Persistently illuminated regions at the lunar poles: Ideal sites for future exploration

The Lunar Reconnaissance Orbiter Camera (LROC) provides multi-temporal and high resolution imaging of the north and south polar regions. These images delimit illuminated areas from those in shadow, and are used to analyze the illumination environment of the polar regions over the course of a lunar year. The Wide Angle Camera (WAC) provides repeat imaging of the north and south pole at a frequency of roughly 2 h with a ground sampling distance of 100 m. The LROC Narrow Angle Camera (NAC) acquires images with a ground sampling distance of 0.5–2.0 m providing the means to construct high resolution maps that reveal illuminated terrain under varying lighting conditions. With the multi-temporal coverage provided by the WAC and the high resolution images from the NAC, the LROC dataset enables a more comprehensive analysis of the illumination conditions near the lunar poles than any previous image based dataset. Furthermore, these images are used to validate previously published numerical models that simulate polar illumination conditions. From our analysis of the LROC images, we identified localized regions where the lunar surface remains illuminated for nearly 94% of the year with the longest eclipsed period lasting only 43 h. We also identified small illuminated peaks (tens of meters across) in areas previously modeled to be in shadow. Together, the WAC and NAC dataset provide direct, high resolution observations of the actual surface illumination environment of potential exploration sites near the lunar poles.