaSat)-9C satellite from Xichang. ZhongXing (ZX)-9C is a 5.5 ton satellite designed to provide communications services for live television broadcasts for 15 years. China Satellite Communications Co Ltd will operate the satellite and has announced its intention to use ZX-9C to replace the aging ZX-9 (33051) which was launched in 2008. Assuming this is correct, China will place ZX-9C into GEO at ~92.2°E and eventually maneuver ZX-9 into a graveyard orbit. Launch Video.

22 Jun: China continues to evolve the formations of the 15 Yaogan triplets (45 satellites) it launched between 2021-2023. While none of the triplets remain in their original configuration of Lead-Trail1-Trail2, China continues to actively maintain the orbits of at least 35 of the 45 satellites.

YG-36 05 & YG-39 01-05 (6 Triplets, 18 Satellites)

• Lead/Trail1 Satellites: China is maintaining Lead and Trail1 formations for YG-36 05 and all 5 YG-39 triplets: 1) YG-36 05C/B; 2) YG-39 01C/B; 3) YG-39 02B/C; 4) YG-39 03C/B; 5) YG-39 04C/B; & 6) YG-39 05B/C). All 12 satellites are orbiting at ~515.9km with average altitude difference between the Lead and Trail1 satellites of only ~80m. As a result, the Lead-Trail1 satellites maintain their relative positions with one another. Lead is in front of the Trail1 satellite by 4-6 minutes. (see graphics next page)
• Trail2 Satellites: The 6 Trail2 satellites are also maintaining their operational orbits near their historical average of 497km. However, they are orbiting ~19km lower than their Lead/Trail1 counterparts and are not maintaining their relative position with either of these satellites (10:1 rule). Operating at different altitudes also results in developing a RAAN offset with the Lead/Trail1 satellites. As of 22 Jun the average RAAN offset between the Trail2 satellites and Lead/Trail1 satellites is ~3.9°. This is greater than the RAAN offset China deliberately established with its older triplets (about 3.6°) and I’m beginning to wonder if China will ever bring the band back together. To do so, China will need to match the average altitudes of all 3 satellites in each triplet.

 

YG-35 01-05 & YG-36 01-04 (9 Triplets, 27 Satellites)

• Lead Satellites: China has not maneuvered any of the Lead satellites in the past 3 months. The satellites are now operating at an average altitude of 468km well below their historical average of ~497km.
• Trail1 Satellites: China continues to maintain the orbits of 8 of the 9 Trail1 satellites. All 8 are operating at an average altitude of 515.3km which above their historical average of ~497km and nearly identical to the current average altitudes of the YG-36 05 and YG-39 Lead/Trail1 satellites noted above. The one exception is YG-36 02B (54043) which last increased its average altitude in March 2025 but not to the same extent as any of the other Trail1 satellites. I suspect this satellite may have suffered an anomaly. (See Graph).
• Trail2 Satellites: China continues to maintain the orbits of all 9 Trail2 satellites. 8 of the 9 are operating at their historical average altitude of 497km. The one exception is YG-35 03A (53316) which did not maneuver from 29 Jan – 11 Nov 2024 resulting in a loss of altitude from 496.3km to 431.3km (I thought it was a goner). However, China has been slowly increasing YG-35 03A’s average altitude for the past several months and it has climbed back to 465km.

 

Editor’s Comment: None of the 15 triplets are in their original formations. China continues to maintain 6 Lead/Trail1 formations. Only 6 of the 15 Lead satellites are maintaining their orbits. China is maintaining the orbits of 14 of the 15 Trail1 satellites at ~516km. China is maintaining the orbits of 14 of the 15 Trail2 satellites at ~497km.

Historical Context: Recall that for the first 2 years these satellites remained in predictable formation with one another, with one lead satellite about 5-7 minutes ahead of the first trail satellite (Trail1) which was itself about 1-3 minutes ahead of the second trail satellite (Trail2). In the 8 April Integrity Flash I noted that China appeared to be “pulling the plug” on the first 9 triplets (YG-35 01-05 & YG-36 01-04) by raising the average altitude of only the Trail1 satellites. Then in the 4 May edition, I noticed China raised the average altitudes of both the Lead and Trail1 satellites in the remaining 6 triplets without raising the average altitude of their Trail2 counterparts. As a result none of the 15 YG-35/36/39 triplets have maintained their original formations.

In the 8 Jun edition of the Flash we took a look back at Russia’s Cosmos 2519 on-orbit anti-satellite test from July 2017-June 2018. The follow up test occurred the following year with the launch of Cosmos 2542 in November 2019. Cosmos 2542 would eventually launch a sub-satellite, Cosmos 2543, which then maneuvered to place itself in a position to observe a high-value American satellite USA 245. Below is another excerpt from the most excellent Secure World Foundation (SWF) 2024 Global Counterspace Capabilities Report describing the activities of Cosmos 2542 and its sub-satellites, Cosmos 2543 & Object E from Dec 2019 – Aug 2020.

