Design and Implementation of All-Space High-Reliability Lunar Back Relay Communication System

In order to complete the mission of sampling and return from the far side of the moon, the Chang'e 6 probes need to cooperate with the relay satellite during the critical phases of landing and descent, lunar surface operations, lunar surface takeoff, and near-moon braking, which are invisible to the ground station. The relay satellite realizes the Earth-Moon relay communication function and provides forward and return measurement and control data transmission channels for the spacecraft. This paper designs and implements a high-reliability lunar far-side relay system for full-space coverage and multipath environments. The Chang'e 6 has conducted relay communication tests in the low-elevation-angle state while in orbit, expanding the available arc segment and accumulating experience for subsequent missions. The lowest elevation angle for normal execution of instructions is 9°, and no instructions are sent below 9°. This paper primarily introduces the design and implementation of the all-space high-reliability lunar far-side relay communication system for the Chang'e 6 probes.