Abstract_EANA2025-126

Abstract EANA2025-126

Longevity of Hydrological Regime and Water Activity as Important Parameters in Search for Astrobiological Target Sites

Deepali Singh (1,2), Kinsuk Acharyya (2), Rishitosh K. Sinha (2), Eloi Camprubi (3) and Tian Dong (4)

(1)Office of Research, University of Texas Rio Grande Valley, USA (2)Planetary Science Division, Physical Research Laboratory, Dept. of Space, India (3)School of Integrative Biological and Chemical Sciences, University of Texas Rio Grande Valley, USA (4)School of Earth, Environmental, and Marine Sciences, University of Texas Rio Grande Valley, USA

Introduction: For a long time, there has been a search for evidence of water in the Martian past since it is the main solvent of all life on Earth. In this context, certain chlorides have shown the potential to provide a harbour for microbes to survive and propagate in extreme conditions [1,2]. This work, therefore, explored a chloride-rich sedimentary basin within the Terra Sirenum region of Mars [3-6] and reconstructed its hydrological regime to understand its potential as an astrobiological target site.

Methods: The habitability potential of an area is a function of a conducive environment and the longevity of those sustainable conditions [4]. To ascertain the duration of hydrological activity we carried out fluid and sediment discharge analysis [7,8] using ConTeXt (CTX) Camera its Digital Elevation Model [9,10]and subsequently modelled the availability of water, or water activity, within the basin by considering it as a multicomponent system [11] and deriving the ionic forms from its mineralogical profile.

Results and discussion: Sediment transport modelling of the surrounding network of valleys suggested that the basin was hydrologically active for more than ten thousand years with periods of drying and wetting. We categorized the possibility for habitability into three fields using two isolines at 0.75 [12,13] and 0.55 based on the saturation points of the dominant chloride species and the lowest known limit of life, i.e., 0.565 [14,15]. Water activity modelling of the system and its comparison with Earth-based playas suggested the mineralogical combination of the basin does not adversely decrease the availability of water (i.e., beyond 0.75) for living systems, since microorganisms have been found in even poorer environments on Earth.

Conclusion: We propose that the duration of the hydrological regime within an area and ions conducive to high water activity must be included as important factors for site selection for future astrobiologically oriented missions.

References: [1] Davila et al. (2008). JGR: Biogeosci. 113 (1), 1–9. [2] Wierzchos et al. (2011). Geobiology, 9(1), 44–60. [3] Osterloo et al. (2008). Sci., 319(5870), 1651-1654. [4] Osterloo et al. (2010). JGR: Planets, 115(E10). [5] Singh et al. (2023). LPS., Abstract #2806. [6] Singh et al. (2024). Manuscript submitted. [7] Kleinhans (2005). JGR: Planets, 11(E12). [8] Wilson et al. (2004). JGR: Planets, 109(E9). [9] Malin et al. (2007). JGR: Planets, 112 (E5). [10] Quantin-Nataf et al. (2018). Planet. and Sp. Sci., 150, 157-170. [11] Pitzer (1991). CRC Press, 75-153. [12] Grant (2004). Phil. Trans. of the Royal Soc. Lon. B: Bio. Sci., 359(1448), 1249–1267. [13] Lee et al. (2018). FEMS Micro. Rev., 42(5), 672–693. [14] Stevenson et al. (2015). ISME Jour., 9, 1-19. [15] Stevenson et al. (2017). Env. Micro., 19(2), 687-97.