Issue 118

5 Apr: The rendezvous proximity operations between Cosmos 2581 (62902) and Cosmos 2582 (62903) continued. Here is the analysis we did for the Flash on 9 Mar 2025 which details the interactions between the three satellites from 13 Feb through 7 Mar 2025. This article details what we’ve seen from 8 Mar through 6 Apr 2025. Of note, Cosmos 2582 appears to be doing all of the maneuvering while Cosmos 2581 remains in its natural orbit. For its part 2583 has conducted limited maneuvers but is believed to have released an object (cataloged as “Object F” <63330>) on 18 Mar. This article is based solely on TLE data available on Celestrak.org, reporting provided by the Joint Commercial Operations (JCO) cell and orbit visualization from Space Cockpit.

Timeline:

• 6-8 Mar: Cosmos 2581 & 2582 are separating at an approximate rate of 5 km/day. Satellites are separated by ~6.5km.
• 9 Mar: Cosmos 2581 & 2582 continue to separate, now ~18.8km apart.
• 10 Mar: Cosmos 2582 maneuvers and range to 2581 decreases to ~9.7km and closing.
• 11 Mar: Cosmos 2582 has a close approach of <2km with 2581.
• 12-15 Mar: Cosmos 2582 has periodic close approaches of <1km with 2581.
• 16 Mar: Cosmos 2582 maneuvers to increase separation with 2581. Object separation grows to >120km. Later on 16 Mar, Cosmos 2582 maneuvers again to begin closing with 2581.
• 17-19 Mar: Cosmos 2582 reduces separation with 2581 from >120km to ~3.4km.
• 20 Mar: Cosmos 2582 again maneuvers to reduce distance with 2581. JCO predicts maneuver will result in <1km RPO between the 2 satellites.
• 21- 27 Mar: Separation between Cosmos 2582 and 2581 declines from ~20.8km to ~2.2km. Cosmos 2582 continues to close with 2581.
• 28 Mar – 6 Apr: Cosmos 2582 conducts RPO with Cosmos 2582 and is continuously within 1km.

6 Apr: For over 2 years Luch (Olymp-K 1) (40258) loitered at 18° West longitude and in the vicinity of Intelsat 37E (42950). On ~26 Mar 2025, Russian space operators lowered Luch/Olymp K1’s average altitude creating an eastward 0.52° per day drift. As of 6 Apr 2025, Olymp-K 1 continues to orbit below the GEO belt. Its next intended target remains unknown.

– Olymp-K 1 decreased its average altitude ~29km on 26-27 March and then another ~10km on 31 Mar – 1 Apr. As a result, the satellite is now orbiting ~40km below Geostationary Orbit. At its new average altitude, Olymp-K 1’s orbital period is now shorter than the Earth’s rotation and the satellite is moving eastward 0.52° per day.

-As of 6 Apr 2025 Olymp-K 1 was at 13.2° West Longitude.

Background:

• Luch/Olymp launched on 28 Sep 2014 on a Proton-M SLV from Baikonur Cosmodrome.
• The name of the satellite is not precisely known. Manufacturer documents refer to it as “Olymp” or“Olymp-K” while Russian United Nations filings reference the satellite as “Luch,” which is a series of Russian “bent pipe” data relay satellites.
• During its 10 years on orbit, Luch has parked near more than a dozen commercial communications satellites for periods ranging from a few weeks to over 2 years.
• For more details on Olymp-K 1’s history, watch 2020 COMSPOC video on Luch/Olymp activities.

https://www.youtube.com/watch?v=D67dg9P3eDY

26 Mar: China launched a Long March-3B with the TianLian-2 04 (63361) data relay satellite from Xichang. According to official sources, the satellite entered the planned orbit. TianLian-2 04 joins TianLian-1 04 & 05, TianLian-2 01, 02 and 03 in Geostationary Orbit (GEO). TL-2 04 will provide global coverage for data relay and transmission services, supporting communications between the China Space Station and other Low Earth Orbit satellites and their mission control centers in China. Launch Video.

– With the addition of Tianlian-2 04 there are now 6 operational Tianlian relay satellites. This is China’s first Tianlian launch since July 2022 when it launched TL-2 03.

