Analytical scanning and transmission electron microscopy of laboratory impacts on Stardust aluminum foils: Interpreting impact crater morphology and the composition of impact residues

Authors

  • Anton T. Kearsley,

    Corresponding author
    1. Department of Mineralogy, Impact and Astromaterials Research Centre, Natural History Museum, Cromwell Road, South Kensington, London SW7 5BD, UK
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  • Giles A. Graham,

    1. Department of Mineralogy, Impact and Astromaterials Research Centre, Natural History Museum, Cromwell Road, South Kensington, London SW7 5BD, UK
    2. Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, Livermore, California 94551, USA
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  • Mark J. Burchell,

    1. School of Physical Sciences, University of Kent, Canterbury, CT2 7NH, UK
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  • Michael J. Cole,

    1. School of Physical Sciences, University of Kent, Canterbury, CT2 7NH, UK
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  • Zu Rong Dai,

    1. Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, Livermore, California 94551, USA
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  • Nicholas Teslich,

    1. Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, Livermore, California 94551, USA
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  • John P. Bradley,

    1. Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, Livermore, California 94551, USA
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  • Richard Chater,

    1. Imperial College of Science, Technology and Medicine, Exhibition Road, South Kensington, London SW7 2BP
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  • Penelope A. Wozniakiewicz,

    1. Department of Mineralogy, Impact and Astromaterials Research Centre, Natural History Museum, Cromwell Road, South Kensington, London SW7 5BD, UK
    2. Imperial College of Science, Technology and Medicine, Exhibition Road, South Kensington, London SW7 2BP
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  • John Spratt,

    1. Department of Mineralogy, Impact and Astromaterials Research Centre, Natural History Museum, Cromwell Road, South Kensington, London SW7 5BD, UK
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  • Gary Jones

    1. Department of Mineralogy, Impact and Astromaterials Research Centre, Natural History Museum, Cromwell Road, South Kensington, London SW7 5BD, UK
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*antk@nhm.ac.uk

Abstract

Abstract— The known encounter velocity (6.1 kms−1) and particle incidence angle (perpendicular) between the Stardust spacecraft and the dust emanating from the nucleus of comet Wild-2 fall within a range that allows simulation in laboratory light-gas gun (LGG) experiments designed to validate analytical methods for the interpretation of dust impacts on the aluminum foil components of the Stardust collector. Buckshot of a wide size, shape, and density range of mineral, glass, polymer, and metal grains, have been fired to impact perpendicularly on samples of Stardust Al 1100 foil, tightly wrapped onto aluminum alloy plate as an analogue of foil on the spacecraft collector. We have not yet been able to produce laboratory impacts by projectiles with weak and porous aggregate structure, as may occur in some cometary dust grains. In this report we present information on crater gross morphology and its dependence on particle size and density, the pre-existing major- and trace-element composition of the foil, geometrical issues for energy dispersive X-ray analysis of the impact residues in scanning electron microscopes, and the modification of dust chemical composition during creation of impact craters as revealed by analytical transmission electron microscopy. Together, these observations help to underpin the interpretation of size, density, and composition for particles impacted on the Stardust aluminum foils.

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