Analysis of Lunar Surface Stray Light for Moon-Based Multispectral Camera

Stray light degrades image quality and may damage the Moon-based multispectral camera. This study focuses on the effects of stray light on the lunar south pole on Earth observation in the Chang'e-8 mission. Compared with space-borne platform, the illumination conditions of Moon-based sensor are more complex, and the extent of its impact on the sensor remains unclear. In this study, we constructed a three-dimensional (3D) lunar illumination model based on the Hapke radiative transfer model and Monte Carlo ray tracing algorithm to accurately simulate illumination conditions and analyze the distribution of stray light on the lunar surface. In addition, the effects of sunlight hitting the camera lens directly and sunlight entering the sensor through diffuse reflection on Moon-based Earth observation were also analyzed. Based on this model, the working time of the Moon-based multispectral camera can be analyzed to avoid both solar intrusion and lunar nights. In addition, the impact of stray light on the sensor's entrance pupil under different work environments can also be evaluated. The results show that in the Chang'e-8 candidate landing area, solar elevation mainly affects the total radiance at the entrance pupil, while solar azimuth governs the spatial distribution of incident light. These findings provide important insights into timing constraints and optical interference, supporting observation scheduling and performance evaluation for the Chang'e-8 Moon-based Earth observation mission.