title: COMETARY SCIENCE. The landing(s) of Philae and inferences about comet surface mechanical properties.
abstract: The Philae lander, part of the Rosetta mission to investigate comet 67P/Churyumov-Gerasimenko, was delivered to the cometary surface in November 2014. Here we report the precise circumstances of the multiple landings of Philae, including the bouncing trajectory and rebound parameters, based on engineering data in conjunction with operational instrument data. These data also provide information on the mechanical properties (strength and layering) of the comet surface. The first touchdown site, Agilkia, appears to have a granular soft surface (with a compressive strength of 1 kilopascal) at least ~20 cm thick, possibly on top of a more rigid layer. The final landing site, Abydos, has a hard surface.
authors.affiliation: Deutsches Zentrum für Luft- und Raumfahrt (DLR)/Raumflugbetrieb und Astronautentraining, Microgravity User Support Center (MUSC), Linder Höhe 1, 51147 Cologne, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Biele
authors.affiliation: Deutsches Zentrum für Luft- und Raumfahrt (DLR)/Raumflugbetrieb und Astronautentraining, Microgravity User Support Center (MUSC), Linder Höhe 1, 51147 Cologne, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Ulamec
authors.affiliation: Deutsches Zentrum für Luft- und Raumfahrt (DLR)/Raumflugbetrieb und Astronautentraining, Microgravity User Support Center (MUSC), Linder Höhe 1, 51147 Cologne, Germany.
authors.forename: Michael
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authors.lastname: Maibaum
authors.affiliation: Max-Planck-Institut für Sonnensystemforschung (MPS), Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Roll
authors.affiliation: DLR/Institut für Raumfahrtsysteme, Robert Hooke-Straße 7, 28359 Bremen, Germany.
authors.forename: Lars
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authors.lastname: Witte
authors.affiliation: Centre National d'Études Spatiales, 18 Avenue Édouard Belin, 31400 Toulouse, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Jurado
authors.affiliation: European Space Agency/European Space Operations Centre (ESA/ESOC), Robert-Bosch-Straße 5, 64293 Darmstadt, Germany. Grupo Mecánica de Vuelo at ESA/ESOC - GMV Robert-Bosch-Straße 5, 64293 Darmstadt, Germany.
authors.forename: Pablo
authors.initials: P
authors.lastname: Muñoz
authors.affiliation: 1. Physikalisches Institut, Georg August Universität, 37077 Göttingen, Germany; permanent address: Department of Materials Science, Saarland University, 66123 Saarbrücken, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Arnold
authors.affiliation: Institut für Geophysik und Extraterrestrische Physik, Technische Universität Braunschweig Mendelssohnstrasse 3, 38106 Braunschweig, Germany.
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Auster
authors.affiliation: European Space Agency/European Space Operations Centre (ESA/ESOC), Robert-Bosch-Straße 5, 64293 Darmstadt, Germany. Grupo Mecánica de Vuelo at ESA/ESOC - GMV Robert-Bosch-Straße 5, 64293 Darmstadt, Germany.
authors.forename: Carlos
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authors.lastname: Casas
authors.affiliation: DLR/Institut für Planetenforschung Rutherfordstraße 2, 12489 Berlin, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Faber
authors.affiliation: Deutsches Zentrum für Luft- und Raumfahrt (DLR)/Raumflugbetrieb und Astronautentraining, Microgravity User Support Center (MUSC), Linder Höhe 1, 51147 Cologne, Germany.
authors.forename: Cinzia
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authors.affiliation: Deutsches Zentrum für Luft- und Raumfahrt (DLR)/Raumflugbetrieb und Astronautentraining, Microgravity User Support Center (MUSC), Linder Höhe 1, 51147 Cologne, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Finke
authors.affiliation: Deutsches Zentrum für Luft- und Raumfahrt (DLR)/Raumflugbetrieb und Astronautentraining, Microgravity User Support Center (MUSC), Linder Höhe 1, 51147 Cologne, Germany.
authors.forename: Hans-Herbert
authors.initials: HH
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authors.affiliation: Deutsches Zentrum für Luft- und Raumfahrt (DLR)/Raumflugbetrieb und Astronautentraining, Microgravity User Support Center (MUSC), Linder Höhe 1, 51147 Cologne, Germany.
authors.forename: Koen
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authors.lastname: Geurts
authors.affiliation: Max-Planck-Institut für Sonnensystemforschung (MPS), Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Güttler
authors.affiliation: Institut für Geophysik und Extraterrestrische Physik, Technische Universität Braunschweig Mendelssohnstrasse 3, 38106 Braunschweig, Germany.
authors.forename: Philip
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authors.lastname: Heinisch
authors.affiliation: Université Grenoble Alpes and CNRS, Institut de Planétologie et d'Astrophysique de Grenoble, F-38000 Grenoble, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Herique
authors.affiliation: DLR/Institut für Planetenforschung Rutherfordstraße 2, 12489 Berlin, Germany.
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authors.affiliation: Institut für Weltraumforschung (IWF) Graz, Austria Austrian Academy of Sciences, Space Research Institute, Schmiedlstraße 6, 8042 Graz, Austria.
authors.forename: Günter
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authors.affiliation: DLR/Institut für Planetenforschung Rutherfordstraße 2, 12489 Berlin, Germany.
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authors.affiliation: DLR/Institut für Planetenforschung Rutherfordstraße 2, 12489 Berlin, Germany.
authors.forename: Jörg
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authors.lastname: Knollenberg
authors.affiliation: Université Grenoble Alpes and CNRS, Institut de Planétologie et d'Astrophysique de Grenoble, F-38000 Grenoble, France.
authors.forename: Wlodek
authors.initials: W
authors.lastname: Kofman
authors.affiliation: Institut für Weltraumforschung (IWF) Graz, Austria Austrian Academy of Sciences, Space Research Institute, Schmiedlstraße 6, 8042 Graz, Austria.
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authors.initials: N
authors.lastname: Kömle
authors.affiliation: DLR/Institut für Planetenforschung Rutherfordstraße 2, 12489 Berlin, Germany.
authors.forename: Ekkehard
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authors.affiliation: Deutsches Zentrum für Luft- und Raumfahrt (DLR)/Raumflugbetrieb und Astronautentraining, Microgravity User Support Center (MUSC), Linder Höhe 1, 51147 Cologne, Germany.
authors.forename: Valentina
authors.initials: V
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authors.affiliation: DLR/Institut für Planetenforschung Rutherfordstraße 2, 12489 Berlin, Germany.
authors.forename: Stefano
authors.initials: S
authors.lastname: Mottola
authors.affiliation: European Space Agency/European Space Operations Centre (ESA/ESOC), Robert-Bosch-Straße 5, 64293 Darmstadt, Germany. Grupo Mecánica de Vuelo at ESA/ESOC - GMV Robert-Bosch-Straße 5, 64293 Darmstadt, Germany.
authors.forename: Ramon
authors.initials: R
authors.lastname: Pardo de Santayana
authors.affiliation: Centre National d'Études Spatiales, 18 Avenue Édouard Belin, 31400 Toulouse, France.
authors.forename: Emile
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authors.affiliation: DLR/Institut für Planetenforschung Rutherfordstraße 2, 12489 Berlin, Germany.
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authors.affiliation: DLR/Institut für Planetenforschung Rutherfordstraße 2, 12489 Berlin, Germany.
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authors.initials: KJ
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authors.affiliation: Max-Planck-Institut für Sonnensystemforschung (MPS), Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany.
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authors.affiliation: DLR/Institut für Planetenforschung Rutherfordstraße 2, 12489 Berlin, Germany.
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