Shijian-25/Shijian-21 Is on the Move!
China's refueling demonstration saga becomes more complex.
Since beginning its likely refuling in July, observable activity from Shijian-25 and Shijian-21, docked out in geostationary space (referred to as Shijian-25/Shijian-21 for the docked spacecraft combination), has been minimal. The lack of observable activity was somewhat expected for the pair, as a lack of potential energy-intensive events would be optimal to perform a refueling test.
However, around August 8th, according to s2a systems, Shijian-25/Shijian-21 was on the move from its prior position in the geostationary belt. By August 11th, it was believed that the pair performed an approximately 217.76 meters a second1 burn to reduce its orbital inclination from 10.6 degrees to 5.88 degrees2. And, on August 19th, refined analysis from COMSPOC suggests that the duo actually performed a 353.7 meters per second burn to maneuver themselves to a 4.4 degree inclination.
It is not known which of the spacecraft performed the burn. But, based on details of a system similar to Shijian-25/Shijian-21 shared at the Zhuhai Airshow in 2021, it was probably Shijian-25, as a refueling satellite is expected to approach the aft (where the engine is and likely a fueling port) of its servicing target.
With the burn having taken place after a few weeks of minimal activity, teams at agencies and enterprises working on the demonstration mission in China were likely confident in the results of a presumed refueling from Shijian-25 to Shijian-21.
As of August 23rd, Shijian-25/Shijian-21 still appear as a single object to ground telescopes.
It’s unclear why Shijian-25/Shijian-21 performed their large burn recently. A theory on why is that Shijian-21 has been refueled and has received a boost from Shijian-25 ahead of a second mission to remove space debris. Another theory, which I don’t believe myself but find interesting nonetheless, is that one part of the pair is planning to inspect a U.S. satellite from the USSF-44 mission, launched in November 2022, after undocking.
Yet again, I must stress that for proper details regarding the test, we will have to wait for official word from one of China's space agencies or enterprises, which may announce the success of the test anywhere from a few days to several weeks afterward.
Prior events in China’s refueling demonstration saga began with Shijian-25's launch from Xichang Satellite Launch Center in January, followed by several months of gradual approach toward its target, Shijian-21, in geostationary orbit above China, with USA-270 and USA-271 also flanking the duo. After an initial close approach in June lasting under two hours, the two spacecraft drifted apart to about 80 kilometers before heading back together. Lastly by July, Shijian-25 and Shijian-21 had become indistinguishable from one another.
World-leading technology?
With the tests now likely having been performed, China today probably leads in-space refueling and servicing technologies, having already demonstrated robotic satellite servicing. With that lead, China may begin refueling spacecraft currently utilizing its standard (it’s unknown how many satellites that is) and possibly begin providing it as an add-on service for countries that buy satellites from China. Additionally, the country may begin extending the operational lives of its missile detection and intelligence spacecraft.
Meanwhile in the U.S., Space Force officials have been whining to news outlets about the advancements demonstrated by Shinjian-25, alongside a possible lack of superiority in space, despite having an eyewatering budget of forty billion United States Dollars and ending support for similar demonstration missions.
Private capital is currently driving remaining American efforts (seeking emerging technology monopoly profits), with SpaceX leading the U.S. plans via a transfer of propellant using its Starship vehicle, but the vehicle has been stuck with regular failures, holding up orbital flights needed for the next major step in development, like a Starship-to-Starship propellant transfer. Behind them, Northrop Grumman is at a similar stage of development to Shijian-21, with refueling in space set to come later.
Video originally from COMSPOC_OPS on Twitter, video from Tweets cloned to YouTube for archival.
Meters per second for in-space burns refers to how fast a spacecraft changes its velocity when firing its engines.
Orbital inclination is how many degrees north or south a satellite drifts from the equator during its orbit.