Issue 127

16 Aug: China conducted significant plane change maneuvers with the docked SJ-21/25 (49330 & 62485) satellites. The 2 spacecraft have presumably been docked since 2 July 2025 when they became indistinguishable from terrestrial based space domain awareness sensors (optical, radar and signal based). The pair made minor maneuvers from 2-7 Aug, then from 8 – 15 August, Chinese space operators conducted several plane-changing maneuvers which resulted in a 6° reduction of the spacecraft’s inclination and a significant change in RAAN as well. Such maneuvers are highly fuel/energy intensive (see next article) and very rare.

– Maneuver Timeline (based on TLE values for SJ-21 as they appear more current than that of SJ-25…I suspect having two objects docked is proving problematic for cataloging):

• 8 Aug (starting condition): Inclination = 10.4° SMA = 35,794.4km
• 9 Aug (test maneuvers?): Inclination = 9.8° (-0.6) SMA = 35,790.8 (-3.8km)
• 11-12 Aug (big move): Inclination = 4.4° (-5.4°) SMA = 35,759 (-32km)
• 14-15 Aug (clean up): Inclination = 4.4° (no change) SMA = 35,783 (+24km)
• 16 Aug: No changes, SJ-21/25 are cataloged with identical orbital information. Satellites are at 4.4° inclination and orbiting just 3km below the GEO belt. They are over 127° E longitude and drifting eastward at a negligible 0.03°/day.

 

Editor’s Comment: Where to start…to be clear China has not released any information regarding its refueling demonstration. They may have successfully completed refueling SJ-21 and then used SJ-25 to insert it into a new orbit with presumably a full load of propellant. I will be looking for the two satellites to either maneuver again or undock and go their separate ways. Unknown if China intends to use SJ-21 to conduct further “orbital debris mitigation” experiments. If so, it would make sense to release SJ-21 in a near plane-match with the intended target. China also has options with SJ-25. In its current orbit it is near the same inclination as TJS-11 (4.6°), TJS-19 (3.9°), YG-41 (3.7°) and SJ-23 (2.9°). Unknown if any of those spacecraft are refueling capable. China could also maneuver SJ-25 independently to a new refueling target. Watch this Space as events unfold!

15 Aug: I asked Integrity ISR’s astro-wizard Jason Dean to take a look at the recent SJ-21 and SJ-25 maneuvers and give an estimate of the fuel requirements. Looking at the series of maneuvers holistically Jason calculated the energy requirements to maneuver the satellites (currently docked) from their 8 August orbit to what they were on 15 August. While we lack certain specific information for an exact calculation, here are the numbers Jason was able to deduce. Bottom line is SJ-21 and SJ-25 combined required about 332.2 m/sec of energy (fuel) to change their semi-major axis and plane (inclination and RAAN). Note the energy (fuel) requirements for the plane change maneuvers dwarfed that of the SMA change…331.8m/sec vs 0.4m/sec respectively. Thank you Jason!

4-15 Aug: China kicked its Guowang constellation deployment into high-gear and nearly doubled the constellation size in 3 weeks (going from 34 to 67 satellites). On 4 Aug, China launched its second Long March-12 (max lift ~12,000kg) from Wenchang, specifically the new Hainan Commercial Space Launch Site. The LM-12 carried 9 SatNet LEO Group 07 satellites (65106-65114), and placed the satellites into a 906x893km orbit with an inclination of 50.0°. Then on 13 Aug China launched another 10 Guowang satellites (65164-65173) on board its largest operational rocket, the LM-5B. The LM-5B successfully delivered its payload to their 86.5° inclined orbit. The additional performance of the LM-5B allowed China to launch the Group 8 satellites at an average altitude of ~1,100km which is far closer to their operational orbit of 1,169.9km reducing the need for the satellites to use their on-board propulsion. This was the fourth launch in 17 days, following the 27 Jul LM-6A and 30 Jul LM-8A launches with 5 and 9 Guowang satellites respectively. Finally, there was a failed launch of a Zhuque-2E from Jiuquan on 15 August which may have contained 4 Guowang test satellites. LM-12 launch Video. LM-5B launch Video. Zhuque-2E Launch.

