HELSINKI — China’s Shijian-21 and Shijian-25 are conducting proximity operations for a second time high above the Earth as a precursor to an expected on-orbit refueling test.
Shijian-21 and Shijian-25 spacecraft, operating in geostationary orbit (GEO), approximately 35,786 km above Earth’s equator, appeared to come together June 30, according to optical ground tracking from S2a systems, a Swiss company which develops and operates customized systems for optical space surveillance worldwide.
An image of the pair shows them to be virtually unresolvable from each other, orbiting at around 128 degrees East, following a period in recent days in which the two spacecraft closed in on each other. The spacecraft may go on to complete a docking and potentially test on-orbit refueling and servicing.
Shijian-25 was launched in January to test on-orbit refueling and mission extension technologies in GEO. Meanwhile, Shijian-21 was launched in October 2021. SJ-21 towed a defunct Beidou-2 G2 navigation satellite into a graveyard orbit above GEO as its primary mission.
It is the second time SJ-21 and SJ-25 have conducted rendezvous and proximity operations, following a conjunction earlier this month.
According to space situational awareness (SSA) software company Comspoc, SJ-21 and SJ-25 “came within a kilometer of each other on June 13th and possibly docked. And by later on the 13th, they had separated. As of June 16th, the distance between them has increased, and they are currently over 120 km apart.”
In a June 17 post, Comspoc said the June 13 activity presents three potential scenarios during a roughly 90-minute window of closest approach. These are that SJ-21 and SJ-25 successfully docked during that time period; that the pair conducted a deliberate rehearsal maneuver but did not attempt docking; or SJ-21 and SJ-25 initiated a docking attempt but aborted during final approach.
Comspoc, like S2a, also tracked SJ-21 and SJ-25 as they approached each other last week.
Comspoc also noted that USA 270, a U.S. satellite and part of the Geosynchronous Space Situational Awareness Program (GSSAP), was in the vicinity. This may allow USA 270 to observe operations.
China has yet to comment on mission operations. Any statement would likely follow a successful refueling test. Tracking and analysis by SSA firms will likely provide insight into the activities as they develop.
Shijian-25 was developed and manufactured by the Shanghai Academy of Spaceflight Technology (SAST), and is to be used for “satellite fuel replenishment and life extension service technology verification,” according to a January SAST statement.
SAST also developed Shijian-21, making it a good target for China’s first on-orbit refueling test in GEO. The mission appears set on demonstrating capabilities for maintaining and prolonging the operational lifespan of satellites already in orbit. Such capabilities can reduce costs and improve sustainability in space operations, while also reducing debris.
The People’s Liberation Army is known to be working on the technology and training tools for on-orbit satellite refueling for both peacetime and wartime scenarios.
