Exploring New Worlds: Dawn at Vesta

Kurzfassung

Abstract Dawn has completed its exploration of Vesta after spending more than a year mapping the surface and sensing the interior. Vesta is shown to be an object whose evolution is similar to the terrestrial planets, including full igneous differentiation, geologic layering, global tectonic features, and significant mass wasting. Vesta experienced a violent impact history, surviving near fatal collisions that left global scars. Its impact history provides critical constraints on dynamical models of early solar system formation due to its position near the center of the main asteroid belt. While Vesta is very bright on average, dark material is observed with uneven distribution across the body and appears to mix with, and darken, the original Vestan crust, resulting in a large range of albedo. Diversity in mineralogy exists at all scales, from hemispheric dichotomies to small-scale variations exposed by impact gardening. Elemental abundances have been mapped and reveal regional differences in bulk-regolith composition. Vesta’s composition and impact history confirm it to be the parent body of the HED meteorites. Vesta has a substantial iron core, and significant high-degree gravity anomalies that may reflect variations in crustal density and/or thickness. The nature of Vesta’s magmatic evolution, the strength and mechanical properties of its crust, and the sources of the enigmatic compositional layering are some of the topics being explored in depth with Dawn data. The spacecraft is now enroute to the dwarf planet Ceres, where it arrives in February 2015.