Lunar Terrain-Driven Earth Visibility Analysis for South Polar Moon-Based Observations

Deploying Moon-based sensors at the lunar south polar regions offers unprecedented opportunities for continuous Earth observation. However, previous studies have neglected the combined effects of lunar terrain and latitudinal libration on Earth visibility. This study systematically evaluates the Earth visibility conditions in the lunar south polar regions (80°S–90°S) using high-resolution Lunar Orbiter Laser Altimeter (LOLA) data and a novel visibility algorithm. Results reveal that terrain obstruction reduces Earth visibility by up to 80% in crater-rim and high-latitude regions, rendering the spherical Moon approximation inaccurate for these areas. A 14° maximum elevation angle threshold is identified for complete Earth visibility at lunar south polar regions. Optimal sites cluster near the lunar central meridian (0° longitude) in low latitudes (80°S–82.5°S), balancing extreme observation geometry and terrain occlusion effects. High-visibility areas (≥95%) are fragmented into small patches (<5 km²), with no viable sites in extreme high latitudes (>82.5°S). This letter has quantitatively characterized the impact of lunar terrain on Moon-based Earth observations, offering guidance for future Moon-based Earth observation sensor deployment and lunar base planning.