– The Tianlian satellites are similar to NASA’s Tracking and Data Relay Satellite network and the European Space Agency’s European Data Relay Satellite network. Overall, the Tianlian network consists of 2 first generation and 4 second generation satellites.

– The first generation of TianLian (“sky chain”) satellites were built around the DFH-3 satellite bus and were launched between 25 Apr 2008, and 6 Jul 2021 using Long March 3C rockets from Xichang.

– The second generation of Tianlian satellites are built around the DFH-4 satellite bus and have switched to the more powerful Long March 3B also launching from Xichang.

– The second generation of the satellites introduced multi-targeting ability and improved data transmission rates into the overall network.

– TL-2 uses K-band frequencies (TL-1 satellites used S-band) to enable 1.2 Gbps data transfer rates between the Chinese Space Station and ground control stations.

– The satellites make real-time communications including video possible between the ground and the Tianhe space station module, where three Shenzhou 14 astronauts are currently living and working. See video on China’s relay satellite capabilities.

– Per Andrew Jones: “Compared with Tianlian-2 (03)…(TL-2 04) features several technical upgrades, including transmission capacity and response speed. The improvements aim to meet growing domestic needs for data and TT&C while enhancing the autonomy and security of China’s second-gen relay system, according to CASC.”

– On 4 April, the spacetrack.org data showed TL-2 04 in GEO at 80°E longitude. TL-2 04 joins TL-2 02 (44076) over the Indian Ocean. TL-2 02 launched in 2019 and spent its first 2 years at 80°E. In late July 2023, Chinese operators slowly re-located TL-2 01 to its current position at 77°E.

– China now has pairs of satellites operating over Africa (TL-1 05/TL-2 03), the Indian Ocean (TL-2 02/TL-2 04), and the Western Pacific (TL-1 04/TL-2 02). See graphic. (Editor’s note: inclination shown in graphic will likely change as this was the first observation of TL-2 04 in GEO).

https://www.youtube.com/watch?v=RgaYlvvoRLghttps://www.youtube.com/watch?v=k1rXBQpTY3c

29 Mar: China launched a Long March-7A with TJS-16 (63397) from Wenchang. 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”. Launch Video.

– As of 5 Apr, TJS-16 was cataloged in GTO in the spacetrack.org space tracking catalog. However, there were unverified reports from the Joint Commercial Operations (JCO) Cell that the satellite may have been located at 152°E.

• If confirmed, this would place TJS-16 between TJS-12 (62374) launched 20 Dec 2024 at 146.5°E and TJS-1 (40892) launched 12 Sep 2015 at 155°E. The mission for TJS-12 remains unknown, while TJS-1 is a suspected “Qinshao-3” SIGINT collection satellite.
• As is the norm for TJS satellites, China released little information regarding TJS-16’s mission.

– In the past 10 years China has launched 15 TJS satellites, 10 of which were launched in just the past 4 years:

• 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-16 is only the second TJS satellite to launch on the LM-7A. TJS-10 (58204) was the only other TJS satellite to use the LM-7A. Both launched from Wenchang.

– The TJS-15 and TJS-16 have similar mission logos. TJS-15’s patch reads, “King of the West and One Who Sees All.” TJS-16’s patch reads “King of the East and One Who Sees All.” At 90.3°E TJS-15 is located 51.7° west of TJS-16.

– China’s statements regarding the mission of TJS-16 matches the statement released after TJS-15. – TJS-15 launched on a LM-3B from Xichang while TJS-16 used a LM-7A from Wenchang.

– Per Andrew Jones: “The 7A is a 60.1-meter-long, 3.35-meter-diameter kerosene and liquid oxygen launch vehicle with four side boosters…(it) is capable of delivering up to 7 metric tons of payload to GTO (in comparison the LM-3B can lift 5.5 metric tons into GTO). It features a fairing diameter of 4.2 meters…The launcher has been seen as a long-term replacement to the workhorse, hypergolic Long March 3B for launches to GEO. However, the rocket has yet to launch more than twice in a calendar year.

https://www.youtube.com/watch?v=sURqjkNY9o4

1 Apr: The latest batch of 18 Qianfan (SpaceSail) satellites is now in the spacetrack.org catalog. Qianfan 73-90 (63159-63176) are all co-planar and beginning to increase their average altitudes. The Qianfan Constellation is developed by Shanghai SpaceSail Technologies Co., Ltd. to “provide global users with low-latency, high-speed and ultra-reliable satellite broadband internet services”. This is a follow up report to the original article in the 26 Mar 2025 Integrity Flash.

