Issue 124

21 June – 4 July: China continues to maneuver both SJ-21 (49330) and SJ-25 (62485) in extremely close proximity with one another and have likely made several docking attempts. The two satellites entered into merge conditions on 2 July and remain in that condition through the time of this report (4 July). The Joint Commercial Operations Cell (JCO) noted potential docking as of 2 Jul at 1108Z. Due to resolution limitations of ground based telescopes and other collection methods we will not know if SJ-25 has successfully re-fueled SJ-21 unless China releases a statement or we begin to see large maneuvers from SJ-21. Watch 30 June merge maneuvers video from s2a systems.

– Timeline (see graphics next page):

• 11 Jun: SJ-21 and SJ-25 begin RPO activity.
• 13 Jun: SJ-21 and SJ-25 operating in close proximity as to not be distinguishable by space domain awareness sensors. Merge condition exists for ~75-90 minutes.
• 14 Jun – 29 Jun: SJ-21 and SJ-25 maneuver away from one another, absolute distances between satellites varies from 5-200km.
• 30 Jun: SJ-21 and SJ-25 again appear as one object. Merge condition exists for ~6 hours.
• 1 Jul: SJ-21 and SJ-25 no longer in merge conditions and both make minor maneuvers.
• 2 Jul: SJ-21 and SJ-25 re-enter merge conditions.
• The Joint Commercial Operations Cell (JCO) has provided outstanding reporting throughout. The JCO called out the potential docking of SJ-21 and SJ-25 at 1108z on 02Jul. This matches with the equally awesome reporting from s2a systems.
• As of 4 July s2a systems noted the two objects remained in merge conditions.

3 Jul: China launched a Long March-4C with the Shiyan-28B 01 satellite Xichang. According to official sources, the satellite entered the desired orbit and “will be mainly used for space environment detection and related technical experiments”. As of 4 Jul SY-28 had yet to be entered into the space catalog and orbital information was unavailable. More to follow. Launch Video.

– This was only the second time China has launched a LM-4C from Xichang (the first time was with the lunar relay satellite Queqiao in 2018.) Observers noted the slow liftoff and larger fairing indicating a more massive payload.

22 Jun: China decreased the average altitude of its suspected inspector satellite, TJS-3 (43874), ~75km. The maneuver eliminated TJS-3’s 0.95°/day westward drift and the satellite is now located at 59°E longitude. After the maneuver the closest satellite to TJS-3 is China’s Beidou 11 (38091). If there are no further maneuvers from either satellite, TJS-3 will be ~68km from Beidou 11 on 6 July with optimal lighting conditions for imaging.

27 Jun: Based on orbital data it appears that at least 3 and as many as 6 of China’s 9 Yaogan-43 01 (60458-60466) satellites are no longer maintaining their orbits. As a result the previously consistent YG-43 01 formation has fallen apart as the problematic satellites have decreased their average altitudes due to orbital decay and are no longer maintaining their relative distances with the other YG-43 01 satellites. China’s Yaogan satellites are believed to be used by the Chinese military for Intelligence, Surveillance and Reconnaissance (ISR) operations.

– China launched all 9 YG-43 01 satellites into a 500km/35° orbit using a Long March 4B rocket on 3 Aug 2024. By 18 Sep 2024 China had maneuvered all 9 satellites into a formation in which the lead satellite was 30-32 minutes ahead of the final satellite in the train (see graphic). The average altitudes for all 9 satellites was ~ 496.5km with an average variance of <300m. As a result the formation remained stable with all 9 satellites staying in order (E, D, G, J, B, A, F, H, C) and maintaining their relative distance from one another.

-YG-43 01 remained in stable configuration until mid-March 2025 (almost exactly 6 months post launch). Beginning on 12 March China began to vary the maneuvering for several of the satellites.

