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1. Radar investigations of Apollinaris Mons on Mars: Exploring the origin of the fan deposits.

Author

El-Maarry, M.R., Heggy, E., and Dohm, J.M.

Subjects
*SHIELD volcanoes, *RADAR, *CRATERING, *SEDIMENTATION & deposition, *FLUVIAL geomorphology, *MARS (Planet)
Abstract

Apollinaris Mons is an isolated volcano on Mars straddling the boundary between the southern highlands and the northern plains. One of its most distinctive features is its massive fan-shaped deposit that extends from a breach on its summit to distances of more than 150 km and drapes its entire southern flank. The composition and formation mechanism of these deposits remains controversial. We investigate the radar properties of the fan deposits (FD) of Apollinaris Mons using low-frequency sounding radar data in combination with high-resolution images and crater-size frequency analysis to constrain their inner shape and bulk composition. Our analysis indicates that the FD attains an irregular thickness and is gradually thinner towards their lateral margins. The crater-size frequency analysis shows that they may have undergone repeated resurfacing, which is suggestive of long-term evolution. Our analysis of Shallow Radar (SHARAD) radargrams traversing different sections of the FD reveals multiple and different subsurface interfaces among the radargrams crossing the thinnest part, which suggests a layered and complex inner shape. Our estimates for the bulk real part of the dielectric constant of the FD ranges from 3 to 5, which is consistent with an icy-silicate mixture or pyroclastic composition. Therefore, we conclude that lahars or pyroclastic flows are the most likely mechanism that created the FD, yet we cannot rule out additional contributions from lava flows. A combination of multiple processes is also possible since the deposits appear to have been modified by fluvial processes at a later stage of their formation. [ABSTRACT FROM AUTHOR]

Published
2014
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2. The WISDOM Radar: Unveiling the Subsurface Beneath the ExoMars Rover and Identifying the Best Locations for Drilling

Author

Valérie Ciarletti, Stephen Clifford, Dirk Plettemeier, Alice Le Gall, Yann Hervé, Sophie Dorizon, Cathy Quantin-Nataf, Wolf-Stefan Benedix, Susanne Schwenzer, Elena Pettinelli, Essam Heggy, Alain Herique, Jean-Jacques Berthelier, Wlodek Kofman, Jorge L. Vago, Svein-Erik Hamran, null the WISDOM Team, PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Lunar and Planetary Institute [Houston] (LPI), Technische Universität Dresden = Dresden University of Technology (TU Dresden), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut für Nachrichtentechnik [Dresden] (IfN), Centre for Earth, Planetary, Space and Astronomical Research [Milton Keynes] (CEPSAR), The Open University [Milton Keynes] (OU), Dipartimento di Matematica e Fisica [Roma], Università degli Studi Roma Tre, Ming Hsieh Department of Electrical Engineering [Los Angeles], USC Viterbi School of Engineering, University of Southern California (USC)-University of Southern California (USC), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), Forsvarets Forskningsinstitutt (FFI), IMPEC - LATMOS, Technische Universität Dresden (TUD), Dipartimento di Matematica e Fisica [Rome], Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Polska Akademia Nauk (PAN), Ciarletti, V., Clifford, S., Plettemeier, D., Le Gall, A., Herve, Y., Dorizon, S., Quantin-Nataf, C., Benedix, W. -S., Schwenzer, S., Pettinelli, E., Heggy, E., Herique, A., Berthelier, J. -J., Kofman, W., Vago, J. L., Hamran, S. -E., Ciarletti, Valérie, Clifford, Stephen, Plettemeier, Dirk, Le Gall, Alice, Hervé, Yann, Dorizon, Sophie, Quantin-Nataf, Cathy, Benedix, Wolf-Stefan, Schwenzer, Susanne, Pettinelli, Elena, Heggy, Essam, Herique, Alain, Berthelier, Jean-Jacque, Kofman, Wlodek, Vago, Jorge L., Hamran, Svein-Erik, Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi Roma Tre = Roma Tre University (ROMA TRE), and Agence Spatiale Européenne = European Space Agency (ESA)

