A New Geological Map of the Apollo 15 Landing Site and Its Implications

The Apollo mission data and samples have led to substantial advancements in our understanding of the Moon's geological history and processes. By incorporating new data from recent orbital missions, we systematically developed high-resolution geological maps for each Apollo landing site [e.g., 1-3]. The present study offers a detailed geological map for the Apollo 15 site. The Apollo 15 mission is noteworthy for its significant contributions to lunar geology, leading to substantial advancements in our understanding of volcanic activity, impact cratering, and the Moon's thermal evolution. Notwithstanding this progress, there are as yet unanswered scientific questions, which have been articulated as objectives for future missions such as the 500-day Hadley Max design reference mission (DRM) [4,5].

The Apollo 15 landing site is located east of Hadley Rille on mare basalts that border the Imbrium basin. A thorough geological mapping of the area has revealed the presence of multiple units associated with the Imbrium basin, including its rim and ejecta deposits. These units have been classified based on their distinguishing topographic features. The surrounding area also contains plains deposits, such as Imbrian light plains, along with several mare basalt units of Eratosthenian and Imbrian age [6]. Materials from nearby craters, Autolycus and Aristillus [7,8], also contribute to the region's geological diversity. The linear rilles in proximity to the site have been mapped and categorized by age, employing a combination of stratigraphic relationships and morphological analysis.

The newly developed maps have enhanced the measurement of crater-size frequency distributions (CSFDs), leading to improved N(1) values and a refined lunar cratering chronology [1-3]. Furthermore, the maps facilitate the identification of potential sample sources, thereby enhancing our comprehension of lunar stratigraphy [4,5]. Finally, these maps provide a fundamental framework for the evaluation of in-situ resources and the testing of novel technologies for forthcoming lunar missions [9].

[1] Iqbal et al. (2019) Icarus 333, 528-547.

[2] Iqbal et al. (2020) Icarus 352, 113991.

[3] Iqbal et al. (2023) Icarus 407, 115732.

[4] Daniti et al. (2024) LPSC 55, #1667.

[5] Iqbal et al. (2024) LPSC 55, #1010.

[6] Hiesinger et al. (2000) JGR 105, 29239-29275.

[7] Hiesinger et al. (2000) JGR 105, 29239-29275.

[8] Carr et al. (1971) USGS, I-723.

[9] van der Bogert, et al. (2020) LPSC 51, #1876.