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Poster De Conférence Année : 2023

Secondary X-ray influence on the transformation of organic molecules on Mars and determination of by-products from Early-Mars/Earth compounds

A. Buch
Joyce Mcbeth
  • Fonction : Auteur
Caroline Freissinet

Résumé

Introduction The Sample Analysis at Mars (SAM) instrument onboard NASA Curiosity rover revealed organic matter indigenous to a Martian sample with the detection of chlorohydrocarbons [1]. These molecules are thought to originate from a reaction of unidentified higher molecular mass organic matter with Martian perchlorates. The reaction may occur at Mars’ near-surface induced by the harsh radiative environment, e.g. direct radiation (UV, high energy X- and γ-rays) and secondary photons produced by the interaction of direct radiations with the martian regolith (low energy secondary X-rays).  To address the influence of high energy X-rays directly reaching Mars surface on the degradation of organic molecules, a synchrotron session was undertaken on the PSICHE beam line. The reactivity and chemical characterization of L-alanine and benzoic acid exposed to hard X-rays (25-50 keV) did not show any degradation of organics nor formation of chlorohydrocarbons. In conclusion, the X-rays of the PSICHE beam line may have been too energetic for degrading efficiently organic molecules [3, 4]. This why we have investigate the impact of soft X-ray irradiation on the SXRMB and BioXAS beamlines at CLS at the 2.6 and 6.4 keV energy which is the energy range for the majority of secondary emissions and monitoring the evolution of perchlorate Cl by X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). X-rays do not modify the chirality of the organic molecules, which represent a biosignature we search.
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Dates et versions

hal-04462958 , version 1 (20-02-2024)

Identifiants

  • HAL Id : hal-04462958 , version 1

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David Boulesteix, A. Buch, Joyce Mcbeth, Caroline Freissinet, Cyril Szopa. Secondary X-ray influence on the transformation of organic molecules on Mars and determination of by-products from Early-Mars/Earth compounds. CLS conference, Aug 2023, Saskatoon, SK, Canada. ⟨hal-04462958⟩
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