Exploring the environments of Martian impact‐generated hydrothermal systems and their potential to support life

Abstract

Hydrothermal systems that formed as a result of impact events possess all the key requirements for life: liquid water, a supply of bio-essential elements, and potential energy sources. Therefore, they are prime locations in the search for life on other planets. Here, we apply thermochemical modeling to determine secondary mineral formation within an impact-generated hydrothermal system, using geochemical data returned for two soils on Mars found in regions that have previously experienced alteration. The computed mineral reaction pathways provide a basis for Gibbs energy calculations that enable both the identification of available geochemical energy, obtained from Fe-based redox reactions, that could be utilized by potential microbial life within these environments, and an estimate of potential cell numbers. Our results suggest that water-rock interactions occurring within impact-generated hydrothermal systems could support a range of Fe-based redox reactions. The geochemical energy produced from these reactions would be substantial and indicates that crater environments have the potential to support microbial cell numbers similar to what has been identified in terrestrial environments.

Geochemical bio-signatures in Martian analogue basaltic environments using laboratory experiments and thermochemical modelling

“…This was to ensure that the simulant contained an equivalent iron content to an average Martian basalt, which is higher than terrestrial basalts (Longhi et al, 1992), and to correct for Fe speciation. This is important when exploring Martian habitability since the Fe 2+ /Fe 3+ ratio is crucial for microbial metabolism (Nixon et al, 2013;Ramkissoon et al, 2021). Both the basalt and the aegirine were purchased from Richard Tayler Minerals (United Kingdom).…”

“…Heterotrophic microorganisms, such as Burkholderia fungorum, use organic compounds as source of energy and chemical equilibrium is more easily reached and dissolution is at minimum (Wu et al, 2007). In a mixed community, that contains also chemolithotroph microorganisms which require chemical compounds and elements (sourced from the fluid and the rock) to produce energy, dissolution rates increase due to the pH being far from equilibrium (Ramkissoon et al, 2021).…”

“…Among other places, impact-generated hydrothermal systems (Schwenzer and Kring, 2009;Marzo et al, 2010;Mangold et al, 2012;Schwenzer et al, 2012;Osinski et al, 2013;Arvidson et al, 2014;Fox et al, 2016;Turner et al, 2016) and fluvio-lacustrine systems (e.g., Gale and Jezero Craters- Grotzinger et al, 2014;Grotzinger et al, 2015;Rampe et al, 2017;Mangold et al, 2021;Tu et al, 2021) identified on Mars may have been habitable (Malin and Edgett, 2003;Abramov and Kring, 2005;Irwin et al, 2005;Mangold et al, 2012;Williams et al, 2013;Grotzinger et al, 2014;Fassett and Head, 2015) in the Noachian-early Hesperian (4.1-3.0 Ga, Grotzinger et al, 2014). It has been suggested that Gale Crater's aqueous environment had a circumneutral pH, temperatures suitable for low salinity water bodies (e.g., lake, rivers) that were stable over geological timescales, a varied chemical history and sedimentological features that can be associated with complex aqueous processes and potentially diverse redox conditions that may have been used as an energy source for life (Grotzinger et al, 2014;Bridges et al, 2015;Hurowitz et al, 2017;Edgar et al, 2020;Fraeman et al, 2020;Ramkissoon et al, 2021;Rapin et al, 2021).…”

“…In order to overcome this problem, thermochemical modelling can be used to study, theoretically, alteration processes that can occur over geological timescales. Owing to its capability to predict secondary mineral assemblages and variations in fluid chemistries by assessing reaction pathways during water-rock interactions, thermochemical modelling has been widely applied to study alteration processes that happened, or may have happened, in terrestrial and Martian aqueous environments (Griffith and Shock, 1997;Kühn, 2004;Zolotov and Mironenko, 2007;Marion et al, 2008;Bridges and Schwenzer, 2012;Catalano, 2013;Filiberto and Schwenzer, 2013;Schwenzer and Kring, 2013;Bridges et al, 2015;Melwani Daswani et al, 2016;Zolotov and Mironenko, 2016;Ramkissoon et al, 2021). Only recently, Olsson-Francis et al (2017) used thermochemical modelling in conjunction with laboratory-based experiments to investigate and compare the alteration minerals that may form during microbial basalt weathering over a range of different timescales.…”

Microbes from Brine Systems with Fluctuating Salinity Can Thrive under Simulated Martian Chemical Conditions

“…Furthermore, given the requirement for the digestion of sediment and regolith materials with hydrofluouric acid to allow their analysis with ICP-OES, and the need to prepare samples and subsequently optimize their analysis dependent on their chemical composition, ICP-OES has limited versatility in terms of future mission payload instrumentation, but may have potential application following future Mars sample return. However, shifts in fluid chemistry, as a result of the former presence of metabolic processes within ancient martian aqueous systems, would have potentially impacted on mineral formation and alteration within these systems [68], which could act as putative biosignatures [69][70][71][72]. Therefore, using ICP-OES as an analytical technique to study the impact of microbially influenced enrichment or depletion of specific chemical species within terrestrial aqueous environment simulating martian chemical conditions has the potential to inform the identification of putative biosignatures.…”