Design and implementation of GNC system of lander and ascender module of Chang’e-5 spacecraft

The lander and ascender module of Chang’e-5 spacecraft achieved China’s first lunar landing and ascent mission. The guidance, navigation, and control (GNC) system is one of the most important subsystems. To meet the weight, safety, and intelligence requirement of the mission, light-weight integration designs are implemented in the GNC system, so that a single control system could meet the mission requirement of landing, ascent, and rendezvous. Moreover, a high-rate robust optical obstacle avoidance system is applied with a hierarchical controller, and landing security is enhanced while fuel consumption is minimized. Furthermore, autonomous attitude determination on the lunar surface and orbit insertion are achieved during the lunar ascent phase, and momentum wheels are relied on to obtain good attitude stability for the spacecraft during the rendezvous phase. Finally, the GNC system has fully functional redundancy and autonomous management, which significantly increases the fault detection and isolation capabilities. Here, we present key design specifications and implementations in the GNC system of the lander and ascender module.