-Maneuver Summary (graphs on following pages):

• The Good: China continues to maintain the orbits for 3 of the YG-43 01 satellites: 1) C (60460); 2) F (60463); and 3) H (60465). All continue to maintain their average altitudes of 497km and are regularly maneuvering (at least one maneuver per month).
• The Questionable: There are 3 satellites which have not maneuvered in over a month and are now orbiting below their historical average altitudes: 1) A (60458) last maneuver was 1 May 2025 and SMA is now 491.6km; 2) E (60462) had a maneuver gap from 17 Apr – 22 May in which its SMA dropped from 497.6km to 492.6km; it then conducted 2 maneuvers in late-May/early-Jun to increase SMA to 494km, but has not maneuvered since and SMA is now 492.1km; and 3) G (60464) which has a similar pattern as E, a maneuver gap from Mar-May, a series of SMA increases in early-May and then no maneuvers since 15 May. SMA for G is down to 492.3km.
• The Bad: Three of the YG-43 01 series have not maneuvered in over 2 months: 1) B (60459) last maneuvered on 19 Mar and its SMA has dropped to 488.1km; 2) D (60461) last maneuvered on 27 Apr and its SMA has dropped to 492.5km; and 3) J (60466) last maneuvered on 12 Mar and its SMA has dropped to 488.3km.

 

Editor’s Comment: We do not know the specific mission or capabilities of the YG-43 01 satellites. However, we do know that China launched them into a specific orbit and operated them in a well-maintained formation for 6 months. Beginning in mid-March the formation began to devolve and only 3 of the 9 satellites are now maintaining their relative positions with one another. If China had been using inter-satellite links to cross-cue between the 9 satellites, that capability is now sporadic at best as 6 of the 9 satellites have shorter orbital periods and are now lapping the 3 satellites maintaining their 497km average altitudes. As we’ve discussed before, operating at different average altitudes also generates a slight difference in RAAN procession and eventually the satellites will no longer be co-planar. This has already happened with YG-43 01 as there is now a RAAN variance of 1.9° between 01B and the three nominal satellites (01C, F & H).

27 Jun: While we’re on the subject of China’s YG-43 satellites, I thought it would be interesting to take a look at the 6 YG-43 02 satellites (60945-60950) and 3 YG-43 03 satellites (61617-61619). Recall that China launched the YG-43 03 satellites into a co-planar orbit with YG-43 02 making another 9 satellite formation in Oct 2024. China has maintained the orbits for 8 of the 9 satellites and all are maintaining their relative positions with one another. For these 8 satellites the average SMA is 496.8km with an average SMA variance is just 350m. The one exception is YG-43 02A (60945) which has not maneuvered in over 70 days (last maneuver was 19 Apr 2025). From Oct 2024 – April 2025 02A had been the lead satellite for the formation. However, without maintaining its orbit 02A’s average altitude has decreased to 489.8km and it now has a shorter orbital period than the other 8 satellites and is slowly lapping the formation. 02A also has a growing RAAN offset with the formation (currently at ~0.83°) and is no longer co-planar. Without 02A in the formation the duration from Lead to Final Trail satellite has decreased from ~15-20 minutes to ~ 12-13 minutes.

26 Jun – 5 Jul: On 26 June Russia released a sub-satellite from Cosmos 2558 which the 18 Space Defense Squadron has cataloged as “Object C” (64627). Initially believed to be debris, Object C has maneuvered and is undoubtedly an active sub-satellite. Watch Video from Marco Langbroek.

Recall that Cosmos 2558 is believed to be a Nivelir inspector satellite. It was launched in Aug 2022 into a co-planar orbit with a US reconnaissance satellite USA 326. Previous Nivelir satellites, Cosmos 2519 and Cosmos 2542, also released sub-satellites. These sub-satellites (Cosmos 2521 and Cosmos 2543 respectively) eventually released a third object at high velocity. In response USSPACECOM noted that Russia had “conducted a non-destructive test of a space-based anti-satellite weapon.”

