Abstract_EANA2024-39

Abstract EANA2024-39

The role of sulfates in the organic preservation on Mars: UV irradiation of carboxylic acids and PAHs in hydrated magnesium sulfate.

Andrew Alberini (1,2), Teresa Fornaro (1), Cristina García Florentino (1,3), Malgorzata Biczysko (4), Iratxe Poblacion (3), Julene Aramendia (3), Juan Manuel Madariaga (3), Giovanni Poggiali (1,5), Álvaro Vicente-Retortillo (6), Kathleen C. Benison (7), Sandra Siljeström (8), Sole Biancalani (1,9,10,11), Christian Lorenz (1,12), Edward A. Cloutis (13), Dan M. Applin (13), Felipe Gómez (6), Andrew Steele (14), Roger C. Wiens (15), Kevin P. Hand (16) & John R. Brucato (1)

(1) INAF- Astrophysical Observatory of Arcetri, L.go E. Fermi 5, 50125 Firenze, Italy; (2) Department of Physics and Astronomy, University of Florence, Via Giovanni Sansone 1, 50019 Sesto Fiorentino, Florence; (3) Department of Analytical Chemistry, University of the Basque Country UPV/EHU, 48080 Bilbao, Spain; (4) College of Science, Shanghai University, 99 Shangda Road, Shanghai 200444, China; (5) LESIA - Observatoire de Paris, Université Paris Cité, Université PSL, Sorbonne Université, CNRS, 5 place Jules Janssen, 92190 Meudon, France; (6) Centro de Astrobiología (CAB), CSIC-INTA, Torrejón de Ardoz, Spain; (7) Department of Geology and Geography, West Virginia University, Morgantown, WV, USA; (8) RISE Research Institutes of Sweden, Stockholm, Sweden; (9) Department of Physics, University of Trento, Via Sommarive 14, 38123 Povo; (10) Italian Space Angency (ASI), viale del Politecnico snc, 00133, Rome, Italy; (11) Department of Earth Sciences, University of Florence, via G. La Pira 4, 50121, Florence, Italy; (12) Department of Biology, University of Naples Federico II, Via Cinthia, 80126 Naples, Italy; (13) Centre for Terrestrial and Planetary Exploration, University of Winnipeg, Winnipeg, Manitoba R3B 2E9, Canada; (14) Carnegie Institute for Science, Washington, DC, USA; (15) Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN, USA; (16) Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA.

The main criterion for evaluating the astrobiological value of Martian samples collected by the NASA Mars 2020 Perseverance rover at Jezero crater is the presence of minerals with a high potential for preserving biosignatures and organic matter. Perseverance studies the mineral and organic content of rocks by abrading their surfaces and analyzing the subsurface material using its instruments. Due to operational requirements, these abraded patches are exposed to Martian surface conditions for at least one sol before being measured with proximity science instruments. At this timescale it is possible for solar ultraviolet (UV) photons in the 200-400 nm wavelength range to alter organic matter within the abrasion [1]. The SHERLOC instrument onboard Perseverance has detected the most intense signals possibly due to aromatic organic compounds associated with minerals that have undergone significant aqueous processing, such as sulfates and carbonates [2][3]. In this work, we investigated the potential photoprotective behavior of magnesium sulfate towards organic compounds likely present on Mars, such as carboxylic acids, and polycyclic aromatic hydrocarbons (PAHs). We prepared Martian analog samples simulating a potential natural interaction in an early Martian aqueous environment between magnesium sulfate and the aforementioned organics, followed by a plausible desiccation event [4]. These Martian analog samples were characterized using a Bruker VERTEX 70v FTIR interferometer (Diffuse Reflectance Infrared Fourier Transform, DRIFT) to understand the possible molecule-mineral interactions, and irradiated with a Newport Xenon enhanced UV lamp to evaluate the stability of the organics when adsorbed on magnesium sulfate. The results obtained suggest a photoprotective behavior of magnesium sulfate, which favors organics preservation under UV irradiation, and corroborate the hypothesis that the intriguing signals detected by SHERLOC in association with sulfates could potentially arise from organic compounds.

Acknowledgments: This research was supported by the Italian Space Agency (ASI) through the ASI/INAF agreement n. 2023-3-HH, European Union – Next Generation EU through the PRIN MUR 2022 "Experimental and computational analog studies to support identification of organics on Mars by the NASA Mars 2020 Perseverance rover", and INAF Minigrant 2022.

References: [1] Fornaro T. et al. (2018), Life, 8(4), 56. [2] Scheller E. L. et al. (2022), Science, 378(6624), 1105-1110. [3] Sharma S. et al. (2023), Nature, 619(7971), 724-732. [4] Fornaro T. et al. (2020), Frontiers in Astronomy and Space Sciences, 7, 539289.