Issue 119

10 Apr: China launched a Long March-3B with TJS-17 (King of the North) (63524) from Xichang. According to official sources, the satellite has entered the planned orbit and will be “mainly used to verify multi-band and high-speed satellite communication technology” which is identical to the description provided for TJS-15 (King of the West) (63157) and TJS-16 (King of the East) (63397). Launch Video.

On 17 Apr the Joint Commercial Operations cell (JCO) noted TJS-17 had parked in GEO at 152.74 E longitude with a drift rate of 0.01 E deg/day. At this location, TJS-17 is only 0.24° east (171 km) of TJS-16 which is located at 152.50°E longitude.

• Placing 2 TJS satellites in proximity is unusual. We did see TJS-3 and TJS-10 operate within ~50km of one another for a year following TJS-10’s launch in December 2023. After a year of testing TJS-3 eventually maneuvered and is no longer in the vicinity of TJS-10.
• Of the remaining TJS satellites the closest pairing is between TJS-16 and TJS-1 (40892). Separation between these two satellites is ~2,000km.
• Orbital information is not yet available via space-track.org. Comparing the orbital parameters between TJS-16 and -17 may (or may not) yield clues as to their mission/relationship.

– Both TJS-15 & 17 were observed releasing a secondary object (believed to be an apogee kick motor ) in GEO. There was no such object released for TJS-16.

• TJS-15 and -17 both launched on a LM-3B from Xichang while TJS-16 used a LM-7A from Wenchang.
• I suspect because China used the older/slightly less capable LM-3B they likely needed an AKM to reach the desired orbit. Because TJS-16 used the more capable LM-7A it was able to reach its intended orbit without the assistance of an AKM.
  • The LM-3B can deliver up to 5,500 kg (12,100 pounds) to GTO, while the LM-7A is capable of delivering up to 7,000 kg (15,000 pounds) to GTO. Wenchang southern location also makes it a more favorable launch site for delivering satellites to GTO/GEO.

– Then there are those amazing mission patches. Per Andrew Jones: “The TJS-17 mission patch from SAST depicts the King of the North, one of the Four Heavenly Kings; a set of Buddhist deities each guarding one cardinal direction of the world. The TJS-15 and TJS-16 mission patches depicted the King of the West and King of the East, respectively. This hints at a possible forthcoming TJS mission to complete the celestial quartet.”

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https://www.youtube.com/watch?v=go8PZ7sFaiM





We’ll see if the trend continues if/when there’s a “King of the South” TJS-18 launch. Along with launch vehicle selection it will also be interesting to see if TJS-18 settles near TJS-15 to form a second pairing of TJS satellites.
TJS Summary

– In the past 10 years China has launched 16 TJS satellites, 11 of which were launched in just the past 4 years. 2025 is shaping up to be a year of unprecedented activity for the TJS family. TJS-17 is the 4th TJS launch for the first half of 2025:

• 2015 (1): TJS-1 (suspected SIGINT)
• 2016 (0): No Launches
• 2017 (1): TJS-2 (suspected Missile Warning)
• 2018 (1): TJS-3 (suspected satellite inspection)
• 2019 (1): TJS-4 (suspected SIGINT)
• 2020 (1): TJS-5 (suspected Missile Warning)
• 2021 (3): TJS-6 (suspected Missile Warning), TJS-7 (Unknown), & TJS-9 (suspected SIGINT)
• 2022 (0): No Launches
• 2023 (1): TJS-10 (unknown)
• 2024 (3): TJS-11 (unknown), TJS-12 (unknown), TJS-13 (HEO, suspected Missile Warning)
• 2025 (3): TJS-14 (unknown), TJS-15 (unknown), TJS-16 (unknown), TJS-17 (unknown)

18 Apr: China launched Long March-6A with six Shiyan-27 satellites (SY-27 01~06, 63599-63604) from Taiyuan. According to official sources, the satellites “will be mainly used for space environment exploration and related technology tests”. The 6 satellites are currently grouped closely with one another, time will tell if China plans to orbit them in formation. The satellites are nearly co-planar with Shiyan-6 03 (48157) which China launched in 2021.

Launch Video.

– All 6 satellites are orbiting at an average altitude of ~1,000km and an inclination of 99.7°.