– On November 25, 2019, Russia conducted another launch of a Soyuz-2-1v from Plesetsk with an announced military payload on board. The satellite was catalogued by the US military as Cosmos 2542 (2019-079A, 44797) in a 97.9° inclination and 370 by 860 km orbit.

– The mission of the satellite as announced by Russia was to conduct space surveillance as well as Earth remote sensing. Outside experts have indicated it (was) likely the second satellite in the Nivelir 14F150 series.

– On December 6, Cosmos 2542 released a small subsatellite that was catalogued by the US military as Cosmos 2543 (2019-079D, 44835) and publicly announced by Russia.

– Cosmos 2543 remained within 2 km of Cosmos 2542 for three days before it conducted a series of maneuvers to raise its apogee to 590 km by December 16.

– Subsequent analysis by amateur observers strongly suggests that the purpose of these maneuvers was to place Cosmos 2543 in an orbit where it (could) observe a classified US intelligence satellite, USA 245 (2013-043A, 39232).

• USA 245 was launched in 2013 and believed to be the latest generation of electro-optical imagery satellite operated by the National Reconnaissance Office.

– The orbits of Cosmos 2543 and USA 245 (were) synchronized such that Cosmos 2543 came within 20 km of USA 245 several times in January 2020.

– After January 2020 Cosmos 2543 periodically came within 150 to 300 km of USA 245 while the latter (was) illuminated by the Sun (enabling Cosmos 2543 to) observe both sides of USA 245 continuously for up to a week at a time.

– The close proximity of Cosmos 2543 to USA 245 sparked concerns from the US military. General John Raymond, then Chief of Space Operations for the USSF and Commander of USSPACECOM, stated, “We view this behavior as unusual and disturbing,” and compared it to the 2017 separation of Cosmos 2523 that the US military considers to be a weapons test.

– In a response published by RIA Novosti, the Russian Foreign Ministry denied those accusations, claimed that they were part of a propaganda campaign against Moscow, and stated that Cosmos 2543 did not pose a threat to USA 245 and did not violate any norms or principles of international law.

– A few weeks later, it appears both countries made changes in their satellites’ orbits to increase the separation of the two objects.

• On March 11, 2020, hobbyist tracking showed USA 245 conducted a small maneuver to increase its distance from Cosmos 2542.
• In late April, Cosmos 2542 lowered its perigee to increase the separation and create a gradual separation in planes between the two satellites.

– Cosmos 2542 was decommissioned in May 2023 and re-entered the atmosphere on October 24, 2023.

– In June 2020, Cosmos 2543 made a series of maneuvers to place it into RPO with Cosmos 2535, including close approaches within 60 kilometers.

– A month later, the Russian Ministry of Defense issued a press report stating that the two satellites had conducted a close-up study of a domestic satellite with the help of specialized equipment on a small satellite.

– On July 15, a small piece of orbital debris was spotted in the vicinity of the two satellites that appeared to have separated from Cosmos 2543 at a relative velocity of between 140 and 186

meters per second (313 to 415 miles per hour).

– The US military catalogued the released object (Object E, 2019-079E, 45915) on July 16 in a 783 x 504 km orbit, with Cosmos 2543 still in a 617 x 603 km orbit. Jonathan McDowell noted

that the release occurred while the objects passed over Plesetsk.

– The event was similar in nature to the release of Cosmos 2523 in October 2017, and eventually, two more pieces of small debris were catalogued in proximity to the satellites.

– In a press release, USSPACECOM characterized the event as a space-based satellite weapons test and stated that the Russian satellites “displayed characteristics of a space-based weapon.”

– The head of the United Kingdom’s Space Directorate, Air Vice Marshal Harvey Smyth, also released a public statement on Twitter expressing concerns and calling on Russia to avoid further

testing.

– The following day, the Russian Ministry of Foreign Affairs again denied those claims, stating that this was part of a campaign to discredit Russia’s activities in space and that Russia was committed to the peaceful exploration and use of outer space by all states.

– Cosmos 2535 and Cosmos 2543 remained in close proximity through August 2020, and by August 13, they were joined by Cosmos 2536.

– In late September 2020, Cosmos 2535 and Cosmos 2536 were close enough that they are presumed to have docked.

– In mid-October, Cosmos 2536 separated away from Cosmos 2535 to a distance of 20 kilometers.

– Cosmos 2543 re-entered the Earth’s atmosphere August 26, 2024.