Russian space operators last conducted orbital maintenance maneuvers for Cosmos 2558 (53323) in mid-April 2025. Over the past 2.5 months the satellite has naturally lost ~10km in average altitude (from 461.1 to 451.0 km).

From 26 Jun – 3 Jul Cosmos 2558 and Obj C were separated by 70-150km. After reducing Obj C’s average altitude on 3 Jul the satellites began to separate and will continue to do so as Obj C has a shorter orbital period than Cosmos 2558. As of 5 Jul the two objects were separated by over 4,000km. Eventually Obj C will lap Cosmos 2558 and they will have another close approach.

Cosmos 2558 and Object C are nearly co-planar with a US reconnaissance satellite USA 326 (51445). With orbital information from 5 Jul for Cosmos 2558/Obj C and 3 Jul for USA 326 (see McCants Catalog) the Point of closest approach between Cosmos 2558 and USA 326 is ~50km. Object C’s point of closest approach to USA 326 is ~80km. Both objects will have a close approach with USA 326 approximately every 4 days. It is important to note that these close approaches are not a result of Russian maneuvers, but rather are just orbital mechanics at work. However, Russia did intentionally launch Cosmos 2558 into a co-planar orbit with USA 326 and for years maintained Cosmos 2558’s orbit. With the satellites nearly plane-matched Russia could reduce the point of closest approach distance for either Cosmos 2558 (assuming it is still operational) or Object C using relatively small maneuvers.

Quick Look At Nivelir Satellites and Their US Companions

Using the information from the McCants Catalog I went ahead and compared the orbits of the 3 suspected Nivelir satellites (Cosmos 2558/2576/2588) with their USA objects of interest (USA 326/314/338 respectively). Results can be found in the table below. I then asked Jack Anthony for his take on what constitutes classifying 2 objects as being co-planar…in other words how close is close enough for inclination and RAAN? Jack noted one useful metric is to determine how much energy/fuel would be required from a “chaser” spacecraft to best match its “target.” Jack then computed the energy/fuel required to match the satellites’ average altitude (thanks Jack!)

 

Based on the valued in the spacetrak.org and McCants catalogs Cosmos 2558 remains the closest match with its corresponding USA satellite. The newly launched Cosmos 2588 is second with Cosmos 2576 having the greatest plane and SMA differences with its target US satellite.

 

Editor’s Note: the dates for the latest observations in the McCants catalog are noted next to the satellite name.

3 Jul: As noted in the 23 June Flash, Russia launched an Cosmos 2589 (64467) from Plesetsk on an Angara-5 rocket equipped with a Briz-M upper-stage on 19 June. The launch placed Cosmos 2589 into a highly eccentric orbit with the apogee (the point furthest from the Earth) going well beyond the 35,786km altitude used by Geosynchronous satellites (GEO) and the perigee (the point closest to the Earth) less than 35,786km. On 26 June the 18 Space Defense Squadron (this is the team of superstars that puts together the space catalog) noted that Cosmos 2589 released a sub-satellite (Object D, 64527) on ~26 June. Both satellites have since maneuvered and remain in their unusual highly eccentric orbits.

– Timeline

• 19-26 Jun: Cosmos 2589 maintains a 51,109 x 20,270km orbit with an inclination of 1.1°.
  • Object D has yet to be detected.
  • Jim Shell noted: “Cosmos 2589 (is) in a very interesting orbit…the orbit is such that GEO is transited twice a day with each transit of GEO altitude occurring some some 1.25° further to the east with each orbit.” Watch COMSPOC Video.
• 27Jun – 28 Jun: Both Cosmos 2589 and Object D maneuver.
  • Cosmos 2589 increased both its perigee and apogee over 100km. These maneuvers decreased the orbit’s 1.25° eastward progression to ~0.2° west.
  • Object D increased its overall average altitude over 100km. However, Russia increased the apogee by over 200km while limiting the perigee increase to <15km. As a result of these maneuvers Object D now consistently crosses the GEO belt at ~62.0°E & 147.7°E for each orbit.
  • The distances between Cosmos 2589 and Object D range from ~1,100km to ~2,400km.
• 29 Jun – 3 Jul: No detected maneuvers from either satellite.

