Tianlian

Mission

Tianlian is used to provide real-time communications between orbiting satellites and ground control stations. The Chinese tracking and data relay satellites were developed by the China Academy of Space Technology (CAST) and it is similar to the American Tracking and Data Relay Satellite System (TDRSS) in concept. The system is designed to support near-real-time communications between orbiting spacecraft and ground control, as well as complement the ground-based space tracking and telemetry stations and ships in tracking spacecraft. This is necessary because ground stations can only maintain contact with a satellite while it is overhead. Positioning multiple satellites in geostationary orbit ensures that the ground station and satellite are both always in view of at least one relay satellite, allowing for constant communication between the ground station and target satellite. The system provides data relay services for crewed Shenzhou missions, from Shenzhou 7 onwards, the Tiangong space station, and interplanetary missions. All satellites were launched from the Xichang Satellite Launch Center and operate in geostationary orbit.