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Masson, Philippe; Carr, M. H.; Costard, F.; Greeley, R.; Hauber, Ernst; Jaumann, R.

doi:10.1023/a:1011913809715

Cited by 39 publications

(3 citation statements)

References 152 publications

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“…Several observations on Mars, such as characteristic surface morphologies like large fluid-eroded channels, dendritic networks, fluvial valleys, and glacial features [1], and the formation of water-depending minerals like hematite [2], indicate that the planet had a warmer (even though mostly freezing [3]), wetter and more habitable climate in its early history [4]. However, the loss of its magnetic field enabled the solar wind to sputter away large parts of the Martian atmosphere which caused a climate change leading to the dry, cold, and hostile planet that we know today [5,6].…”

Section: Introductionmentioning

confidence: 99%

A New Record for Microbial Perchlorate Tolerance: Fungal Growth in NaClO4 Brines and its Implications for Putative Life on Mars

Heinz

Krahn

Schulze‐Makuch

2020

Life

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The habitability of Mars is strongly dependent on the availability of liquid water, which is essential for life as we know it. One of the few places where liquid water might be found on Mars is in liquid perchlorate brines that could form via deliquescence. As these concentrated perchlorate salt solutions do not occur on Earth as natural environments, it is necessary to investigate in lab experiments the potential of these brines to serve as a microbial habitat. Here, we report on the sodium perchlorate (NaClO4) tolerances for the halotolerant yeast Debaryomyces hansenii and the filamentous fungus Purpureocillium lilacinum. Microbial growth was determined visually, microscopically and via counting colony forming units (CFU). With the observed growth of D. hansenii in liquid growth medium containing 2.4 M NaClO4, we found by far the highest microbial perchlorate tolerance reported to date, more than twice as high as the record reported prior (for the bacterium Planococcus halocryophilus). It is plausible to assume that putative Martian microbes could adapt to even higher perchlorate concentrations due to their long exposure to these environments occurring naturally on Mars, which also increases the likelihood of microbial life thriving in the Martian brines.

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Section: Introductionmentioning

confidence: 99%

A New Record for Microbial Perchlorate Tolerance: Fungal Growth in NaClO4 Brines and its Implications for Putative Life on Mars

Heinz

Krahn

Schulze‐Makuch

2020

Life

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“…The existence of water on Mars has long been controversial. Some evidence has shown that water disappeared from the Mars surface after its formation [17,26,27]. Although the whereabouts of the water have long been debated, some parts of the hydrated crust of Mars may have been brought into the deep interior by the convecting mantle.…”

Section: Discussionmentioning

confidence: 99%

Phase Relations in MAFSH System up to 21 GPa: Implications for Water Cycles in Martian Interior

Inoue

2019

Minerals

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To elucidate the water cycles in iron-rich Mars, we investigated the phase relation of a water-undersaturated (2 wt.%) analog of Martian mantle in simplified MgO-Al 2 O 3 -FeO-SiO 2 -H 2 O (MAFSH) system between 15 and 21 GPa at 900-1500 • C using a multi-anvil apparatus. Results showed that phase E coexisting with wadsleyite or ringwoodite was at least stable at 15-16.5 GPa and below 1050 • C. Phase D coexisted with ringwoodite at pressures higher than 16.5 GPa and temperatures below 1100 • C. The transition pressure of the loop at the wadsleyite-ringwoodite boundary shifted towards lower pressure in an iron-rich system compared with a hydrous pyrolite model of the Earth. Some evidence indicates that water once existed on the Martian surface on ancient Mars. The water present in the hydrous crust might have been brought into the deep interior by the convecting mantle. Therefore, water might have been transported to the deep Martian interior by hydrous minerals, such as phase E and phase D, in cold subduction plates. Moreover, it might have been stored in wadsleyite or ringwoodite after those hydrous materials decomposed when the plates equilibrated thermally with the surrounding Martian mantle.when reacting with overlying hydrous crust, bringing water into the deep interior [17]. Therefore, similarly to an Earth-like planet, some hydrous minerals might exist in cold region of iron-rich Mars, and wadsleyite and ringwoodite might also hold a huge amount of water in the Martian interior, as it was argued for the present-day Earth.Several studies have identified phase relations in the MSH and MgO-Al 2 O 3 -SiO 2 -H 2 O (MASH) systems, with the observation of various hydrous minerals at P-T conditions related to the cold subduction slabs [3,4,6,7,18,19]. Nevertheless, few data are available for hydrous iron-bearing systems: data for iron-rich systems, such as Mars, are rarely reported [5]. A better understanding of the phase relations in MgO-Al 2 O 3 -FeO-SiO 2 -H 2 O (MAFSH) system might help to elucidate the geodynamic processes associated with the deepwater cycles of Mars. Therefore, we determined the phase relations in iron-rich MAFSH system between 15 GPa and 21 GPa to systematically ascertain the stability of DHMSs, and further estimate the possible water transportation into the Martian interior by subducting processes.

