Flight Control Practice of Relay Communication Service for Mars Exploration

To overcome the remote TT&C problem in Mars exploration, in which the TT&C distance reaches as far as 400 million kilometers, it is essential to exploit the relay communication technology for the Mars surface assets which is limited by energy and mass. Due to the complicated constraints of relay communication, such as TT&C availability of the orbiters and communication visibility between the orbiters and landing rovers originated by the Mars rotation, it is fundamental to investigate the Mars relay service problem, which is quite different from the earth orbit and lunar orbit relay communication. Based on the flight control requirements of Mars exploration mission, we concentrate on the engineering implementation of relay service in the practice of Mars exploration flight control. The characteristics of Mars exploration missions and the relay interface relationship between Mars orbiters and landing rovers is analyzed in detail, while the successful experience of NASA Mars relay network is also introduced. Taking into account all kinds of engineering constraints, the implementation of relay service for Mars exploration flight control is presented. The research results have been verified sufficiently and applied successfully in the flight control practice of Tianwen-1 first Mars exploration mission of our country, which can also extend to the potential need for subsequent Mars exploration missions and international cooperative Mars probes.