By BlueShift | 2025-06-25

Two Chinese Shijian satellites are set to conduct an unprecedented refueling maneuver in geostationary orbit (GEO), a tactic that could significantly prolong the operational life of satellites and allow their operators to save billions in launch costs.

The Shijian-25 satellite is designed to refuel and service other orbiting satellites. It has been in orbit since January, when it was first launched to test orbital refueling technologies.

Meanwhile, Shijian-21 was launched in October 2021 to perform a docking maneuver and tow the now-defunct Beidou G-2 Navigation satellite above GEO.

GEO sits about 35,800km above Earth's equator. Objects in GEO appear stationary, as they are in sync with Earth's orbit. When spacecraft are moved out of GEO, they can move east or west.

Shijian-21 has been slowly drifting westward for most of the last year. Recent maneuvers saw it move toward Shijian-25 before parking at 127.5 degrees east.

Shijian-25 has initiated a movement that allows it to drift eastward toward Shijian-21.

Optical tracking on June 14 showed a close approach between the two satellites, suggesting that they made at least a test-run close approach and may have even performed a docking and undocking test. Watchers detected another close approach on June 13.

The two satellites are in a phased orbit, which occurs when two satellites have the same key orbital elements but remain separated by a distance, allowing them to traverse similar paths and minimizing the fuel required for rendezvous.

US eyes on the mission

The Shijian rendezvous is far from under the radar.

US Geosynchronous Space Situational Awareness Program assets have been in geostationary patrol for years and are now operating within proximity. USA 270 and USA 271, two surveillance satellites, have been observing the Chinese satellite's maneuvers.

In a post on X on June 9, US surveillance satellite technology provider COMSPOC noted, "USA 270 and 271 now flank SJ [Shijian]-21 and SJ-25 from the east and west -- potentially enabling favorable sun angles depending on the timing of closest approach."

In a study published by the China Aerospace Studies Institute in 2024, researchers noted that the People's Liberation Army has been preparing its satellites to conduct refueling maneuvers in both peacetime and wartime scenarios.

Satellite refueling technology raises potential dual-use concerns. The dexterity and ability to navigate for a rendezvous could be repurposed for manipulating or disabling a foreign satellite.

While the docking maneuver that is anticipated to occur between the Shijian satellites is likely for refueling purposes, it could be developed into an anti-satellite capability.

This imminent orbital refueling test represents a major milestone in space technology -- and is indicative of China's continued hardening of its space assets and infrastructure.

Meanwhile, the United States' expansive surveillance satellite infrastructure watches over this latest lunar development.