– Context

• While this is the first instance of Russia launching into this type of orbit from Plesetsk, Russia has used similar highly eccentric orbits previously. Specifically, Express-103 (45985) and Express-AMU7 (50001).
  • Per Bart Hendrickx: “Express-103 and Express-AMU7 moved from very similar super-synchronous transfer orbits to GEO in 2020/2021 and 2021/2022 (see “Orbital Focus” website). For Express-103 this took about six months and for Express-AM7 about three months. As is to be expected, there was a gradual increase in perigee and a gradual decrease in apogee. One exception was an apogee raising burn by Express-AM7 on or before January 6, 2022.”

– Cosmos 2589 is of particular interest due to its potential GEO inspector mission. As noted in the 22 June Flash, excellent research from the aforementioned Bart Hendrickx links Cosmos 2589 with the CNIIHM Insitute which has, in-turn, been linked to Russian inspection/anti-satellite programs.

– As of 5 July it remains unclear if Russia intends to follow a similar maneuver sequence with either Cosmos 2589 or Object D. The maneuvers on 27-29 June did reduce the orbits’ eccentricity while increasing perigee values, however they also increased the apogee…opposite of what is necessary to bring the spacecraft into GEO.

• Other GEO inspector satellites, such as the US GSSAP vehicles and China’s SY-12 01/02, SJ-17, SJ-23, and TJS-3, operate in or near the GEO belt and raise or lower their average altitudes to drift east or west respectively making minor orbital adjustments as their near their intended collection objects of interest to optimize lighting conditions or collect on the desired face of the target satellite.

• It is theoretically possible for Russia to conduct GEO inspection missions from Cosmos 2589 and Object D’s current orbits.
• Per Jim Shell: “Relative velocities at GEO crossing are on the order of ~1.2 km/s…At 1.2 km/s relative rates and picking a range of 50 km and assuming a bus-fixed imaging payload the required slew rate is ~1.4 deg/s — well within the bounds of a reasonable capability. Now let’s consider a bit of Rayleigh resolution criteria….considering a central wavelength of 550 nm, we are looking at a ~12 cm imaging resolution capability given a 25 cm aperture.”
• For anyone interested in more of the details regarding non-RPO satellite imaging Jim wrote a paper for the AMOS conference which you should check out.
• While theoretically possible, operating from the highly eccentric orbit brings significant operational constraints. If Russia intended to conduct some persistent collect either Cosmos 2589 or the sub-satellite would need to plane match with the object of interest, which would come at a high fuel cost.
  • Nathan Parrott & Saber Astro’s Threat Assessment dashboard modelled both an intercept and rendezvous between Cosmos 2589 and Intelsat 39 (44476), a typical Geostationary communications satellite. An intercept (think fly-by) would require ~ 56 m/s of fuel while a rendezvous (with 1° inclination change) would require a whopping 1,150 m/s.
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Editor’s Note: Not to be Captain Obvious, but we need to wait to see what happens in the coming weeks. I anticipate Russia will eventually maneuver Cosmos 2589 and Obj D into GEO but have yet to maneuver in any conclusive way. Should they desire, Russia can conduct imagery collection operations from the current orbit, however RPO with GEO objects will require prohibitive fuel expense. Another possibility is the two satellites may test inspection operations on one another (Russia did this in LEO with their Nivelir tests.) Cosmos 2589 and Object D are currently co-planar (or nearly so) and their orbits are situated to remain over the Eastern Hemisphere and in site of Russian ground control sites. Time will tell. Thank you to Nathan Parrott and Jim Shell for their collaboration and contributions!