– With this launch there are now 90 Qianfan satellites on orbit. Not all appear to be operational with the bulk of the problems coming from the Group 2 launch.

– Batch Updates:

• Batch 1 (launched 6 Aug 2024) : 17 of 18 satellites have raised their average altitude to 1,068.9km where they continue to operate. Qianfan 7 (60385) has not maneuvered and may be inoperable.
• Batch 2 (launched 15 Oct 2024): 15 of 18 satellites have raised their average altitudes. There is a wide variance between the operational satellites, lowest being 814km and highest at 1,062km. Three of the satellites, Qianfan 27 (61560), Qianfan 28 (61561) and Qianfan 35 (61568) have not maneuvered and may be inoperable. Qianfan 24 (61557) is questionable at 814km.
• Batch 3 (launched 5 Dec 2024): 18 of 18 satellites have raised their altitude. Qianfan 39 conducted some initial maneuvers in late-Dec and remains at 808km. Qianfan 42 last maneuvered in early-Jan 2025 and is only at 811km. The other 16 are orbiting between 913-1,069km with 9 of the satellites at 1,068-1,070km.
• Batch 4 (launched 23 Jan 2025) : 18 of 18 satellites have raised their altitude. Satellites do not appear to have settled into an operating altitude & are orbiting at average altitudes ranging from 982.6-1,057.4 kms.
• Batch 5 (launched 11 Mar 2025): Satellites only beginning to maneuver. Too early to assess operational conditions. Average altitude range is 904.3-956.8km.

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1 Apr: China launched a Long March-2D with 4 “Satellite Internet Technology Test Satellites” (63428-63431) from Jiuquan. For the first time, the Long March-2D launch vehicle used a 3.8-meter composite payload fairing. According to official sources, the satellite entered the planned orbit successfully and is “primarily used to conduct technical verification and experiments, including mobile-to-satellite broadband connections and the integration of space-ground networks”. Launch Video.

– With this launch there are now 9 Hulianwang Jishu Shiyan (satellite Internet technology test) satellites on orbit.

– All 4 satellites are co-planar with an average altitude of 450km and an inclination of 55°.

• Per Chinese social media, two of the satellites were manufactured by Galaxy Space and the other two were from the Chang Guang Satellite Technology Co.
• Previous test satellites of this family are operating at over 1,100km average altitude. They are divided into two additional orbital planes with two satellites inclined at 86.5° and three inclined at 50°. (see graphic).

– Per Andrew Jones:

• “China is already pressing ahead with two low Earth orbit megaconstellations, Guowang and Qianfan/Thousand Sails, yet the satellite Internet technology test satellite missions are continuing. These could be unrelated, or be pathfinders for new generations of satellites for these projects, and test systems such as propulsion, power, thermal control and phased array antennas.”
• “China launched three separate “high orbit” internet satellites across three launches in 2024, with the satellites operating in geostationary orbit. As with the low Earth orbit satellites, little is known about the spacecraft. The lack of publicly available information raises speculation about its potential uses, which observers speculate could include military or dual-use applications.”

31 Mar: Between 18-30 March 2025, Chinese space operators significantly increased the average altitude for 9 of 10 of their Yaogan-35 and 36 (YG-35 & YG-36) Trail1 satellites. Specifically, China raised the average altitude for the Trail1 satellites for the following triplets: YG-35 01 (49390), 35-02 (52907), 35-03 (53318), 35-04 (53526), 35-05 (53763), 36-01 (53943), 36-02 (54043), 36-03 (54374) and 36-04 (54746). Only YG-36 05 remains in formation. There were no corresponding SMA increases from either the Lead or Trail2 satellites and as a result these formations rapidly dissolved as the Trail1 satellites now are traveling slower (have a longer orbital period) relative to their Lead and Trail2 counterparts. Operating at different altitudes also affects the rate of RAAN progression and the Trail1 satellites will no longer be co-planar with their partners if they remain at different average altitudes.

