Periodic Reporting for period 3 - MarsFirstWater (The physicochemical nature of water on early Mars)
Reporting period: 2022-06-01 to 2023-11-30
Mars is the only known planetary body, other than Earth, where liquid water appears to have played a key role in its early surface evolution. However, details regarding the physicochemical nature of water and its early evolution, on both global and local scales, whether liquid or solid H2O dominated, for what duration of time, when and where, what were the host-rock weathering rates and patterns and the physicochemical parameters defining such interactions, what specific landforms and mineralogies were generated during those periods, and what implications all these processes had on the possible development of life on Mars, are still poorly developed. Many fundamental questions about aqueous processes on early Mars are still in the need of answers.
The overall objective of this investigation is to fully characterize the physicochemical nature of water on early Mars through a quantitative and truly interdisciplinary investigation. Several innovative strategies in geomorphological analysis, geochemical modeling, mineralogical studies and astrobiological investigations will fill the existing gaps, producing hard constraints on the physicochemical nature of water on early Mars. This is a truly interdisciplinary Project: all the different lines of investigation are intimately interrelated among them, and results being produced as tasks evolve will feed other research areas in a continuous internal synergy.
The results of this investigation will prove a pathfinder for other investigators’ qualitative and quantitative analyses of Martian hydrogeology, geochemistry and mineralogy, computer modelling, microbiology, and robotic mission operations and data analysis, providing opportunities to opening new paths for in situ exploration by landers and rovers.
The overall objective of this investigation is to fully characterize the physicochemical nature of water on early Mars through a quantitative and truly interdisciplinary investigation. Several innovative strategies in geomorphological analysis, geochemical modeling, mineralogical studies and astrobiological investigations will fill the existing gaps, producing hard constraints on the physicochemical nature of water on early Mars. This is a truly interdisciplinary Project: all the different lines of investigation are intimately interrelated among them, and results being produced as tasks evolve will feed other research areas in a continuous internal synergy.
The results of this investigation will prove a pathfinder for other investigators’ qualitative and quantitative analyses of Martian hydrogeology, geochemistry and mineralogy, computer modelling, microbiology, and robotic mission operations and data analysis, providing opportunities to opening new paths for in situ exploration by landers and rovers.
The work is organized in 4 Research Themes (RTs). Major scientific developments from the beginning of the project to the end of the third period (54 months) have included, in each RT:
• RT1, Geology: We have published a new geomorphological map of the Sinus Sabaeus region of Mars, providing a basis for identifying the ancient presence of water in the region, both in the liquid state and in the ice phase. We have provided the first identification of rythmites on Mars, verifying that impact events were a major source for the triggering of liquid water on early Mars. And we have documented the history of one specific aqueous episode on early Mars, providing first evidence for powerful storms, torrential rains, megafloods, and strong waves in a martian paleolake.
• RT2, Geochemistry: We have quantified how past fluids on Mars interacted with and altered the surface, depending on fluid pH, and how this alteration modified the preservation potential of organic matter embedded in clay minerals. We have reconstructed the environmental conditions that facilitated iron oxidation during the anoxic and iron-rich Archean conditions, to better understand the connection between iron mineralogy and the formation of carbonate minerals on Mars. And we have identified the limits of sensitivity and biases of several biosignature-detection instruments that are on or will be soon sent to Mars, using testbed instruments on samples from a region of the Atacama Desert with extremely low concentrations of organics.
• RT3, Mineralogy: We have provided the first identification of glauconite minerals on Mars using in situ data from the Curiosity rover, contributing to clarify how the formation of clays occurred on early Mars. We have provided the first identification of a subsoil wet clay layer in the hyperarid core of the Atacama Desert, harvesting new data to help determine the preferred mineral sequences where to look for biosignatures in the Martian subsurface. And we have developed a statistical mass-balance calculation procedure to narrow the range of chemical composition of the clay minerals and amorphous phases observed in Mars, providing the basis for their identification and subsequent interpretation of their formation environment.
• RT4, Geomicrobiology and Astrobiology: Using a novel methodology, µ-DSC, we have identified the ability of microorganisms to change the freezing/melting curve of cold salty solutions, expressing proteins that can affect the liquid-to-ice transition. We have contributed a new instrument concept to search for evidences of an ancient biosphere on Mars. And we investigated 4 Mars bioanalogs. (1) The Atacama Desert, deciphering the dispersion of microbial life using dust transported by wind, proposing the term “dark biosphere” referred to microorganisms with a high rate of phylogenetic indeterminacy, and completing the description of the metabolic strategies available to potential martian microorganisms during their adaptation to water stress. (2) Antarctica, describing the geomicrobiology of the permanently exposed lithic substrates of nunataks. (3) Rio Tinto, characterizing the microbial diversity existing in the deep subsurface of the Iberian Pyrite Belt. And (4) Tirez Lake, describing the evolution of the microbial communities during desiccation of the endorheic hypersaline lagoon, and proposing the concept of “astrobiological time-analogs”, referred to terrestrial analogs that can help understand environmental transitions and the related possible ecological successions on early Mars.
