Lunar secondary crater distributions and ejecta fragment size velocity distributions: implications for regolith redistribution
- 1Southwest Research Institute, Boulder, USA (ksinger@boulder.swri.edu)
- 2University of Colorado, Boulder, USA
- 3Lunar and Planetary Institute, League City, USA
- 4United States Geologic Survey, Flagstaff, USA
- 5Washington University in St. Louis, St. Louis, USA
We have performed an extensive study of secondary craters associated with specific primary craters on the Moon. These data can be used to understand aspects of both (1) the secondary craters themselves and (2) the ejecta fragments that formed them. Studying ejecta and secondary craters are a part of understanding the overall contributions of impacts to shaping and redistributing material across the lunar surface.
We produced secondary crater size-range distributions for a large range of primary crater sizes (~0.8-660 km dimeter primaries). Our results can be used to make a map of estimated maximum secondary crater sizes across the Moon. They can also be used to test if a specific secondary crater cluster is likely related to a given primary crater.
We also produced ejecta fragment size-velocity distributions for all our study sites. These results can be used to understand the size and velocity of the ejecta fragments that were ejected as part of the primary impact. This helps us understand the dynamics of the primary impact and the formation of fragments (or clusters of fragments) and how they are ejected during the passage of the shock wave through a planetary surface. This new empirical data can be used to help constrain analytical and numerical models of dynamic fragmentation, place constraints on the largest ejecta fragments expected be ejected at escape velocity from the Moon, and used as inputs into models of regolith development and impact gardening.
We will present the most current results on the above topics. Initial results for 6 primary craters are presented in Singer et al. 2020 where we discovered a previously unrecognized trend where the size velocity distributions are dependent on the size of the impact (i.e., scale dependent). We now have data on 10 additional primaries and further applications of the study.
Singer, K. N., Jolliff, B. L., & McKinnon, W. B. (2020). Lunar secondary craters and estimated ejecta block sizes reveal a scale-dependent fragmentation trend. J. Geophys. Res., 125(8), e2019JE006313. doi:10.1029/2019JE006313
How to cite: Singer, K., Skjetne, H., Stopar, J., Huffman, M., Chapman, C., Ostrach, L., Jolliff, B., and McKinnon, W.: Lunar secondary crater distributions and ejecta fragment size velocity distributions: implications for regolith redistribution, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-3992, https://doi.org/10.5194/egusphere-egu23-3992, 2023.