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China could easily lower the Trail1 satellites to rejoin their partners at the time of their choosing. The longer this takes the greater the RAAN differential. Conversely, as we noted in the last Flash, 4 of these triplet formations seem to be having problems with their Lead satellites and a few of the Trail2 satellites have been problematic as well. There is the possibility that China has increased the average altitude of the Trail1 satellite to operate independently from their partners (which may be inoperable) to maximize the Trail1 satellites’ capabilities (specifics of which remain unknown). The coming weeks will be telling.

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The 6 remaining Yaogan triplets remaining in formation are also those most recently launched. All five sets of Yaogan-39 triplets remain in formation (all launched between Aug-Dec 2023) as does the YG-36 05 (launched Jul 2023.)

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All 5 of the orbital planes have at least 1 YG-39 triplet and one of the planes has 2 triplets (YG-39 05 and YG-36 05).

4 Apr: Newer Flash readers may not be aware that for a few months in 2022 we had Jack Anthony as a contributing author. In early 2024 I sent Jack a head’s up on what we saw with the SY-24 triplets and SJ-6 05B, and he was nice enough to give us his thoughts on what was going on, namely that satellites operating at different average altitudes have different orbital periods…or as Jack calls it, the “10 to 1 Rule.” I thought it would be a good idea to re-introduce the topic in light of the Cosmos 2581/2582 and YG-35/36 Trail1 maneuvers detailed in previous articles. I also want to recommend the following articles Jack wrote for the Flash covering the Classic Orbital Elements:

• Jack’s Astro Corner: It’s Elemental (Part I)
• Shaping up with Eccentricity (Part II)
• Inclination – The Tilted Element (Part III)
• Right Ascension of the Ascending Node (RAAN) – Let’s Do the Twist (Part IV)
• Argument of Perigee — Let’s get close with our orbit (Part V)
• How To Rendezvous With Another Satellite
• True Anomaly — “Where are we?” (Part VI)
• Applying your Orbital Element Knowledge

Many thanks to Jack for coming out of retirement to help out our Flash readers (and editor).

I’m baaaaack! Remember all those “Jack’s Astro Corner” articles I wrote? Hope so! We covered a lot of topics that can help you understand threat astrodynamics that confront us these days. The preceding “Shiyan-24A/B/C & Shijian-6 05B: A Closer Look” article gives me a chance to illustrate some astro rules of thumb. I particularly wish to look at the 24A, B and C trio “fly-by” of 6-05-B that occurred 7 – 8 January 2024. I’ll call the trio the Chasers, and the SJ 6-05-B satellite the Target for my discussion. When I watched the LSAS prepared video, I saw an opportunity to explain the 10:1 rule, plus expand on the explanation of the out of plane motion (both crosstrack and radial). This 10:1 rule of thumb is applicable to Low Earth Orbits. If you have not watched the video, please do so. Pretty cool video to learn from! Watch it several times… start and stop it and try to formulate how YOU would narrate it to a fellow US Space Force Guardian. All Guardians should seek to learn and be able to step up and be the astro hero, and say with confidence “let me explain what we are seeing here.”

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10:1 Rule: What you talking about, Jack? In his 1999 book Space Power Theory, James Oberg introduces the concept, based on his many years as a NASA Flight Controller at Johnson Space Center. Jim is an space expert of the highest order, and one of the best “explainers of astro stuff.” Here’s a pdf of the section of his book. Note he uses the term “Orbitology”, which is a term I hate, with one exception… when Jim Oberg uses it. His explanation of the 10:1 Rule is on the third page. Give it a read, in its entirety — you’ll learn a lot.

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I called upon my astro and RPO dynamo friend Jason Westphal, who leads a company named TenOne Space. Wow, Jason named his company after the 10:1 Rule! He spelled it out “TenOne.” That’s pretty cool! His team are RPO experts, and the 10:1 Rule is a key concept used by RPO mission teams as they seek to get their Chaser close to a Target (for example, getting into position to dock for servicing).

