title: COMETARY SCIENCE. Thermal and mechanical properties of the near-surface layers of comet 67P/Churyumov-Gerasimenko.
abstract: Thermal and mechanical material properties determine comet evolution and even solar system formation because comets are considered remnant volatile-rich planetesimals. Using data from the Multipurpose Sensors for Surface and Sub-Surface Science (MUPUS) instrument package gathered at the Philae landing site Abydos on comet 67P/Churyumov-Gerasimenko, we found the diurnal temperature to vary between 90 and 130 K. The surface emissivity was 0.97, and the local thermal inertia was 85 ± 35 J m(-2) K(-1)s(-1/2). The MUPUS thermal probe did not fully penetrate the near-surface layers, suggesting a local resistance of the ground to penetration of >4 megapascals, equivalent to >2 megapascal uniaxial compressive strength. A sintered near-surface microporous dust-ice layer with a porosity of 30 to 65% is consistent with the data.
authors.affiliation: Institute of Planetary Research, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Berlin, Germany. tilman.spohn@dlr.de.
authors.forename: T
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authors.lastname: Spohn
authors.affiliation: Institute of Planetary Research, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Berlin, Germany.
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authors.affiliation: European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), Noordwijk, Netherlands.
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authors.affiliation: Space Research Center, Warsaw, Poland.
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authors.affiliation: Institute of Planetary Research, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Berlin, Germany.
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authors.affiliation: Institute of Planetary Research, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Berlin, Germany.
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authors.lastname: Hüttig
authors.affiliation: Department of Physical Sciences, The Open University, Milton Keynes, UK.
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authors.affiliation: Space Research Institute, Austrian Academy of Sciences Graz, Austria.
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authors.lastname: Kargl
authors.affiliation: Department of Physical Sciences, The Open University, Milton Keynes, UK.
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authors.lastname: Kaufmann
authors.affiliation: Space Research Institute, Austrian Academy of Sciences Graz, Austria.
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authors.lastname: Kömle
authors.affiliation: Institute of Planetary Research, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Berlin, Germany.
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authors.lastname: Kührt
authors.affiliation: Faculty of Physics, University of Warsaw, Warsaw, Poland.
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authors.affiliation: Space Research Center, Warsaw, Poland.
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authors.affiliation: Institute of Planetary Research, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Berlin, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Pelivan
authors.affiliation: Institute of Planetary Research, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Berlin, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Schrödter
authors.affiliation: Physics Institute, University of Berne, Berne, Switzerland.
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authors.lastname: Seiferlin