-China left the LM-6A upperstage in an 834 x 990 km orbit at an inclination of 99.7°. The object joins a growing number of large/non-maneuverable debris circling the Earth at 800-900km (see LEOLabs graphic).

– Per Andrew Jones: “SAST stated that Friday’s launch was the first time the Long March 6A used ‘multi-satellite wall-mounted deployment,’ indicating that satellites were mounted around a central load-bearing structure, rather than being stacked vertically. This approach brought increased challenges in terms of satellite-rocket integration, according to SAST.”

– Beyond the launch mounting, China released little information regarding the 6 satellites. Their official statement is very similar to the one they released after the launch of Shiyan-06 03 on 8 April 2021.

-The SY-27 and SY-06 03 orbits are also very similar. SY-06 03 is orbiting slightly lower, at an average altitude of 974km and is inclined 99.5°. SY-06 03 has a RAAN offset of only ~1° compared with the SY-27 satellites.

– China did release information regarding the SY-06 03 mission.

• One of the technologies being tested on the Shiyan-06 spacecraft is a new super-black coating designed to prevent stray light from disrupting optical cameras.
• China’s National Center for Nanoscience and Technology said that the “nanocomposite” dark coating was installed on the Shiyan-06 satellite’s optical system. The dark material is designed to suppress stray light from the sun and Earth and “greatly improve the satellite optical system’s ability to detect dim targets.” The super-black material will absorb 99.6% of ultraviolet, visible, and near-infrared light…and has broad application prospects in dim target detection, interstellar navigation, infrared stealth and other fields.” Dim target detection capabilities can aid in tracking other satellites in orbit.

-The orbits of SY-27 and SY-06 03 would support testing the capabilities of SY-06 03 to image the new satellites.

https://www.youtube.com/watch?v=Ngf5Zk3giSg

20 Apr: On 16 August 2024 China launched a LM-4B with 9 “Yaogan-41” satellites on-board. The satellites went to a very familiar orbit, 35° inclined and 500km average altitude. Here’s the initial Flash article for context. After about a month China had maneuvered the satellites into a specific formation and were keeping the satellites at nearly the same average altitudes (within 500m) to maintain their relative positions with one another. A few weeks ago, I noticed this changed. Here’s what’s going on…

Chinese space operators have not maintained the SMA of 5 of the 9 Yaogan-43 01 (60458-66) satellites resulting in changing positions between the satellites and an extension of the entire 9 satellite train. Yaogan-43 01A (60458), 01B (60459), 01D (60461), 01G (60464) and 01J (60466) are now orbiting at average altitudes below 495km and ~2km lower than their other YG-43 01 satellites.

From ~11 Sep 2024 through 16 Mar 2025 the 9 YG-43 01 satellites were consistently in the same order: 1) Lead: 01E; 2) Trail1: 01D; 3) Trail2: 01G; 4) Trail3: 01J; 5) Trail4: 01B; 6) Trail5: 01A; 7) Trail6: 01F; 8) Trail7: 01H; and 9) Trail8: 01C. The average time separation between the Lead (01E) and Trail8 (01C) during this time was 31min 09sec. To maintain their relative distances all 9 satellites maintained an average altitude within ~355m of one another. From the available tracking data it appears China spent the first month (16 Aug – mid-Sep) deploying/maneuvering the satellites into the desired order and then spent the next 6 months orbiting within tight parameters, with each of the satellites maintaining its relative position to the satellite ahead and behind. The average altitude for all 9 satellites on 16 Mar 2025 was 496.6km.

The constellation began to change in mid-March as the average altitudes of YG-43 01B, 01D and 01J slid below 496km. In late-Mar/early-Apr YG-43 01A and 01G also had their average altitudes drop below the historical average. Looking at the graphs below it does not appear as if China is actively lowering the satellites, rather China appears to have stopped conducting the necessary station-keeping and the orbits are naturally decaying. The average altitudes continue to decline for all 5 (see graphs).

