Shanghai Academy of Spaceflight Technology (SAST)

上海航天技术研究院

Shanghai Academy of Spaceflight Technology (SAST), also known as the Eighth Academy, is one of the large research, design and production complexes of China Aerospace Science and Technology Corporation (CASC). It traces its origins to August 1961, when it was formed as the Shanghai Second Bureau of Electromechanical Industry, and adopted its current name in 1993. Headquartered in Minhang District, Shanghai, SAST develops launch vehicles, satellites, crewed-spaceflight hardware and deep-space probes, alongside tactical missiles and civilian businesses such as photovoltaics. Its launch vehicle work includes the Long March 2D, 4B, 4C, 6 and 12 families, and its satellite work includes the Fengyun meteorological series.

For the space robotics landscape, SAST matters chiefly as the developer of China's best-known on-orbit servicing spacecraft in geostationary orbit. Shijian-21, launched on a Long March 3B from Xichang on 24 October 2021 as a space debris mitigation technology test satellite, approached and docked with the defunct Beidou-2 G2 navigation satellite in late December 2021. On 22 January 2022 the pair performed a large burn that raised the dead satellite roughly 3,000 km above the GEO belt, well beyond the customary graveyard orbit about 300 km above GEO, and Shijian-21 undocked on 26 January 2022, leaving Beidou-2 G2 in a disposal orbit. The operation was observed by commercial space-tracking firms; Chinese officials released few technical details.

Its follow-on, Shijian-25, was launched in January 2025 and, according to Xinhua, is intended primarily to verify satellite fuel replenishment and life-extension service technologies. Independent trackers reported that Shijian-25 docked with Shijian-21 in GEO around late June to early July 2025, widely interpreted as an on-orbit refueling test between two satellites in geostationary orbit, and that the docked pair performed inclination-changing maneuvers. Optical observations by the Swiss company S2a Systems on 29 November 2025 showed the two spacecraft separated again. Neither the manufacturer nor the Chinese space agency has published an official account of the refueling.

SAST also has a long record in spacecraft docking hardware. Its 805th Institute, the Shanghai Institute of Aerospace Systems Engineering, spent 16 years developing the docking mechanism for China's rendezvous and docking missions, first used when Shenzhou-8 docked with Tiangong-1 in November 2011 and described by the institute as the foundation for later space station work. In deep space, SAST teams contributed to the Chang'e-3 and Chang'e-4 probes and developed the Chang'e-5 orbiter and the Tianwen-1 Mars orbiter. SAST is also a listed partner of the Hong Kong Space Robotics and Energy Centre, which is developing the Hong Kong Operation Robot, a dual-arm lunar surface robot for the Chang'e-8 mission.

As a unit of state-owned CASC, SAST does not publish commercial catalogues for its servicing spacecraft, and capability details for Shijian-21 and Shijian-25, including whether robotic arms or other capture devices were used, remain unconfirmed in official sources.