– With this launch there are now 67 satellites in the operational Guowang constellation (see graphic & table next page). Additionally, China has launched 14 Guowang test satellites.

– The 4 Aug launch was just the second launch of the LM-12. The first was on 30 Nov 2024 and carried two satellites into a 50.0° inclined orbit. One of the satellites (62186) was a test satellite for the Guowang constellation.

– China is building out the Guowang constellation with orbits inclined either 50.0° or 86.5°. Currently there are 27 satellites in three 50.0° orbital planes and 40 satellites in five 86.5° orbital planes. (see graphics)

– Summary of Guowang Operational Launches

• Group 1 (16 Dec 2024): 10 sats on LM-5B. Orbit inclined 86.5°
• Group 2 (11 Feb 2025): 9 sats on LM-8A. Orbit inclined 50.0°
• Group 3 (28 Apr 2025): 10 sats on LM-5B. Orbit inclined 86.5°
• Group 4 (5 Jun 2025): 5 sats on LM-6A. Orbit inclined 86.5°
• Group 5 (27 Jul 2025): 5 sats on LM-6A. Orbit inclined 86.5°
• Group 6 (30 Jul 2025): 9 sats on LM-8A. Orbit inclined 50.0°
• Group 7 (4 Aug 2025): 9 sats on LM-12. Orbit inclined 50.0°.
• Group 8 (13 Aug 2025): 10 sats on LM-5B. Orbit inclined 86.5°

-Per Andrew Jones SpaceNews report (regarding LM-12 launch):

• A “statement from commercial satellite manufacturer and operator GalaxySpace revealed that it provided the satellites for the launch, making GalaxySpace the first private firm to supply satellites for China’s state-led Guowang constellation.”

• “GalaxySpace has previously developed stackable satellites with flexible solar wings and demonstrated Q/V/Ka‑band multiband communication payloads. It…is capable of producing more than 100 satellites of a 1,000 kg‑class per year.”
• Previously, “all Guowang satellites had been developed by either the China Academy of Space Technology (CAST) under CASC, or the Shanghai Engineering Center for Microsatellites (SECM).”

– Reaching Intended Orbits

• For the 86.5° inclined orbits (Groups 01, 03, 04 & 08) the target SMA appears to be 1,167.9km. It appears the intended RAAN separation is ~30° between planes.
• Expect the next 86.5° launch to head to the remaining 30° plane or augment the two planes with only 5 satellites. (see graphic)
• Group 1 required 109 days to reach operating altitude.
• Group 3 required only 37 days.
• As of 17 Aug, Group 4 satellites reached 1,150+km and continue to raise their SMAs.
• Group 5 satellites are in the midst of raising their altitudes. As of 17 Aug they had increased their SMA ~13-15 km and are at ~1,020km.
• Group 8 satellites are beginning at a higher orbit, ~1,100km and all 10 have begun to increase their SMA as of 16 Aug.

– For the 50.0° inclined orbits (Groups 02, 06 & 07) the target SMA appears to be 1,149.3km.

• Group 2 satellites required 77 days to reach operating altitude.
• Group 6 satellites have begun to increase their altitudes and as of 16 Aug were at ~880km average altitude.
• The Group 7 satellites currently have an average altitude of just under 900km.

• Perhaps related to the use of the LM-12 instead of the LM-8A, the Group 7 satellites are beginning their journey ~30km higher than their Group 6 counterparts.

– As of 10 Aug the Group 7 satellites have a 116° east RAAN offset with the Group 6. In turn, the Group 6 satellites have a 59.3° east RAAN offset with the Group 2 satellites. (see graphic)

• The RAAN offsets will continue to change until all satellites match their average altitudes.

