Numerical verification algorithm for relative positioning accuracy between chang'e 2 and Asteroid Toutatis of 2012 Flyby

On December 13, 2012, China's Chang'e 2 Spacecraft successfully flew past No.4179 Asteroid Toutatis, and acquired a series of clear optical images concerning Toutatis. The data obtained is very important for us to be able to establish feasible methods for deep-space optical navigation. However, as the fly-by process cannot be repeated and deep-space environments cannot be tested using physical platforms on the ground, the problem concerning how to verify the correctness and accuracy of optical positioning algorithms emerges. According to the fly-by strategy of Chang'e 2 to detect Toutatis, in combination with navigation motion relationships between the spacecraft and the asteroid, such as orbit and position, and in light of actual data and problem models, the paper constructs a set of algorithms of ground numerical appraisal for relative positioning accuracy when Chang'e 2 flies past Toutatis. Through three relative positioning algorithms, conducting algorithm testing of ground numerical appraisal, which effectively appraises the positioning algorithm accuracy through numerical methods and clearly explains the sources of random error and system error, This method can be used as the basic means for ground verification of deep-space optical navigation algorithms.