The constellation serves to relay data from ground stations to spacecraft and rockets, most significantly China's crewed spaceflight program.
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.
The second generation system greatly improves data transmission rates and its multi-targeting ability.