Landing site choice for Luna-27 mission in the Moon South Polar Region

In this study, we examine the Russian automatic lunar missions "Luna-25," "Luna-26," and the scientific objectives and landing site of the "Luna-27 '' spacecraft. The landing of "Luna-27 '' is planned directly in the South Polar region, which, due to ballistic and engineering requirements, is confined to a sector extending from 51 degrees E to 1 degrees W in longitude and from 83 degrees S to 79 degrees S in latitude. This area is characterized by complex terrain, and to identify suitable landing territories, a suitability map has been created that takes into account the distribution of slopes, the degree of illumination, and visibility of Earth. A total of five sites measuring 30 x 15 km (landing ellipse) within the considered region meet such scientific and technical requirements as slope distributions of less than 7-10 degrees, sunlight illumination of more than 35 %, and Earth visibility of more than 50 %. All landing sites are ranked by priority from 1 to 5 depending on the content of water equivalent of hydrogen (WEH) in the lunar soil. Site N degrees 1, by its characteristics, is considered the best and may be chosen as the primary landing site, while sites N degrees 2 and N degrees 3 could serve as backups. It is demonstrated that with increased landing precision, with a deviation probability from the given point up to 0.5 km, the number of suitable landing sites satisfying primarily scientific rather than engineering-technical safety criteria, which are also inherently met, significantly increases.