Long lasting habitable periods in Gale crater constrained by glauconitic clays.

In situ investigations by the Mars Science Laboratory, rover, have confirmed the presence of an ancient lake in Gale crater for up to 10 million years. The lake was filled with sediments that eventually converted to a compacted sandstone. However, it remains unclear whether the infilling of the lake was the result of background sedimentation processes or represents punctual flooding events in a largely isolated lake.

Constraining the preservation of organic compounds in Mars analog nontronites after exposure to acid and alkaline fluids.

The presence of organic matter in lacustrine mudstone sediments at Gale crater was revealed by the Mars Science Laboratory Curiosity rover, which also identified smectite clay minerals. Analogue experiments on phyllosilicates formed under low temperature aqueous conditons have illustrated that these are excellent reservoirs to host organic compounds against the harsh surface conditions of Mars. Here, we evaluate whether the capacity of smectites to preserve organic compounds can be influenced by a short exposure to different diagenetic fluids.

Can Halophilic and Psychrophilic Microorganisms Modify the Freezing/Melting Curve of Cold Salty Solutions? Implications for Mars Habitability.

We present the hypothesis that microorganisms can change the freezing/melting curve of cold salty solutions by protein expression, as it is known that proteins can affect the liquid-to-ice transition, an ability that could be of ecological advantage for organisms on Earth and on Mars. We tested our hypothesis by identifying a suitable candidate, the well-known psycrophile and halotolerant bacteria sp. JG3, and analyzing its response in culture conditions that included specific hygroscopic salts relevant to Mars-that is, highly concentrated magnesium perchlorate solutions of 20 wt % and 50 wt % Mg(ClO) at both end members of the eutectic concentration (44 wt %)-and subfreezing temperatures (263 K and 253 K).

Detection of Potential Lipid Biomarkers in Oxidative Environments by Raman Spectroscopy and Implications for the ExoMars 2020-Raman Laser Spectrometer Instrument Performance.

The aim of the European Space Agency's ExoMars rover mission is to search for potential traces of present or past life in the swallow subsurface (2 m depth) of Mars. The ExoMars rover mission relies on a suite of analytical instruments envisioned to identify organic compounds with biological value (biomarkers) associated with a mineralogical matrix in a highly oxidative environment. We investigated the feasibility of detecting basic organics (linear and branched lipid molecules) with Raman laser spectroscopy, an instrument onboard the ExoMars rover, when exposed to oxidant conditions.

Mineral paragenesis on Mars: The roles of reactive surface area and diffusion.

Geochemical models of secondary mineral precipitation on Mars generally assume semiopen systems (open to the atmosphere but closed at the water-sediment interface) and equilibrium conditions. However, in natural multicomponent systems, the reactive surface area of primary minerals controls the dissolution rate and affects the precipitation sequences of secondary phases, and simultaneously, the transport of dissolved species may occur through the atmosphere-water and water-sediment interfaces. Here we present a suite of geochemical models designed to analyze the formation of secondary minerals in basaltic sediments on Mars, evaluating the role of (i) reactive surface areas and (ii) the transport of ions through a basalt sediment column.

Tracking the weathering of basalts on Mars using lithium isotope fractionation models.

Lithium (Li), the lightest of the alkali elements, has geochemical properties that include high aqueous solubility (Li is the most fluid mobile element) and high relative abundance in basalt-forming minerals (values ranking between 0.2 and 12 ppm). Li isotopes are particularly subject to fractionation because the two stable isotopes of lithium-Li and Li-have a large relative mass difference (∼15%) that results in significant fractionation between water and solid phases.

Pyrite nanoparticles as a Fenton-like reagent for in situ remediation of organic pollutants.

The Fenton reaction is the most widely used advanced oxidation process (AOP) for wastewater treatment. This study reports on the use of pyrite nanoparticles and microparticles as Fenton reagents for the oxidative degradation of copper phthalocyanine (CuPc) as a representative contaminant. Upon oxidative dissolution in water, pyrite (FeS2) particles can generate H2O2 at their surface while simultaneously promoting recycling of Fe(3+) into Fe(2+) and vice versa.