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The lunar cratering chronology is fundamentally important, because it is not just used to determine ages for unsampled lunar surfaces, but is commonly applied to other planetary bodies. As part of a systematic study of the calibration of the lunar cratering chronology at the Apollo landing sites, we produced a new detailed geological map of the Apollo 12 landing site, using recent orbital data including Lunar Reconnaissance orbiter (LRO) Narrow Angle (NAC) and Wide Angle (WAC) images, and a Lunar Orbiter Laser Altimeter (LOLA)/SELENE merged digital elevation model (DEM), as well as Chandrayaan M3 spectral data. Using high-resolution LRO NAC images and NAC-derived DTMs, new crater size-frequency distributions (CSFDs) were measured on the updated geological units to determine crater retention ages or N(1) values (i.e., the cumulative number of craters with diameters ≥1 km). Since the Apollo 12 landing site is located in Oceanus Procellarum on a ray of Copernicus crater, it provides two possible calibration points for the lunar cratering chronology: (1) a mare basalt surface age, and (2) an approximate age for Copernicus crater via its ray material. We calibrated our new N(1) values with recently determined radiometric ages of Apollo 12 basalt samples, and compare our results with work done by Hiesinger et al. (2012) for Copernicus crater, and the Neukum (1983) chronology. The updated calibration points are consistent with the lunar chronology of Neukum (1983), which indicates that no updates to this function are currently necessary.

In this paper, we investigate how well an automatic crater detection algorithm is suitable to determine the surface age of different lunar regions. A template-based crater detection algorithm is used to analyze image data under known illumination conditions. For this purpose, artificially illuminated crater templates are used to detect and count craters and their diameters in the areas under investigation. The automatic detection results are used to obtain the crater size-frequency distribution (CSFD) for the examined areas, which is then used for estimating the absolute model age (AMA) of the surface. The main focus of this work is to find out whether there exists an ideal sensitivity value for automatic crater detection to obtain smallest possible errors between the automatically derived AMA and a reference AMA derived from manually detected craters. The detection sensitivity threshold of our crater detection algorithm (CDA) is calibrated based on five different regions in Mare Cognitum on the Moon such that the age inferred from the manual crater counts corresponds to the age inferred from the CDA results. The obtained best detection threshold value is used to apply the CDA algorithm to another five regions in the lunar Oceanus Procellarum region. The accuracy of the method is examined by comparing the calculated AMAs with the manually determined ones from the literature. It is shown that the automatic age estimation yields AMA values that are generally consistent with the reference values with respect to the one standard deviation errors.

Data for:China’s Chang’e-5 landing site: Geology, stratigraphy, and provenance of materials Data List: [1] "CE5_Geologic Map_4244N5053W_Qian2021.7z" for Figure 5 (Geological map of the CE-5 landing site) [2] "CE5_Crater Counts_Landing Site.7z" for Figure 6 (CSFD measurements of the CE-5 landing site) [3] "CE5_Distal Ejecta Distribution.7z" for Figure 7 (Ejecta distribution of major source craters in the Northern Oceanus Procellarum) Reference Qian, Y., Xiao, L., Wang, Q., Head, J.W., Yang, R., Kang, Y., van der Bogert, C.H., Hiesinger, H., Lai, X., Wang, G., Pang, Y., Zhang, N., Yuan, Y., He, Q., Huang, J., Zhao, J., Wang, J., Zhao, S., 2021. China’s Chang’e-5 landing site: Geology, stratigraphy, and provenance of materials. Earth Planet. Sci. Lett. 561, 116855. https://doi.org/10.1016/j.epsl.2021.116855 Contact Yuqi Qian (yuqi_qian@cug.edu.cn, yuqii.qian@gmail.com), School of Earth Sciences, China University of Geosciences, Wuhan, China

Data for:China’s Chang’e-5 landing site: Geology, stratigraphy, and provenance of materials Data List: [1] "CE5_Geologic Map_4244N5053W_Qian2021.7z" for Figure 5 (Geological map of the CE-5 landing site) [2] "CE5_Distal Ejecta Distribution.7z" for Figure 7 (Ejecta distribution of major source craters in the Northern Oceanus Procellarum) Reference Qian, Y., Xiao, L., Wang, Q., Head, J.W., Yang, R., Kang, Y., van der Bogert, C.H., Hiesinger, H., Lai, X., Wang, G., Pang, Y., Zhang, N., Yuan, Y., He, Q., Huang, J., Zhao, J., Wang, J., Zhao, S., 2021. China’s Chang’e-5 landing site: Geology, stratigraphy, and provenance of materials. Earth Planet. Sci. Lett. 561, 116855. https://doi.org/10.1016/j.epsl.2021.116855 Contact Yuqi Qian (yuqii.qian@gmail.com), School of Earth Sciences, China University of Geosciences, Wuhan, China