Simulation of Space Weathering on airless bodies, moons and planets: Combining hypervelocity dust impacts with energetic irradiation

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The chemical and mineralogical characterization of meteorites and their parent asteroids provides us with important information about the processes and conditions during the formation era of the inner Solar System. However, linking meteorites to their parent bodies, e.g., by infrared reflectance spectra, is still problematic. The surfaces of atmosphereless celestial bodies are continuously bombarded by solar wind, meteoroids, cosmic dust and cosmic rays. These processes, summarized under the term Space Weathering cause strong alterations of the surfaces of these bodies. Astronomical observations aim to reconstruct the surface properties of the surfaces of asteroids, moons and planets by infrared spectra, but space weathering severely modifies the optical, compositional and physical properties of thin surface layers and thus precludes proper identification of its chemistry and mineralogy. The effects of space weathering have been experimentally studied, mainly with respect to ion bombardment and sputtering and here, with emphasis on the formation of glassy coatings and nano phase iron. Other studies aimed to simulate the influence of micrometeoroid bombardment by using nanosecond-pulsed laser shots, which - however - cannot be directly compared to real micrometeoroid impacts. This study offers a new approach to simulate cosmic dust bombardment by using a modified 2 MV van de Graaff dust accelerator at the Max-Planck-Institute for Nuclear Physics, operated by the Institute for Space Systems (IRS) at the University of Stuttgart, and combine these with energetic irradiation and desorption experiments at the Electron and Photon Induced Chemistry on Surfaces (EPICS) laboratory at the Georgia Institute of Technology, USA. By simulating highly realistic irradiation and bombardment conditions, this allows to investigate the processes of both, cosmic dust bombardment and solar wind irradiation on solid planetary surfaces and to study the formation of nano phase iron, the role of hydrous minerals and the effect on volatile budgets, using a variety of silicate materials. I expect this work to contribute to a better understanding of alteration mechanisms in space environments, nanophase iron formation and the development of volatiles on desiccated surfaces.