China's Shijian-21 and Shijian-25 spacecraft have executed close-proximity operations in geostationary orbit (GEO), approximately 35,786 kilometers above Earth. This activity is a crucial step towards an anticipated on-orbit refueling test, a significant advancement in space technology.
The maneuvers, observed by S2a Systems, a Swiss space surveillance company, showed the spacecraft operating in close proximity. Shijian-25, launched in January 2025, is designed to test on-orbit refueling and mission extension technologies. Shijian-21, launched in October 2021, previously relocated a defunct satellite.
The recent operations mark the second instance of rendezvous and proximity activities between the two satellites. According to Comspoc, a space situational awareness (SSA) software company, the satellites came within a kilometer of each other on June 13, 2025, potentially docking. The mission aims to demonstrate capabilities for maintaining and prolonging the operational lifespan of satellites already in orbit.
The Shanghai Academy of Spaceflight Technology (SAST) developed both Shijian-21 and Shijian-25. The goal is to verify satellite fuel replenishment and life extension service technology. This technology could reduce costs, improve sustainability in space operations, and minimize space debris. The People's Liberation Army is also involved in developing on-orbit refueling capabilities.