Abstract: Lunar landing and ascent represents one of the riskiest and most challenging phases in crewed lunar exploration missions, exerting a direct impact on mission success and astronaut safety. Mastering and breaking through the key technologies for crewed lunar landing and ascent formed the core of developing a safe and reliable crewed lunar lander, and further drove the overall advancement of China’s crewed spaceflight technology. First, mission requirements for crewed lunar landing and ascent were analyzed, followed by the proposal of a system scheme for China's crewed lunar lander. Based on this scheme, an in-depth analysis was conducted on the key landing and ascent technologies specific to typical crewed mission demands, including emergency rescue design, ultra-soft landing design, lunar surface stable ascent, and autonomous rapid circumlunar rendezvous. Corresponding technical approaches and solutions were put forward accordingly. A circumlunar orbit design method optimizing fuel consumption for both nominal and emergency ascent, as well as an integrated planning method for emergency ascent and rendezvous-docking adapting to multi-constraint and variable-target scenarios were proposed, effectively enabling the crew to return safely at any stage during the landing and ascent process. A multidisciplinary optimization method for descent velocity was developed, taking into account plume heating, landing impact and landing stability, which provided a design reference for achieving ultra-soft lunar landing. A thrust coordinated control method for parallel orbit control engines and a rapid engine fault diagnosis method were established, enhancing the lander’s control capability and safety during lunar ascent. Additionally, a scheme design method for autonomous rapid circumlunar rendezvous under complex scenarios and multi-constraint conditions was presented, addressing the challenges in rendezvous scheme design under resource and time limitations. This analysis of key technologies for lunar landing and ascent provides a reference for the design of crewed lunar landers, and also helps deepen the understanding of the development difficulties and risks associated with such landers.

Key words: crewed, lunar landing, lunar ascent, system design, key technology