Abstract: During the structure design of Chang’e 5 ascender, there are difficulties such as realizing structure lightweight, payload interface precision and direction precision forecasting with high level. The top down lightweight structure design method is proposed to cut down the weight of Chang’e 5 ascender structure to 6.2% of the total mass (47.758 kg). The structure design methods including separating the compaction and precision maintenance functions and realizing high precision by gradually using two coordinates are invented, which realizes a correlative payload interface accuracy of flatness less than or equal to 0.05 mm in a 400 mm×400 mm area. The payload pointing accuracy in orbit forecast technique based on the coupling effect between structure and payload is explored, which makes calculating payload direction changes at arc second level as exactly, efficiently and rapidly as possible. The mission of China’s robotic sampling and return from lunar surface has accomplished by support of these methods, thus promoting the spacecraft structure technology development.

Key words: Lightweight, High precision, Structure design, Chang’e 5 ascender