Objective Combination of ascender and lander and ascender of Change'E-5(CE-5) detectors successively landed on the moon successfully. The mission and landing modes of these two detectors are different, so we use different methods to determine their landing positions.
Methods The lunar positions are obtained with the combined the data from unified X-band (UXB) tracking network and very long baseline interferometry (VLBI) network. The method of joint statistical positioning is investigated to determine CE-5 combination of ascender and lander. Although data precision between the data-transmission signal and side-tone signal of differential of range(DOR)is marked, their effects on the positioning are not significant. Longer scale of observation data help improving the position precision, but the total length of 1 h satisfies the accuracy requirements.
Results The kinematic statistical method by polynomial fitting is used to determine the landing trajectory and the lunar position of CE-5 ascender, and is compared with the point positioning method. Their differences are better than 40 m. The landing moment of CE-5 ascender is also calculated to millisecond accuracy.
Conclusions Our method will provide a valuable reference for the lunar positioning of detectors in the future phase Ⅳ of Chinese lunar project.