1 Jan 2022: Four months after launching on 23 Oct, Shijian-21 (SJ-21) docked with a defunct Chinese satellite to drastically alter its geostationary orbit, demonstrating capabilities only previously exhibited by the United States. See Videos Event, Tracking of Event
– Shijian-21 docked with the defunct Beidou-2 G2 navigation satellite and towed it above the geostationary belt.
– SJ-21 approached the defunct Beidou-2 G2 navigation satellite in December, matching its orbit, rendezvousing with, and eventually docking with the spacecraft.
– SJ-21 performed a large burn on 22 Jan, taking the Beidou-2 G2 satellite 3,000km above the GEO belt.
– Tracking SJ-21 was not a trivial event. SJ-21 went “missing” from its orbital slot for a few hours, after performing what are known as “close proximity operations,” moving closer to Beidou-2 G2. The “gap” in observations was the result of the timing of the docking maneuver during daytime – when telescopes cannot image. ExoAnalytics tracked it down after it performed “a large maneuver” pulling the dead satellite out of GEO.
– The docking and subsequent engine burn – which was unusually large, taking it beyond the usual “graveyard” orbit of 300 km above GEO – has effectively moved Beidou-2 G2 out of harm’s way.
– SJ-21 undocked from Beidou-2 G2 on 26 Jan, leaving the defunct satellite in a disposal orbit. SJ-21 has returned to GEO.
– Beidou-2 G2 failed in orbit after its 2009 launch and drifting since 2010. Some believe it may have partially fragmented.
– Little is known about SJ-21. China unveiled a servicing satellite model by the Shanghai Academy of Spaceflight Technology (SAST) at an airshow in September 2021, described as a space fuel tanker. A model of the spacecraft featured robotic arms which could be used for attaching to another spacecraft.
– On 1 Nov 2021 (1 week after launch), SPCS cataloged a new object alongside SJ-21 with the international designator 2021-094C. The object was used for early RPO and inspection tests before SJ-21 targeted the Beidou satellite, COMSPOC tracking shows. See Video.
– SJ-21’s mission appears to be similar to that of the two Northrup Grumman Mission Extension Vehicles (MEV-1 and MEV-2).
China describes SJ-21 as a space debris mitigation satellite. Still, no details of the satellite nor its planned objectives were released by its developer, the state-owned China Aerospace Science and Technology Corporation (CASC), following its successful launch. The classified nature of the mission suggests it may have at least some military stakeholders or objectives.