The order of the YG-43 01 satellites has changed significantly in the past 3 weeks with the satellites flying at lower altitudes steadily moving toward the front of the formation. As of 20 Apr 2025 the satellites are now in the following order (mover satellites in RED): 1) Lead: 01D; 2) Trail1: 01B; 3) Trail2: 01J; 4) Trail3: 01G; 5) Trail4: 01E; 6) Trail5: 01A; 7) Trail6: 01F; 8) Trail7: 01H; and 9) Trail8: 01C. The average altitude for the 5 “mover” satellites on 20 Apr 2025 was ~493.36km; the average for the other 4 satellites was 497.05km.

The time difference between the Lead and Trail8 is now over 49 minutes, up from just over 31 minutes (a 58% increase). Without additional maneuvers, satellites D/B/J/G/A will eventually lap the other satellites.

I can think of a few reasons why China may be re-arranging the YG-43 01 constellation:

• China concluded testing the original order after 6 months and are now re-arranging for further testing.
• China is creating RAAN differential between the 5 mover satellites and their counterparts and operating at different average altitudes is a fuel-efficient way to achieve this (we saw this with 7 “Trail2” YG-35/36 satellites in 2024).
• China is experiencing some anomaly on the 5 mover satellites and is currently unable to maintain their average altitudes. Kepler does the rest.

None of the changes are irreversible, but if the satellites use inter-satellite links these may be affected by the increased distances. Assuming the satellites can maneuver, China can reconstitute the constellation over a period of weeks (days if they maneuver aggressively).

I looked at the YG-43 02/03 (60945-50 & 61617-19) constellation and do not see a similar pattern. All 9 satellites continue to maintain their average altitudes within 0.5km of one another and the time separation between Lead and Trail8 remains within historical averages. Of course these satellites launched later than YG-43 01, with 6x YG-43 02 satellites launching on 3 Sep 2024 and 3x YG-43 03 satellites launching on 23 Oct 2024. The 9 satellites organized into their current order on ~8 Jan 2025. I’ll keep checking in to see if a similar situation develops at the 6 month point (so early Jun 2025).

Then & Now: Comparing YG-43 01 Constellation 14 Mar 25 vs 19 Apr 25 (spacemap42.com)

Way back in Feb 2020, the Northrup Grumman Mission Extension Vehicle (MEV)-1 (44625) docked with Intelsat 901 (26824) in a “graveyard” orbit above GEO and maneuvered the satellite back into service. 5 years later, MEV-1 support to Intelsat 901 has ended. On ~30 Mar 2025, MEV-1 began to increase its average altitude and carried along with it the Intelsat 901 satellite. Once reaching their desired orbit 414.5km above GEO, MEV-1 undocked with Intelsat 901 on 4 Apr 2025. Intelsat 901 will now be decommissioned while MEV-1 seems headed for another customer. Watch Intelsat Mission Video. Watch Northrup Grumman Docking Video.

– As of 16 Apr, MEV-1 remains in supersynchronous GEO orbit at 110°W longitude and drifting west at 5.24°/day.

– Per FCC filing, MEV-1 should be heading to Australia’s Optus D3 (35756).

– Optus D3 is currently at 156.1°E longitude. Barring any additional maneuvers from either satellite, MEV-1 will arrive at Optus D3’s location on ~04 May 2025.

– Prior to docking with Optus D3, MEV-1 will need to conduct some plane matching maneuvers to match D3’s inclination and RAAN.

• Friend of the Flash, Jim Shell, estimates MEV-1 will require at least 40 m/s of delta V in order to RPO and dock with Optus D3.
• I asked Jason Dean run through the math and estimate the fuel required to maneuver MEV-1 from its current orbit & plane match with Optus D3. He came up with a minimum delta V requirement of 45.9m/sec. See next 2 pages for the details!

– Intelsat 901’s future seems far less exciting. After operating for nearly a quarter-century the satellite could spend the next million+ years in orbit before eventually re-entering the Earth’s atmosphere.

https://www.youtube.com/watch?v=qwRXF-JkagUhttps://www.youtube.com/watch?v=pHrxDGafnV4

I thought the potential MEV-1/Optus D3 RPO provided an ideal opportunity to run through the math required to determine fuel/energy requirements to conduct such an operation. So I passed the basic orbital information to my Integrity ISR colleague Jason Dean and he did the rest! Bottom Line: MEV-1 will require ΔV (fuel) of 45.9 m/sec to plane-match and RPO with Optus D3.