Abstract: To optimize the control of Chang’e 5 probe, a relay time calibration and error control method is proposed to achieve the goal of synchronizing the time of multiple modules through any module with physical uplink channel. In this method, the time self flow among multiple modules is realized by time relay transfer between adjacent modules. A retrieval method of time reference device based on flight mode is proposed. Through the unified retrieval table, each device can identify the superior time reference device according to flight mode, and the autonomous time calibration of each module is realized. A distributed time transfer error control method between the bus controller (BC) and the remote unit (RT) is proposed. The BC terminal corrects the error when the time information is sent, the RT terminals control the error when the time information is received, and the accuracy of the whole system is guaranteed. The self organizing time synchronization of complex multi module spacecraft is realized by the proposed method. The effectiveness of this method has been verified by the actual flight of Chang’e 5 mission. It can provide reference for future spacecraft software design.

Key words: Multi module spacecraft, Time synchronization, Relay time calibration, Distributed transfer error control