10 Aug: In doing research into China’s growing pLEO Guowang constellation I kept running across the 3 “High Orbit Internet Satellites” (aka “Hulianwan Gaogui” in the Space-track.org catalog) (59069, 60327 & 61503) China launched to GEO in 2024 and wondered if there was any connection with the similarly named LEO based “Hulianwang Digui” satellites (this is the catalog name for the Guowang LEO satellites). So I did the sensible thing and reached out to Blaine Curcio (author of the China Space Monitor & friend of the Flash). Turns out the GEO satellites are very likely owned/operated by China SatNet, the very entity that is now fielding the pLEO Guowang constellation. Blaine’s evidence for the connection below (thank you!)

– Per Blaine Curcio: “I can’t prove with 100% certainty that there’s a connection between the Hulianwang Gaogui GEO satellites and SatNet, but it seems highly likely. The smoking gun…is a letter from MIIT Radio Administration Bureau to the ITU about the 77.2deg orbital slot, in which they refer to a CSCN-G02 satellite. Considering China SatNet is typically referred to as CSCN, it seems a safe bet to assume that the GEO…61503…is connected to China SatNet.”

 

Editor’s Comment: I’m certainly not a SATCOM architect, but it seems pretty clear that China deployed the GEO satellites to provide global coverage (see spaceaware.io graphic below). It remains unclear how, or even if, the GEO spacecraft could support the growing Guowang pLEO network. There may be no operational connection and the GEO satellites are there to provide old-fashioned SATCOM to global customers. Perhaps the GEO satellites could provide a relay for the pLEO satellites while they populate their constellation (currently 67 satellites of a final build out of nearly 13,000.) China appears committed to using laser inter-satellite links but might need a GEO hop in the short term. I’m reminded of China’s multi-orbital regime approach to PNT (MEO, GEO and Inclined GEO) with their Beidou constellation. Welcome other thoughts.

3-16 August: In the 3 Aug Flash it appeared Cosmos 2589 (64467) and Obj C (64527) were positioned to conduct <10km RPO through at least 8 Aug. However, Obj C maneuvered on ~3 Aug effectively terminating the RPO conditions and the objects have been slowly separating since that time. As of 16 Aug the two objects are between 55-130km apart with the distance slowly growing each orbit. There are yet no signs of either Cosmos 2589 (last maneuver 7 Jul) or Object C maneuvering to join the GEO belt. Both have apogees of 51,195km and perigees of 20,386km resulting in a highly eccentric orbit of 0.365. To join the GEO belt the satellites will need to lower apogee and raise perigee to ~35,786km. Both satellites cross the GEO belt twice per orbit, and could potentially image other satellites as they approach that orbital plane.

I hope you enjoyed XSS-11 Part 2, and of course Part 1. Here’s Part 3 that will summarize the accomplishments of XSS-11 during its on-orbit activity April 2005 to December 2006. XSS-11 was America’s first small satellite adventure into the world of RPO-it was a learning experience, and a confidence builder. Speaking of great space experimentation, I wish AFRL and their partners good luck as they have just commenced the NTS3 space mission to explore the future of position, navigation and timing.

 

BOTTOMLINE UP FRONT. XSS-11 was launched into an 860 Km circular orbit inclined at 98.8 degrees on 11 April 2005 from Vandenberg AFB in California using a Minotaur-IV rocket. The team carefully activated and conducted early orbit checkout operations through May 2005. Then it was time to “dance” with the Minotaur upper stage which remaining in the same orbit plane as the XSS-11 spacecraft. By “dance,” I mean conduct RPO experimentation. From June 2005 to April 2006 the team got into a rhythm via a 5-day week of planning, executing and then digesting what was learned and then doing it again the next week. I will explain this next but let me get you through the mission and summarize their RPO experiments “box score” of what they did. I should note here that after almost a year of RPO activity with the Minotaur upper stage the team executed orbital maneuvers to change the right ascension of the ascending node (RAAN), leaving the upper stage behind and drifting the XSS-11 orbit plane to visit a derelict space object they were OK’ed to visit. That took about 4 months. As you know, to change orbit plane can be a very propulsive expensive deal (see Jason’s numbers in the SJ-21/25 article.) But by changing the semi-major axis they were able to slowly drift the plane to realign with their next partner in RPO with minimal fuel expenditure. After 2 months of that they prepared to end the mission by lowering the orbit to facilitate decay and deorbit and acting to safe and deactivate systems on the spacecraft. That takes us to December 2006 when it was lights out. It took about 5 years for the Earth’s atmosphere to grab onto and bring this mighty “dishwasher” sized spacecraft into the upper atmosphere to burn up.

