Recent rheologic processes on dark polar dunes of Mars: Driven by interfacial water?

Keresztúri, A.; Möhlmann, D.; Bérczi, Sz.; Gánti, T.; Kuti, A.; Sik, A.; Horváth, András

doi:10.1016/j.icarus.2009.01.014

Cited by 58 publications

(27 citation statements)

References 26 publications

(2 reference statements)

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“…However, Martinez et al (2012) show that these explanations are unlikely. Kereszturi et al (2009) suggest that ULI water may cause the growth of FLF shown in Fig. 6.…”

Section: Dune Dark Spots and Flow-like Featuresmentioning

confidence: 89%

Water and Brines on Mars: Current Evidence and Implications for MSL

2013

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Liquid water is a basic ingredient for life as we know it. Therefore, in order to understand the habitability of other planets we must first understand the behavior of water on them. Mars is the most Earth-like planet in the solar system and it has large reservoirs of H 2 O. Here, we review the current evidence for pure liquid water and brines on Mars, and discuss their implications for future and current missions such as the Mars Science Laboratory.Neither liquid water nor liquid brines are currently stable on the surface of Mars, but they could be present temporarily in a few areas of the planet. Pure liquid water is unlikely to be present, even temporarily, on the surface of Mars because evaporation into the extremely dry atmosphere would inhibit the formation of the liquid phase, where the temperature and pressure are high enough so that water would neither freeze nor boil. The exception to this is that monolayers of liquid water, referred to as undercooled liquid interfacial water, could exist on most of the Martian surface. In a few places liquid brines could exist temporarily on the surface because they could form at cryogenic temperatures, near ice or frost deposits where sublimation could be inhibited by the presence of nearly saturated air.Both liquid water and liquid brines might exist in the shallow subsurface because even a thin layer of soil forms an effective barrier against sublimation allowing pure liquid water to form sporadically in a few places, or liquid brines to form over longer periods of time in large portions of the planet. At greater depths, ice deposits could melt where the soil conductivity is low enough to blanket the deeper subsurface effectively. This could cause the formation of aquifers if the deeper soil is sufficiently permeable and an impermeable layer exists below the source of water.The fact that liquid brines and groundwater are likely to exist on Mars has important implications for geochemistry, glaciology, mineralogy, weathering and the habitability of Mars.

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“…However, Martinez et al (2012) show that these explanations are unlikely. Kereszturi et al (2009) suggest that ULI water may cause the growth of FLF shown in Fig. 6.…”

Section: Dune Dark Spots and Flow-like Featuresmentioning

confidence: 89%

Water and Brines on Mars: Current Evidence and Implications for MSL

2013

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“…According to these surface temperatures and depending on the concentration and salts involved, a similar behaviour is expected for the brines as observed in our pure water experiments for slightly higher surface temperatures. (2) Dark dune flows (Fenton et al 2003;Kieffer et al 2006;Horvath et al 2009;Kereszturi et al 2009;Gardin et al 2010Hansen et al 2011Hansen et al , 2013 are several tens of metres long and metres wide emanating from Dark Dune Spots and they form during local spring at low temperatures (150-180 K; Kereszturi et al 2010) The leading hypothesis for the dark flows is that the material deposited in the dark spots is remobilized by ongoing sublimation of CO 2 slab ice (Gardin et al 2010). An alternative hypothesis is that these dark flows are caused by viscous liquid film flow Kereszturi et al 2010).…”

Section: Implication For Martian Landscape Studiesmentioning

confidence: 99%

Downslope sediment transport by boiling liquid water under Mars-like conditions: experiments and potential implications for Martian gullies

Herny

Conway

Raack

et al. 2018

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Gullies are widespread morphological features on Mars for which current changes have been observed. Liquid water has been one of the potential mechanisms to explain their formation and activity. However, under present-day Martian conditions, liquid water is unstable and should only be transiently present in small amounts at the surface. Yet little attention has been paid to the mechanisms by which unstable water transports sediment under low atmospheric pressure. Here we present the results of laboratory experiments studying the interaction between liquid water flowing over a sand bed under Mars-like atmospheric pressure (c. 9 mbar). The experiments were performed in a Mars Simulation Chamber (at the Open University, UK), in which we placed a test bed of fine sand at a 25°slope. We chose to investigate the influence of two parameters: the temperature of the water and the temperature of the sand. We performed 27 experiments with nine different combinations of water and sand temperatures ranging from 278 to 297 K. Under all experimental conditions, the water was boiling. We investigated and compared the types and timing of sediment transport events, and the shapes, characteristics and volumes of the resulting morphologies. In agreement with previous laboratory studies we found that more intense boiling increased the volume of sediment transported for a given volume of water. We found four main types of sediment transport: entrainment by overland flow; grain ejection; grain avalanches; and levitation of saturated sand pellets. Our results showed that increasing sand temperature was the main driving parameter in increasing the sand transport and in modifying the dominant sediment transport mechanism. The temperature of the water played a negligible or minor role, apart from the duration of sand ejection and avalanches, which lasted longer at low water temperature. At low sand temperature the majority of the sand was transported by overland flow of the liquid water. At higher sand temperatures the transport was dominated by processes triggered by the boiling behaviour of the water. At the highest temperatures, sediment transport was dominated by the formation of levitating pellets, dry avalanches and ejection of the sand grains. This resulted in a transport volume about nine times greater at a sand temperature of 297 K compared with 278 K. Our heat transfer scaling shows that the boiling behaviour will be enhanced under Martian low gravity, resulting in more efficient transport of sediment by levitating sand pellets even at temperatures close to the triple point. Our results showed that the boiling intensity played an important role in the physics of sediment transport by liquid water. This implied that the amount of water required to produce morphological changes at the surface of Mars could be lower than previously estimated by assuming stable liquid water. Boiling is a critical process to be considered when assessing gully formation and modification mechanisms mobilized by liquid water. Our work could ha...

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“…Two types of dark spots have been observed on southern polar dunes: large dark spots, typically > 20 m in diameter, which form on flat surfaces between dunes, and smaller dark spots that form on dune ridges (Kereszturi et al, 2011). Flowlike features may emanate from the dark spots that form on dune ridges (Kereszturi et al, 2009).…”

Section: Introductionmentioning

confidence: 99%