• RT1, Geology: We have published a new geomorphological map of the Sinus Sabaeus region of Mars, providing a basis for identifying the ancient presence of water in the region, both in the liquid state and in the ice phase. We have provided the first identification of rythmites on Mars, verifying that impact events were a major source for the triggering of liquid water on early Mars. And we have documented the history of one specific aqueous episode on early Mars, providing first evidence for powerful storms, torrential rains, megafloods, and strong waves in a martian paleolake.
• RT2, Geochemistry: We have quantified how past fluids on Mars interacted with and altered the surface, depending on fluid pH, and how this alteration modified the preservation potential of organic matter embedded in clay minerals. We have reconstructed the environmental conditions that facilitated iron oxidation during the anoxic and iron-rich Archean conditions, to better understand the connection between iron mineralogy and the formation of carbonate minerals on Mars. And we have identified the limits of sensitivity and biases of several biosignature-detection instruments that are on or will be soon sent to Mars, using testbed instruments on samples from a region of the Atacama Desert with extremely low concentrations of organics.
• RT3, Mineralogy: We have provided the first identification of glauconite minerals on Mars using in situ data from the Curiosity rover, contributing to clarify how the formation of clays occurred on early Mars. We have provided the first identification of a subsoil wet clay layer in the hyperarid core of the Atacama Desert, harvesting new data to help determine the preferred mineral sequences where to look for biosignatures in the Martian subsurface. And we have developed a statistical mass-balance calculation procedure to narrow the range of chemical composition of the clay minerals and amorphous phases observed in Mars, providing the basis for their identification and subsequent interpretation of their formation environment.
• RT4, Geomicrobiology and Astrobiology: Using a novel methodology, µ-DSC, we have identified the ability of microorganisms to change the freezing/melting curve of cold salty solutions, expressing proteins that can affect the liquid-to-ice transition. We have contributed a new instrument concept to search for evidences of an ancient biosphere on Mars. And we investigated 4 Mars bioanalogs. (1) The Atacama Desert, deciphering the dispersion of microbial life using dust transported by wind, proposing the term “dark biosphere” referred to microorganisms with a high rate of phylogenetic indeterminacy, and completing the description of the metabolic strategies available to potential martian microorganisms during their adaptation to water stress. (2) Antarctica, describing the geomicrobiology of the permanently exposed lithic substrates of nunataks. (3) Rio Tinto, characterizing the microbial diversity existing in the deep subsurface of the Iberian Pyrite Belt. And (4) Tirez Lake, describing the evolution of the microbial communities during desiccation of the endorheic hypersaline lagoon, and proposing the concept of “astrobiological time-analogs”, referred to terrestrial analogs that can help understand environmental transitions and the related possible ecological successions on early Mars.
Most significant advances: (1) a novel mapping of water and water ice during the Noachian near the Martian dichotomy; (2) the first identification of rythmites on Mars; (3) the first quantification of the effects of fluid pH on the capability of clays to preserve organics; (4) the identification of sensitivity limits of biosignature-detection instruments landed on Mars; (5) the identification of the environmental conditions that facilitated iron oxidation during the anoxic and iron-rich Archean conditions; (6) the first detection of glauconites on Mars; (7) the discovery of subsurface wet and inhabited clays in Atacama as analogs to the Martian subsoil; (8) the identification of a metabolic pathway by which microorganisms may increase the habitability of cold salty solutions; (9) the introduction of the concepts “dark biosphere” and “astrobiological time-analog”; and (10) the proposal of a new astrobiological instrument to search for biomarkers on Mars (our paper describing this instrument received the “EANA 2021 Outstanding Paper Award”).
Expected results: (1) Quantifying the thickness and volume of the stratigraphic sequence of volcanic infilling of the Martian lowlands, to determine the volume of the lowlands and therefore enhancing our understanding of the global hydrological cycle and water inventory for ancient Mars. (2) Applying our previously developed dynamic model of Li-isotope fractionation during silicate weathering under Martian conditions to a representative bedrock composition in Gale crater, to increase our understanding of the local-scale geochemical evolution of hydrated mineral sequences on early Mars. (3) Advancing understanding of the evolution and modification of the Martian surface, in particular the inventory of volatiles in the Martian early silicate crust and how past fluids interacted with and altered the surface. And (4) characterizing representative microbial model species from cold environments, in order to understand how life was able to adapt to the desiccation stress induced by freezing as a model for possible inhabited environments on early Mars.
Expected results: (1) Quantifying the thickness and volume of the stratigraphic sequence of volcanic infilling of the Martian lowlands, to determine the volume of the lowlands and therefore enhancing our understanding of the global hydrological cycle and water inventory for ancient Mars. (2) Applying our previously developed dynamic model of Li-isotope fractionation during silicate weathering under Martian conditions to a representative bedrock composition in Gale crater, to increase our understanding of the local-scale geochemical evolution of hydrated mineral sequences on early Mars. (3) Advancing understanding of the evolution and modification of the Martian surface, in particular the inventory of volatiles in the Martian early silicate crust and how past fluids interacted with and altered the surface. And (4) characterizing representative microbial model species from cold environments, in order to understand how life was able to adapt to the desiccation stress induced by freezing as a model for possible inhabited environments on early Mars.