The Crater Chains of Vesta - a Morphological Study

Abstract

Abstract The Dawn spacecraft spent 141 days in the Low Mapping Orbit (LAMO) around Vesta obtaining 10251 images with an average resolution of 20m per pixel. The surface of Vesta displays a diverse geological structure - numerous impact craters, extensive ejecta blankets, giant troughs around the equator, impact basins, and regions with enigmatic dark as well as bright material (1). The LAMO imaging data set has been used to search, over the entire illuminated surface, for crater chains, which are groups of depressions (round or elongated) in mostly linear alignments - resembling a chain of pearls. More than 300 features were identified as crater chains most of which have an East - West orientation. Based on morphology the observed crater chains were divided into 5 subgroups. 1) Single crater chain (A) - a linear alignment of craters associated with other types of linear features (e.g. grooves, faults, troughs, ridges, or trenches). 2) Single crater chain (NA) - a linear alignment of craters not associated with other types of linear features. 3) Crater chain families - segments of short crater chains aligned parallel to each other. Some are associated with lineaments and some are not. 4) Swarm - a wide “band” of craters stretching in the East - West direction. 5) Special cases which do not fit in the other groups or are mixtures of the other types. The global distribution of crater chains and crater counts will be used to analyze the various morphological groups. Hypotheses for the formation mechanisms of the different groups will be explored. (1) Jaumann, et al, 2012 - Science 336,687-690