Here’s how Jason explains it:

“The majority of missions we undertake involve spacecraft rendezvous with other objects, so it seemed appropriate to name our company after the 10:1 rule. The 10:1 ratio enables us to estimate the timing for the convergence of co-elliptic drift phasing orbits. To illustrate, if we’re trailing a target spacecraft by 10 km with the objective of reaching the target inserting into a safety ellipse in close proximity after one orbit, we know our spacecraft needs to attain an orbit with a semi-major axis 1 km below that of the target to achieve the desired drift rate using the 10:1 rule.”

Let’s dive into the recent RPO situation involving the trio drifting by the Target. I want to draw you attention to what’s being shown in the video at T+ 4 to 22 seconds, as well as the three Chasers Range to Target over Time plot, at T+33 sec.

You see a lot of zig-zagging, up-down and sideways; I’ll talk about that in a second. But, did you see how the Chaser trio are in a row, moving forward relative to the Target? That’s what excited me to shout out “that’s the 10:1 Rule!” The zig-zagging ellipse is moving forward. If you study the range vs time plot, and measure the distance moved in one orbit (a sine wave cycle), you maybe be able to figure out it moves about 35 km per orbit (the orbit period is ~95.6 minutes). I grabbed the TLEs for these spacecraft from Celestrak (thank you TS Kelso), and calculated their mean orbit altitudes. My calculator tells me the Target’s mean altitude is 544 km, and the trio each is at ~540.5 km. The difference is 3.5 km. OK, get ready for the 10:1 Rule. If we multiply the 3.5 Km difference in mean altitude by 10, we get 35 km. So, since the trio is below the Target, they advance on it 35 km per orbit. See that, the 10:1 ratio works. Clark Keith (1952-2013), the RPO legend from the XSS-11 days, called it linear drift when we did it a lot in the 2005-2007 pioneering AFRL RPO experimental space mission.

They also employed a safety ellipse in their linear drift approaches to their target. More on that next. So here’s a thinking question: what if the Chaser trio was above the Target by 3.5 km? “Bueller, Bueller, Bueller…..who knows?” Of course you know: the Chaser trio would be moving back relative to the target, and at 35 km per orbit. Pretty cool stuff!

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So, what is all the zig-zagging going on? It’s a repetitive ellipse. There’s relative motion happening in both crosstrack and radial, as you can see in the video. There is an ellipse repeat going on here. China launched the trio into the orbit plane of SJ 6-05-B, but not exactly. So you are seeing the effects of their orbit having a slightly different orbit tilt (inclination) and twist (Right Ascension of the Ascending Node). Again mathematically monkeying with the TLE data, I mashed my calculator excitedly and found the trio had close alignment in inclination (I got 0.0109°) and not as close in RAAN (My estimate 0.6567°). You can see the out of plane “zig- zagging.” indicative of the offset in inclination and RAAN. There are also some big differences between the Target’s Argument of Perigee and the Chasers’. This is wise, in that it helps set up this drifting ellipse, and ensures as the Chasers go by the Target such that they don’t collide. This is the safety ellipse concept that all of us RPO enthusiasts use to keep it safe out there, as we get close to others (with permission of course). In the preceding “A Closer Look” article they talk about setting up where the Chaser is in the safety ellipse, to get the Sun in a good position for imagery. Wow, this RPO and fly-by activity requires some orbital element thinking. Do YOU know all about orbital elements? (I wrote a six part series a while ago in the Flash… a fun read. Go find it if you need a tune up.)

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Now, go explain the 10:1 rule to some General officer, or your kids, or your neighbor. They will declare YOU ARE AN ASTRO DYNAMO… maybe invite you to parties to wander around explaining astro! I hope you enjoyed my “I’m baaaack” return, and sharpened your astrodynamics understanding and awesomeness. Thank you, Jason Westphal of TenOne Space, and Jim Oberg, NASA mission control pioneer and astro “explainer of stuff.” Stay awesome for America in space!

Comparing Images of the Sombrero Galaxy: mid-infrared light (top) and visible light (bottom)
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Footprints on Mars: Opportunity Leaves its Mark
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China Announces Major Military Exercises IVO Taiwan
Title “Enveloping Advance”
Caption: “The more reckless the provocation, the greater the strangulation.”
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Meteors from the Geminids shower over Xinglong Observatory, China.
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