Project P7: Impact experiments at high speeds and fragment distributions

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Remote infrared observations reveal that debris disks exhibit an enhanced thermal emission due to micrometer sized dust particles. The structural state and the thermal emission of dust matter are determined by collisions between the particles and stellar wind irradiation (so-called space weathering). The ultimate goal of this project is to simulate the effects of particle collisions and space weathering in laser experiments and to characterize the structural damage by high-resolution electron microscopy and spectroscopy. Based on these data we expect to improve debris disk models and better understand observational data of debris disks. Our preliminary work demonstrates impressively the feasibility of the experimental approach. In first laser experiments on olivine we observed the formation of typical shock effects (planar fractures and c dislocations) and space weathering phenomena (amorphization and nano-Fe). This interdisciplinary project is devoted to optimize and calibrate the experimental setups such that systematic experiments can be carried out at variable pressure-temperature conditions. The experiments will be performed on planetologically relevant minerals (olivine, pyroxene, troilite, FeNi phases). The use of transmission electron microscopy is mandatory to detect and characterize the defects in laser-irradiated minerals. This project is complementary to P6, using different techniques, materials, and parameter ranges, and will provide input for models of P1, P2, and P3.