An Analysis of Precise Positioning and Accuracy of the CE-3 Lunarlander Soft Landing

In December, 2013, the Chinese lunar lander Chang'E-3 made a soft landing on the Moon successfully. Its precision positioning is a basic requirement in the analysis of scientific data. In this paper, the modeling of the precise observation equation and the statistical positioning method are first described briefly. Second, using the limited tracking data of the lander, the statistical positioning of the lander was performed and the positioning accuracy analyzed by three different methods. The results indicate that the determined altitude of the lander was approximately 4.5 m different from the latest lunar topographical model. Compared with the lander location observed from the lunar reconnaissance orbiter camera, there is a deviation less than 100 m in the three dimensions. We subsequeently analyze the positioning ability under current tracking conditions using the covariance analysis theory. These results show that the systematic error in the ranging data was the main limiting factor that restricts lander positioning accuracy, and an accuracy of 10 m positioning solution may be obtained if this bias is removed.