Department of Earth Sciences

Subproject A3 “Ancient bombardment of the inner solar system – Reinvestigation of the ‘fingerprints’ of different impactor populations” 

In the Collaborative Research Centre „Late Accretion onto Terrestrial Planets“, scientists from five institutions (Freie Universität Berlin, Technische Universität Berlin, University of Münster, German Aerospace Center, Museum für Naturkunde) investigated the late accretion history of planetary bodies in the inner solar system from 4.5 to 3.8 billion years ago. The Planetary Sciences and Remote Sensing research group at Freie Universität Berlin was involved in one of the 16 subprojects. This subproject A3 “Ancient bombardment of the inner solar system – Reinvestigation of the ‘fingerprints’ of different impactor populations“, is focused on the lunar cratering record and analyses based on crater size-frequency distributions (CSFDs). Although CSFDs are widely used for relative and absolute age determinations of lunar surfaces, it is still not clear if there was more than one impactor population involved in the formation of the Moon’s cratering record during the late accretion period. Since current methodologies for dating lunar surfaces assume there was only one population, i.e., the origin of impacting projectiles remained constant, a combination of different populations would influence the age determination results significantly. In subproject A3, we thus conducted detailed geological mapping and crater size-frequency measurements in combination with new approaches of GIS spatial analyses to investigate the shapes of CSFDs and to validate the suitability of regions which were previously used for this purpose. Altogether, this helped to improve the methods of CSFD-based age determination, to examine a potential time-variable lunar crater production function and to further understand the late accretion history of planetary bodies in the inner solar system.