Subjects
010504 meteorology & atmospheric sciences, Special Collection of Papers: ExoMars Rover MissionGuest Editor: Jorge L. Vago, Life on Mars, 01 natural sciences, Astrobiology, law.invention, Ground penetrating radar, law, 0103 physical sciences, Radar, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Drill, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Drilling, Martian shallow subsurface, Mars Exploration Program, Regolith, Agricultural and Biological Sciences (miscellaneous), ExoMars, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Stratigraphy, 13. Climate action, Space and Planetary Science, Ground-penetrating radar, Geology
Abstract

International audience; The search for evidence of past or present life on Mars is the principal objective of the 2020 ESA-Roscosmos ExoMars Rover mission. If such evidence is to be found anywhere, it will most likely be in the subsurface, where organic molecules are shielded from the destructive effects of ionizing radiation and atmospheric oxidants. For this reason, the ExoMars Rover mission has been optimized to investigate the subsurface to identify, understand, and sample those locations where conditions for the preservation of evidence of past life are most likely to be found. The Water Ice Subsurface Deposit Observation on Mars (WISDOM) ground-penetrating radar has been designed to provide information about the nature of the shallow subsurface over depth ranging from 3 to 10 m (with a vertical resolution of up to 3 cm), depending on the dielectric properties of the regolith. This depth range is critical to understanding the geologic evolution stratigraphy and distribution and state of subsurface H2O, which provide important clues in the search for life and the identification of optimal drilling sites for investigation and sampling by the Rover's 2-m drill. WISDOM will help ensure the safety and success of drilling operations by identification of potential hazards that might interfere with retrieval of subsurface samples. Key Words: Ground penetrating radar—Martian shallow subsurface—ExoMars. Astrobiology 17, 565–584.

Published
2017
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3. Mars North Polar Deposits: Stratigraphy, Age, and Geodynamical Response

Author

Nathaniel E. Putzig, P. Surdas Mohit, Essam Heggy, James W. Head, M. Cutigni, S. M. Milkovich, John W. Holt, Lucia Marinangeli, Elena Pettinelli, Suzanne E. Smrekar, Maria T. Zuber, Michael T. Mellon, Lynn M. Carter, Ali Safaeinili, Roberto Seu, F. Russo, Richard W. Zurek, Roberto Orosei, Daniela Biccari, Carl Leuschen, Roger J. Phillips, Bruce A. Campbell, Kenneth L. Tanaka, E. Giacomoni, Anthony F. Egan, Giovanni Picardi, Jeffrey J. Plaut, PHILLIPS R., J, ZUBER M., T, SMREKAR S., E, MELLON M., T, HEAD J., W, TANAKA K., L, PUTZIG N., E, MILKOVICH S., M, CAMPBELL B., A, PLAUT J., J, Safaeinili, A, Seu, R, Biccari, D, CARTER L., M, Picardi, G, Orosei, R, MOHIT P., S, Heggy, E, ZUREK R., W, EGAN A., F, Giacomoni, E, Russo, F, Cutigni, M, Pettinelli, Elena, HOLT J., W, LEUSCHEN C., J, and Marinangeli, L.

Subjects
Orbiter, Multidisciplinary, law, Lithosphere, Polar, Orbital eccentricity, Geophysics, Mars Exploration Program, Radar, Geodynamics, Geology, Mantle (geology), law.invention
Abstract

The Shallow Radar (SHARAD) on the Mars Reconnaissance Orbiter has imaged the internal stratigraphy of the north polar layered deposits of Mars. Radar reflections within the deposits reveal a laterally continuous deposition of layers, which typically consist of four packets of finely spaced reflectors separated by homogeneous interpacket regions of nearly pure ice. The packet/interpacket structure can be explained by approximately million-year periodicities in Mars' obliquity or orbital eccentricity. The observed ∼100-meter maximum deflection of the underlying substrate in response to the ice load implies that the present-day thickness of an equilibrium elastic lithosphere is greater than 300 kilometers. Alternatively, the response to the load may be in a transient state controlled by mantle viscosity. Both scenarios probably require that Mars has a subchondritic abundance of heat-producing elements.

Published
2008
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