The KREEP-rich circum-Lalande region: A candidate landing area for future lunar crewed missions

The lunar magma ocean hypothesis suggests that the primordial KREEP (an acronym of potassium (K), rare earth element (REE), and phosphorus (P)) was the final product of fractional crystallization. However, the primordial KREEP (a.k.a. urKREEP) has never been identified in previous lunar samples or meteorites. The Moon is the focus of many countries’ and agencies’ space exploration plans, and with the advancement of technology, crewed missions have been proposed. We propose two candidate landing sites, located respectively in the northwest (9.5°W, 0.9°S) and southeast (11.1°W, 6.2°S) of Lalande crater (8.6°W, 4.5°S), for future crewed missions, with the primary goal of sampling the speculated urKREEP. Both sites are situated on the Th- (a critical marker of KREEP) and silica-rich Lalande ejecta in the Mare Insularum and Mare Nubium, respectively. Their geolocations at the low latitude on the lunar nearside, the flat surface, and the low rock abundance suggest the sites are safe for landing and meet the needs of real-time Earth–Moon communication. The astronauts could perform many extravehicular activities, such as collecting KREEP-rich samples, screening clast samples, and drilling regolith cores, to gather a variety of samples, such as Lalande ejecta, basalts, Copernicus ejecta, and regolith. The returned samples are valuable to explore the speculated urKREEP, to reveal the relationship between heat-producing elements and volcanism, to refine the lunar cratering chronology function, and to investigate volatiles in the regolith.