The Distribution of Life in the Universe

McKay, Christopher P.; Trigo‐Rodríguez, Josep M.; Ehrenfreund, P.; Martín, E. L.; Lämmer, H.; Penz, T.; Belisheva, N. K.; Kulikov, Yu. N.; Biernat, H. K.; Svoboda, Josef; Lineweaver, Charles H.; Shostak, Seth; Krupička, J.; Teodorani, M.

doi:10.1007/978-1-4020-4403-8_4

Cited by 2 publications

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“…Perchlorates are of great interest to astrobiology and in particular for the habitability of Mars, for their ability to lower the freezing temperature of water ( Möhlmann and Thomsen, 2011 ) and form stable hydrated compounds and liquid solutions by absorbing atmospheric water vapor through deliquescence ( Zorzano et al, 2009 ; Nuding et al, 2014 ), which allow to create aqueous solution at the appropriate range of temperature (brines) ( Martín-Torres et al, 2015 ). The presence of an aqueous thin film could be important for a putative life-form on Mars, because water is essential for life as we known it ( McKay, 2006 ). However, the presence of perchlorates on Mars surface represents also a challenge for habitability since they can be harmful for life as we know it ( Davila et al, 2013 ; Archer et al, 2015 ; Wadsworth and Cockell, 2017 ).…”

Section: Introductionmentioning

confidence: 99%

Survival, metabolic activity, and ultrastructural damages of Antarctic black fungus in perchlorates media

2022

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Evidence from recent Mars landers identified the presence of perchlorates salts at 1 wt % in regolith and their widespread distribution on the Martian surface that has been hypothesized as a critical chemical hazard for putative life forms. However, the hypersaline environment may also potentially preserve life and its biomolecules over geological timescales. The high concentration of natural perchlorates is scarcely reported on Earth. The presence of perchlorates in soil and ice has been recorded in some extreme environments including the McMurdo Dry Valleys in Antarctica, one of the best terrestrial analogues for Mars. In the frame of “Life in space” Italian astrobiology project, the polyextremophilic black fungus Cryomyces antarcticus, a eukaryotic test organism isolated from the Antarctic cryptoendolithic communities, has been tested for its resistance, when grown on different hypersaline substrata. In addition, C. antarcticus was grown on Martian relevant perchlorate medium (0.4 wt% of Mg(ClO4)2 and 0.6 wt% of Ca(ClO4)2) to investigate the possibility for the fungus to survive in Martian environment. Here, the results indicate a good survivability and metabolic activity recovery of the black fungus when grown on four Martian relevant perchlorates. A low percentage of damaged cellular membranes have been found, confirming the ultrastructural investigation.

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Section: Introductionmentioning

confidence: 99%

Survival, metabolic activity, and ultrastructural damages of Antarctic black fungus in perchlorates media

2022

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Transient liquid water and water activity at Gale crater on Mars

et al. 2015

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Water is a requirement for life as we know it 1 . Indirect evidence of transient liquid water has been observed from orbiter on equatorial Mars 2 , in contrast with expectations from large-scale climate models. The presence of perchlorate salts, which have been detected at Gale crater on equatorial Mars by the Curiosity rover 3,4 , lowers the freezing temperature of water 5 . Moreover, perchlorates can form stable hydrated compounds and liquid solutions by absorbing atmospheric water vapour through deliquescence 6,7 . Here we analyse relative humidity, air temperature and ground temperature data from the Curiosity rover at Gale crater and find that the observations support the formation of night-time transient liquid brines in the uppermost 5 cm of the subsurface that then evaporate after sunrise. We also find that changes in the hydration state of salts within the uppermost 15 cm of the subsurface, as measured by Curiosity, are consistent with an active exchange of water at the atmosphere-soil interface. However, the water activity and temperature are probably too low to support terrestrial organisms 8 . Perchlorates are widespread on the surface of Mars 9 and we expect that liquid brines are abundant beyond equatorial regions where atmospheric humidity is higher and temperatures are lower.At the appropriate range of relative humidity and temperature, perchlorates (ClO 4 − ) deliquesce into the aqueous phase creating brines (that is, solutions of salt in water) that are stable in the liquid state. Deliquescence 6,7 occurs when, simultaneously, the ambient relative humidity (RH) is above the deliquescent relative humidity (DRH) of the deliquescent salt and the ambient temperature (T ) is above the eutectic temperature (T e ) of the resulting solution. The stability of transient aqueous salt solutions on Mars was first postulated in the 1960s 10 , and has been inferred from indirect observations at polar and near-polar regions 7,11 . The present-day activity of equatorial recurring slope lineae has been attributed to seasonal flow of brines 2 ( Supplementary Fig. 1). Nevertheless, on the basis of the large-scale predictions of global circulation models (GCMs) and the remote-sensing large-scale observation of RH and T , it is believed that deliquescence conditions could be theoretically reached on the surface of Mars only poleward of ±60 • and only during the northern spring 11,12 (when the water vapour content of the martian atmosphere peaks 13 ). Transiently stable liquid water in the form of brines was unexpected at an equatorial region 11 such as Gale (4.6 • S, 137.4 • E, at 4.5 km below the datum), where the Mars Science Laboratory (MSL) landed and has been operating since 6 August 2012.However, here we show that the RH, air temperature (T a ) and ground temperature (T g ) observations at Gale by the Rover Environmental Monitoring Station 14 (REMS) on the Curiosity rover at the MSL mission 15 are compatible with the presence of liquid brines during night time due to the increased RH associated with night-time ...

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The Distribution of Life in the Universe

Cited by 2 publications

References 24 publications

Survival, metabolic activity, and ultrastructural damages of Antarctic black fungus in perchlorates media

Survival, metabolic activity, and ultrastructural damages of Antarctic black fungus in perchlorates media

Transient liquid water and water activity at Gale crater on Mars

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