Lunar pole illumination and communications maps computed from GSSR elevation data

A digital elevation model of the lunar south pole was produced using Goldstone solar system RADAR (GSSR) data obtained in 2006.12 This model has 40-meter horizontal resolution and about 5-meter relative vertical accuracy. This digital elevation model was used to compute average solar illumination and Earth visibility with 100 km of the lunar south pole. The elevation data were converted into local terrain horizon masks, then converted into lunar-centric latitude and longitude coordinates. The horizon masks were compared to latitude, longitude regions bounding the maximum Sun and Earth motions relative to the moon. Estimates of Earth visibility were computed by integrating the area of the region bounding the Earth´s motion that was below the horizon mask. Solar illumination and other metrics were computed similarly. Proposed lunar south pole base sites were examined in detail, with the best site showing yearly solar power availability of 92% and direct-to-earth (DTE) communication availability of about 50%. Similar analysis of the lunar south pole used an older GSSR digital elevation model with 600-meter horizontal resolution. The paper also explores using a heliostat to reduce the photovoltaic power system mass and complexity.