Observations of the northern seasonal polar cap on Mars: I. Spring sublimation activity and processes

Hansen, C. J.; Byrne, S.; Portyankina, Ganna; Bourke, M. C.; Dundas, C. M.; McEwen, A. S.; Mellon, M. T.; Pommerol, Antoine; Thomas, N.

doi:10.1016/j.icarus.2012.09.024

Cited by 115 publications

(48 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1c; e.g. Diniega et al 2010;Hansen et al 2011Hansen et al , 2013Dundas et al 2012Dundas et al , 2015Harrison et al 2015); and (3) 'linear dune gullies' (Fig. 1d; e.g.…”

Section: Stability Of Liquid Water At the Surface Of Marsmentioning

confidence: 99%

“…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%

See 1 more Smart Citation

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

Herny

Conway

Raack

et al. 2018

View full text Add to dashboard Cite

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...

show abstract

“…1c; e.g. Diniega et al 2010;Hansen et al 2011Hansen et al , 2013Dundas et al 2012Dundas et al , 2015Harrison et al 2015); and (3) 'linear dune gullies' (Fig. 1d; e.g.…”

Section: Stability Of Liquid Water At the Surface Of Marsmentioning

confidence: 99%

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

View full text Add to dashboard Cite

show abstract

“…8). These furrows appear reminiscent of 'spider'-like channels that form due to gas flow beneath a solid ice layer (Bourke & Cranford 2011;Diniega et al 2013;Hansen et al 2013). Although a full investigation of the formation process of these features is outside of our current study, this type of feature suggests that the seasonal frost layer over these dunes has solidified into an icy layer.…”

Section: Observed Alcove Activity When the Alcoves Formmentioning

confidence: 80%

Dune-slope activity due to frost and wind throughout the north polar erg, Mars

Diniega

Hansen

Allen

et al. 2017

View full text Add to dashboard Cite

Repeat, high-resolution imaging of dunes within the Martian north polar erg have shown that these dune slopes are very active, with alcoves forming along the dune brink each Mars year. In some areas, a few hundred cubic metres of downslope sand movement have been observed, sometimes moving the dune brink 'backwards'. Based on morphological and activity-timing similarities of these north polar features to southern dune gullies, identifying the processes forming these features is likely to have relevance for understanding the general evolution/modification of dune gullies. To determine alcove-formation model constraints, we have surveyed seven dune fields, each over 1-4 Mars winters. Consistent with earlier reports, we found that alcove-formation activity occurs during the autumn-winter seasons, before or while the stable seasonal frost layer is deposited. We propose a new model in which alcove formation occurs during the autumn, and springtime sublimation activity then enhances the feature. Summertime winds blow sand into the new alcoves, erasing small alcoves over a few Mars years. Based on the observed rate of alcove erasure, we estimated the effective aeolian sand transport flux. From this, we proposed that alcove formation may account for 2-20% of the total sand movement within these dune fields.

show abstract

“…Bottom "Swiss-cheese terrains" due to sublimation of the CO 2 cap (MRO/JPL/UA/LPL/HiRISE) et al 2011). The effect of defrosting is spectacular on dark sand dunes where the large decrease in albedo is huge and produces a sudden warming that enhances the process (Kossacki and Leliwa-Kopystynski 2004;Gardin et al 2010;Hansen et al 2010Hansen et al , 2013. Most of these features are seasonal and disappear after the surface is defrosted, but the long-term effect of CO 2 defrosting on martian landscape evolution is not yet fully understood.…”

Section: Seasonal and Polar Processesmentioning

confidence: 99%

Mars: a small terrestrial planet

Mangold

Baratoux

Witasse

et al. 2016

Astron Astrophys Rev

View full text Add to dashboard Cite

Mars is characterized by geological landforms familiar to terrestrial geologists. It has a tenuous atmosphere that evolved differently from that of Earth and Venus and a differentiated inner structure. Our knowledge of the structure and evolution of Mars has strongly improved thanks to a huge amount of data of various types (visible and infrared imagery, altimetry, radar, chemistry, etc) acquired by a dozen of missions over the last two decades. In situ data have provided ground truth for remote-sensing data and have opened a new era in the study of Mars geology. While large sections of Mars science have made progress and new topics have emerged, a major question in Mars exploration-the possibility of past or present life-is still unsolved. Without entering into the debate around the presence of life traces, our review develops various topics of Mars science to help the search of life on Mars, building on the most recent discoveries, going from the exosphere to the interior structure, from the magmatic evolution to the currently active processes, including the fate of volatiles and especially liquid water.

show abstract

Observations of the northern seasonal polar cap on Mars: I. Spring sublimation activity and processes

Cited by 115 publications

References 58 publications

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

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

Dune-slope activity due to frost and wind throughout the north polar erg, Mars

Mars: a small terrestrial planet

Contact Info

Product

Resources

About