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Communication Dans Un Congrès Année : 2023

The Organics of Mars

Amy J. Williams
Jennifer L. Eigenbrode
  • Fonction : Auteur
  • PersonId : 1032992
Maëva Millan
Christopher H. House
Roger E. Summons
  • Fonction : Auteur
  • PersonId : 921586
Cyril Szopa
Benjamin Weiss
  • Fonction : Auteur
  • PersonId : 770313
  • IdRef : 192536710
Anastasia Yanchilina
  • Fonction : Auteur

Résumé

Our understanding of organic matter on Mars has evolved from presumed ‘missing organic molecules’ based on Viking data to a robust library of organic molecules detected over the last decade by the SAM (Sample Analysis at Mars) instrument suite onboard the Mars Science Laboratory (MSL) rover, as well as from studies of Mars meteorites. Additionally, recent findings by the Perseverance rover suggest the possibility of simple organics in data from the SHERLOC (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals) fluorescence and Raman spectrometer. Here, we explore the current state of knowledge of organics on Mars from the perspective of in situ characterization with landed instruments, and the potential for new leaps in that knowledge with Mars Sample Return. MSL detections of organics in Gale crater mudstone and sandstones include chlorohydrocarbons up to 300 ppbw; small aliphatic, aromatic, and, sulfur-containing compounds (at 0.1-10 ppmw detections) potentially originating from macromolecular organics and long-chain alkanes from C10 to C12. Total abundance of C is likely higher than individual molecular detections and on the order of 100’s of ppmw. The recent TMAH wet chemistry experiment liberated macromolecular organics, resulting in the detection of one to two-ring aromatic compounds, benzoic acid methyl ester, and benzothiophene. All these detections confirmed the presence of organics in the Martian subsurface, despite exposure to ionizing radiation for at least 80 My. More recent findings from the SHERLOC instrument onboard the Mars2020 rover include fluorescence and Raman spectra that may be consistent with one- and two-ring organic molecules, although other inorganic sources for the spectra are possible. The next-generation instruments onboard the ExoMars rover (Raman, MicrOmega spectrometer and MOMA chemical analyzer), combined with a 2-meter drill, will enable investigation of better protected subsurface samples. The two current in situ organics detection techniques are quite different, but Mars Sample Return in the mid-2030s would provide the first groundtruth of these data, enable the search for other organic molecules that are not detectable by in situ instrumentation, and address fundamental outstanding questions about the origin of organics on Mars.
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Dates et versions

insu-04385218 , version 1 (10-01-2024)

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  • HAL Id : insu-04385218 , version 1

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Amy J. Williams, Jennifer L. Eigenbrode, Maëva Millan, Jennifer C. Stern, Caroline Freissinet, et al.. The Organics of Mars. AGU Fall Meeting 2023, Dec 2023, San Francisco, United States. ⟨insu-04385218⟩
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