Phosphorous Availability in Mars Soil Analogues and Implications for Potential Habitability

Abstract:

If the assumption is made that any life on Mars was (or is) comparable to life on Earth then examing the functions of terrestrial organisms using Mars-like soil simulants can help project feasibility for establishing habitallity on Mars. Modern terrestrial soil microbial populations contain various species that take advantage of energy and nutrient resources such as phosphorous.[1-2]. Thermodynamic models using mineral assemblages can be useful to examine the various roles of microbes and inform how nutrient activities might be manifested given affects of metabolic products and reactants [3]. The objective of this study is to explore with thermodynamic models (Geochemist Workbench) potential availability and transofmrations of phosphorous in a Mars soil analogue [4]. Geochemical models were desgined to parallel plant growth experiments using microbial inoculants as biofertilizers that expose minerals in the Mars soil analogue to acids and bioweathering. Cheimcal, mineral, and fertility anlysis measured both total mineral phases and extractable nutrients (including phosphorous). This data along with information known from the literature of the specific microorganisms being used as biofertilizers [5-7] were used to constrain parameters in the thermodynamic models in Mars-like soil (though Earth-like atmosphere). This work can be used to inform more robust models that direclty take into account additional aspects of the early Earth and Mars environments (e.g. climate and atmospheric conditions).