Image: Merve Yeşilbaş
Research project financed by the Swedish Research Council.
Previous missions to Mars confirmed the presence of varied types of chloride and perchlorate salts in the martian regolith all over the planet. Due to their unique deliquescence properties, these salts could facilitate the formation of liquid salty brines well below 0 °C. Thesy could also be formed and stabilized within aggregates of mineral particles in the regolith by forming thin water ice films. This project aims to reveal (liquid) water stability on modern Mars to understand aqueous geochemistry and potential water resource regions that could have hosted life if it was ever present there.
Mars seems like a frozen desert today, exposed to extreme UV radiation and surrounded by a very thin atmospheric layer in comparison to Earth. These extreme conditions on Mars allow only ice and vapour on the surface. However, the salts can depress the freezing point of water well below 0 °C allowing to form salty brines corresponding to their specific deliquescence features. The near-surface environments of Mars can facilitate the formation and stabilization of these salty brines, specifically with the help of the martian regolith. Advancing that, the overall aim of this research is to investigate the (liquid) water stability on modern Mars to understand its aqueous geochemical history, climate, and habitability, as well as to reveal potential water resources for future human explorations on the Red Planet.
My recent study with martian analogue-CaCl2 rich mixtures revealed that salt/Martian analogue mixtures can host liquid water and brine in the -50 to -30 °C range, a result indicating that chemical activity may be possible below the surface of Mars today. I hypothesize that the chloride could be reacting to form an oxychloride phase because this would be expected to be partially liquid at cold temperatures within the soil matrix. However, the actual role of regoliths in this process is still not well resolved.
Advancing that, we will address the following 3 key questions to gain a fundamental understanding of the formation of thin water ice films on the near surface of Mars:
1) What are the onset temperatures to form thin water films in varied martian analogue-Cl-salt mixtures?
2) How do the varied type of Cl-salts including chlorides and perchlorates, and their mixtures enable to form possible oxychloride/oxychlorate phases in salty martian analogue mixtures?
3) What are the physical and chemical parameters effecting the water stability on near surface of Mars that applicable to the martian geochemical observations from the orbit data?
These questions will be answered by evaluating the roles of (i) Cl-salt abundance, (ii) particle (grain) size distribution, and (iii) the chemical composition of the martian analogue materials. We will perform low-temperature vibrational spectroscopy (Raman, VNIR, and mid-IR reflectance) experiments with these salty martian analogues, mimicking the repeated martian diurnal cycle from cold to high temperatures. To the best of my knowledge, this will be the very first study testing the possibility of oxychloride/oxychlorate phase formation in martian analogue soils and their water stabilization ability on Mars using Raman and VNIR spectroscopy at low temperatures.
Then, our laboratory results will be compared with Compact Reconnaissance Impact Imaging Spectrometer for Mars (CRISM) remote sensing data. Here, we will gain a better understanding of modern Mars geochemistry by taking advantage of CRISM’s recently developed new image noise reduction and hyperspectral image calibrations.
This research will provide a fundamental understanding of Mars geochemistry and greatly develop observations of ice and brine formation on Mars. Furthermore, our results will provide a new pathway for experimentalists and modelers to understand stabilized liquid water on Mars and its availability for life. This will be particularly important to support the ongoing and upcoming Mars rover and orbital missions of the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA).