 

THE BOX SCORE OF AMAZING RPO ACCOMPLISHMENTS I made a table summarizing the RPO techniques they tried, demonstrated and learned as they attempted and accomplished them. They worked well within 1 Km of the upper stage, sometimes within 100 meters. Each time a tremendous effort was mounted to plan, simulate and attempt a specific goal. Sometimes it was fraught with challenges, and other times it worked fine. Such is space experimentation, it’s “like a box of chocolates, you never know what you are going to get.” (using my Forrest Gump voice). Well, actually with planning and simulation and such you can have a good idea of what you’ll get. As Clark would say “let’s run the numbers before we try.” If it’s a glitch or surprise, work it! Learn! Here’s the summary.

 

A WEEK IN THE LIFE OF XSS-11. I spoke with several veterans of the mission and those deeply involved with mission operations spoke about the weekly tempo. My friend Clark Keith shared many stories about the tempo the team stayed in. A typical week started with XSS-11 in a Staging orbit. By that I mean it was not cozied up to its Minotaur upper stage RPO partner. As I said, both spacecraft shared an 860 Km orbit inclined at 98 degrees and stayed relatively synched up in right ascension of ascending node and inclination. With a plan in mind, the XSS-11 team commanded their spaceship to execute delta V’s to start XSS-11 on a course to close the distance with their awaiting target (again, just using the term I’ve always used). Clark was encouraged to not use Chaser and Target, I think that irritated him, but he complied and I’ll say he came up with the Chaser being called “Doing Object” and the Target as “Recipient Object.” XSS-11 made 14 or so orbits per day, about a 100-minute orbit period. To depart the staging area and head for the Minotaur, a little delta-V would shift the closure rate and bring it on a course to meet up with the Minotaur upper stage. As they got closer the Space Command folks in Cheyenne Mountain would share their perspectives as to “where you both are” from an orbit determination sense and of course XSS-11 had a beacon to help the AFSCN get a good orbit fix. Soon, delta V’s would be executed to set up the RPO objective. These were small burns and at times the ops team had to tweak the propulsion system tank pressure to get a tiny burn, very precise throttle adjustments. That proved to be a challenge, but they made it all work. Sometimes they would “fly-by” and use the XSS-11 LIDAR and cameras to get an image or see how the system was behaving. Here’s a photo of the upper stage from XSS-11.

Never boring and always a step forward. Other times they would set up a natural motion circumnavigation (NMC), or as some folks called it a “football” orbit. OK, let’s hear a cool XSS-11 story courtesy of Mike Drews of Lockheed-Martin. He was LM’s RPO Leader and resonated with Clark and others as they explored RPO with XSS-11.

A key objective in the XSS-11 on orbit activity was to establish a natural motion circumnavigation (NMC) relative motion trajectory around the Minotaur upper stage. For those of you involved in RPO, you’ll recognize the term NMC. “It’s a household word in the RPO business” (again, using my Forrest Gump voice). Guess what? The NMC term was created in the XSS-11 program. No kidding. Here’s the story. From Mike’s account, the Draper Lab folks called the NMC pattern the “football orbit,” after all it was somewhat shaped like the planar view of an (American) football. Mike felt a better name for the “football” orbit was needed, more descriptive. Mike proposed “Natural” Motion Circumnavigation. Here’s a simple illustration of the NMC, in this case a 5km x 10 Km NMC (that happens to be shaped like a football I guess). To enter a NMC a radial delta V is what’s needed and the NMC pattern commences. Here’s my drawing and thank you Mike for your NMC idea!

