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Possible role of brines in the darkening and flow-like features on the Martian polar dunes based on HiRISE images

Kereszturi, A. and Möhlmann, D. and Berczi, Sz. and Horvath, A. and Sik, A. and Szathmary, E. (2011) Possible role of brines in the darkening and flow-like features on the Martian polar dunes based on HiRISE images. Planetary and Space Science, 59 (13), pp. 1413-1427. Elsevier. DOI: 10.1016/j.pss.2011.05.012 ISSN 0032-0633

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Abstract

This work identifies and describes features of the changing seasonal frost-covered surface of Mars based on HiRISE images, and analyses the possibility that ephemeral liquid brine formation produces them. Because some of these dark features show flow-like appearance, and salts on Mars are present, liquid brines might be also present, possibly accounting for the changing droplet-like features on the Phoenix lander. We observed in-situ darkening and movement of dark features (or movement of the darkening front) on seasonal frost-covered polar dunes. Darkening and brightening may happen within several meters from each other during local spring. Darkening always starts from the bottom and moves up, while brightening progresses from top and moves toward the bottom between the small dune ripples. Brightening occurs during the spring time warming on time scales of several days close to the sites of darkening; therefore, dark material falling from the air, and refreezing of bright ice on it, does not adequately explain the observations. Interpreting the observations as brine-related melting or refreezing also poses problems, but because brine may engulf salt grains or ice blocks, phase changes here could be influenced by factors other than temperature values, and could produce the observations. Analysis of absolute albedo changes indicates that the flow-like features are the darkest at their lower frontal end, sometimes darker than the dark spot from which they originate. Abright halo (white collar) also forms around these spots, possibly due to refreezing. Inside the observed larger spots an outer gray area surrounds the central darkest cores, which is about 10 cm lower than the surrounding bright CO2 ice. At those places, most or all of the CO2 ice deposited earlier has disappeared, and H2O ice is present. Observations of dark flow features moving on the top of this H2O rich layer suggest even if the flow features start as dry dune avalanches of rolling grains, their dark material heated by solar insolation is in contact with H2O ice and may produce brines.

Item URL in elib:https://elib.dlr.de/70231/
Document Type:Article
Title:Possible role of brines in the darkening and flow-like features on the Martian polar dunes based on HiRISE images
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Kereszturi, A.Collegium Budapest, Institute for Advanced Study, Budapest, Hungary; Eotvos Lorand University of Sciences, Planetary Research Group, Institute of Geography and Earth Sciences, Budapest, HungaryUNSPECIFIED
Möhlmann, D.dirk.moehlmann (at) dlr.deUNSPECIFIED
Berczi, Sz.Collegium Budapest, Institute for Advanced Study, Budapest, Hungary; Eotvos Lorand University of Sciences, Institute of Physics; Eotvos Lorand University of Sciences, Planetary Research Group, Institute of Geography and Earth Sciences, Budapest, HungaryUNSPECIFIED
Horvath, A.Collegium Budapest, Institute for Advanced Study, Budapest, Hungary; Eotvos Lorand University of Sciences, Planetary Research Group, Institute of Geography and Earth Sciences, Budapest, Hungary; Konkoly Observatory, Budapest, HungaryUNSPECIFIED
Sik, A.Collegium Budapest, Institute for Advanced Study, Budapest, Hungary; Eotvos Lorand University of Sciences, Planetary Research Group, Institute of Geography and Earth Sciences, Budapest, HungaryUNSPECIFIED
Szathmary, E.Collegium Budapest, Institute for Advanced Study, Budapest, HungaryUNSPECIFIED
Date:2011
Journal or Publication Title:Planetary and Space Science
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:59
DOI :10.1016/j.pss.2011.05.012
Page Range:pp. 1413-1427
Publisher:Elsevier
ISSN:0032-0633
Status:Published
Keywords:Mars, surface, ice, brine, water, dune
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EW - Erforschung des Weltraums
DLR - Research area:Space
DLR - Program:W EW - Erforschung des Weltraums
DLR - Research theme (Project):W - Vorhaben Planetenforschung (old)
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research
Deposited By: Pieth, Susanne
Deposited On:28 Jun 2011 10:43
Last Modified:07 Feb 2013 20:40

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