Tag: Shijian-21

Ground-based imagery now suggests China has completed a docking and undocking of two robotic servicing satellites

10:28 am

According to ground-based imagery by the commercial company S2A, China’s Shijian-21 and Shijian-25 robotic servicing satellites appear to have completed a docking and undocking on June 13 and June 14, 2025.

China’s Shijian-21 and Shijian-25 satellites had been moving toward each other in geosynchronous orbit, around 22,236 miles (35,786 kilometers) above the equator, Spacenews reported on June 6. And now the pair appear to have had a brief first encounter, according to observations from the ground.

Optical tracking by the space situational awareness firm s2a systems shows a close approach between the two on June 14, with the pair, at times, virtually unresolvable from the other. This suggests that Shijian-21 and Shijian-25 made at least a test-run close approach and may have even performed a docking and undocking test.

You can see video of the first apparent docking here.

Shijian-21 was launched in 2021, and was used to grab a defunct Chinese geosynchronous satellite and tug it to a graveyard orbit. Shijian-25 was launched in January 2025 to test robotic servicing of satellites. These maneuvers with Shijian-21 appear to be part of those tests.

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Chinese robotic servicing satellite now approaching another Chinese servicing satellite

9:39 am

It now appears that one Chinese robotic servicing satellite, Shijian-25, is now approaching another Chinese servicing satellite, Shijian-21, and it is expected that the two will eventually dock in order to test refueling technology.

Shijian-25 was launched in January to test on-orbit refueling and mission extension technologies, while Shijian-21 was launched in October 2021.

Shijian-21 has already executed its primary mission, docking with the defunct Beidou-2 G2 navigation satellite and towing it into a graveyard orbit above GEO. It had been passively drifting westward in GEO for much of the last year, according to COMSPOC, suggesting it may have run out of fuel, but it recently initiated maneuvers taking it towards Shijian-25.

Shijian-21 has since parked at 127.5 degrees East. Now, Shijian-25 is drifting eastwards towards Shijian-21. The two satellites are in a phased orbit, meaning their key orbital elements—such as semi-major axis, eccentricity, inclination, right ascension of the ascending node and argument of perigee—are nearly identical, but remain separated by a distance along the same path. This minimizes fuel required for a future rendezvous. The pair are expected to meet June 11 at current rate of approach, though Shijian-25 will likely slow down as it closes in.

In other words, China used the older satellite to test docking and tug operations, and now plans to use the new satellite to refuel it for further operations.

Nor are these the only satellites that are maneuvering into the area. Two American military surveillance satellites have moved in, are flying in parallel, and are likely there to observe the Chinese operations.

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China begins in-orbit test of what it claims is a “space debris mitigation” satellite

9:43 am

The Space Force has now detected a second object flying next to a recently launched Chinese satellite that China claims will do an in-orbit test of a “space debris mitigation” system.

On Nov. 3 U.S. Space Force’s 18th Space Control Squadron (SPCS) catalogued a new object alongside Shijian-21 with the international designator 2021-094C. The object is noted as a rocket body and more precisely an apogee kick motor (AKM), used in some launches for a satellite to circularize and lower the inclination of its transfer orbit and enter geostationary orbit.

Apogee kick motors usually perform a final maneuver after satellite separation so as to not pose a threat to active satellites through risk of collision. However both Shijian-21 and the SJ-21 AKM are side by side in geostationary orbit.

The close proximity of the two objects strongly suggests Chinese engineers plan to use the satellite in some manner to capture the AKM in order to de-orbit it.

While China is likely testing methods for capturing and removing space debris, using this AKM, it could also be testing military technologies, such the ability to snatch working satellites it does not own from orbit. The lack of transparency can only make everyone suspicious.

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