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“…When assessing the habitability of present-day Mars, various environmental factors come into play, among which the availability of water and the radiation environment on and near the surface are crucial considerations 1 . Although there is compelling evidence indicating that Mars once hosted substantial bodies of liquid water, as evidenced by geomorphological features on the surface of Mars 2 , the current conditions render liquid water largely unstable on its surface 3 . However, liquid water could be temporarily stable on and near the surface of present-day Mars in the form of liquid brines 4 , which could be formed either through the contact of salts with water ice, which is supported by experimental evidence 5 , or through a process called deliquescence, in which a hygroscopic salt absorbs water from the atmosphere and dissolves in the absorbed liquid.…”

Section: Introductionmentioning

confidence: 99%

Microbial preference for chlorate over perchlorate under simulated shallow subsurface Mars-like conditions

Fischer,

Schulze-Makuch,

Heinz

2024

Sci Rep

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The Martian surface and shallow subsurface lacks stable liquid water, yet hygroscopic salts in the regolith may enable the transient formation of liquid brines. This study investigated the combined impact of water scarcity, UV exposure, and regolith depth on microbial survival under Mars-like environmental conditions. Both vegetative cells of Debaryomyces hansenii and Planococcus halocryophilus, alongside with spores of Aspergillus niger, were exposed to an experimental chamber simulating Martian environmental conditions (constant temperatures of about − 11 °C, low pressure of approximately 6 mbar, a CO2 atmosphere, and 2 h of daily UV irradiation). We evaluated colony-forming units (CFU) and water content at three different regolith depths before and after exposure periods of 3 and 7 days, respectively. Each organism was tested under three conditions: one without the addition of salts to the regolith, one containing sodium chlorate, and one with sodium perchlorate. Our results reveal that the residual water content after the exposure experiments increased with regolith depth, along with the organism survival rates in chlorate-containing and salt-free samples. The survival rates of the three organisms in perchlorate-containing regolith were consistently lower for all organisms and depths compared to chlorate, with the most significant difference being observed at a depth of 10–12 cm, which corresponds to the depth with the highest residual water content. The postulated reason for this is an increase in the salt concentration at this depth due to the freezing of water, showing that for these organisms, perchlorate brines are more toxic than chlorate brines under the experimental conditions. This underscores the significance of chlorate salts when considering the habitability of Martian environments.

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Untitled

Cited by 39 publications

References 152 publications

A New Record for Microbial Perchlorate Tolerance: Fungal Growth in NaClO4 Brines and its Implications for Putative Life on Mars

A New Record for Microbial Perchlorate Tolerance: Fungal Growth in NaClO4 Brines and its Implications for Putative Life on Mars

Phase Relations in MAFSH System up to 21 GPa: Implications for Water Cycles in Martian Interior

Microbial preference for chlorate over perchlorate under simulated shallow subsurface Mars-like conditions

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