Sometimes the NMC drifted as intended and others times it needed to be stopped so they could execute proximity ops with the upper stage, loiter! My drawing is a much larger NMC than what XSS-11 routinely did. The key was to get the teeny weenie thrust necessary stop the drift. The spacecraft was equipped with a pressurized propulsion system that allowed the system to scale impulse to very small burns for precise RPO maneuvering. So you might say they had to dial it down. This helped to eliminate drift when it was not desired or get the slow drift for a NMC fly-by or hold the NMC in the vicinity of the upper stage being circumnavigated. The spacecraft team also could scale up the RPO thrusters to settle out the disturbance torque when they fired the larger thrusters for orbit changing burns. Thank you, Mike Drews and Stan Kennedy, for helping me be aware of and explain this awesomeness of capability.

There was another cool and SAFE thing they did. They would kick in some crosstrack to make a drifting ellipse safe with regard to passing the target. This prevented a V-bar crash as the XSS-11 would pass off to the side instead of through the V-bar. Today many call it the safety ellipse, “kick in” cross track at the right place and enhance safety!

 

Sometimes the NMC “stopped” relative to the target and truly did some fancy proximity operations. Hanging around, loitering, that sort of activity. Later they would attempt and successfully do station keeping. By that they would set up a position relative to the Minotaur upper stage and “hold it”…you might say they battled Kepler and made fine delta-V’s to keep in position. Never a dull day or week in the life of XSS-11. Lots of lessons learned, a few episodes or “knock it off” and back out. Safety was paramount and in the end they did not “BONK.” When the objective was attempted and completed or waved off, they would maneuver to a staging orbit and catch their breath over the weekend. For everyone on the team, it was a busy time and a time of exploring the RPO world using a small satellite. The Space Command leaders took great notice. Often detailed questions came from the stars (Generals), and they learned more about the RPO techniques and lessons learned. This RPO thing was for real and this first test flight in orbit was proving to be an eye opener and got more thinking on how this can be used for servicing spacecraft or just checking things out “out there.”

 

Whew, this brings me the end of this XSS-11 journey in three parts. I hope you enjoyed it. The XSS-11 team would receive shout outs from the American Institute of Aeronautics and Astronautics as the recipient of the 2007 Technical Achievement Award. They also got nice accolades in Popular Science magazine as a 2005 “What’s New in Aviation & Space” category. As I said in part 1, there is a lot going on “out there” in space with regard to small satellites and big ones doing RPO, and sometimes docking or grabbing. With regard to RPO, the XSS-11 team stepped up and “dared greatly” backed up with a lot of work to ensure safety and success each time they gave it a try. While I have been mentioning my friend Clark and Vern and a few others, I could fill pages with the many space pioneers who served on the XSS-11 team. They should all stand proud as they were first to step up and “dare greatly.”

 

The “This is Spinal Tap” story I shared in Part 2 got some laughter. Mike Drew’s sent me a note and provided this paragraph he wrote that I thought would explain more so the connection of that corny “mockumentary” and the XSS-11 adventure. Enjoy!

 

“Some of the team were fans of the movie ‘This is Spinal Tap‘ (came out mid-1980’s) and many folks at Octant and LM had worked both XSS-10 and XSS-11. When they were deciding on the team shirt design, quoting the famous line from that movie about guitar amps going ‘1 louder’ such that ‘these go to 11′ expression became a jovial way of describing the journey of increasing RPO capability from XSS-10 to XSS-11. Alumni fondly remember that the integrated team not only worked hard, but had fun together.”

A key objective in the XSS-11 on orbit activity was to establish a natural motion circumnavigation (NMC) relative motion trajectory around the Minotaur upper stage. For those of you involved in RPO, you’ll recognize the term NMC. “It’s a household word in the RPO business” (again, using my Forrest Gump voice). Guess what? The NMC term was created in the XSS-11 program. No kidding. Here’s the story. From Mike’s account, the Draper Lab folks called the NMC pattern the “football orbit,” after all it was somewhat shaped like the planar view of an (American) football. Mike felt a better name for the “football” orbit was needed, more descriptive. Mike proposed “Natural” Motion Circumnavigation. Here’s a simple illustration of the NMC, in this case a 5km x 10 Km NMC (that happens to be shaped like a football I guess). To enter a NMC a radial delta V is what’s needed and the NMC pattern commences. Here’s my drawing and thank you Mike for your NMC idea!