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L'hydratation de la surface de Mars vue par l'imageur spectral OMEGA

Abstract : Water is currently present on Mars as ice, vapor and surface hydration. Hydration is known to be adsorbed water on minerals or prisoned in their structure. It can influence the Martian water cycle as well as enable mineral alteration or exobiology. This PhD thesis studies the global and seasonal aspects of hydration using the data from the visible and near infrared imaging spectrometer OMEGA. Our work is based on the 3 µm hydration absorption feature, which has required to develop an efficient scheme to get the albedo spectra in the OMEGA long wavelength channel (L channel). We had in particular to assess the surface thermal emission from the spectra. The L channel photometric efficiency undergoes strong variations with time; we have therefore derived an adapted new calibration using an innovating method to get a representative spatial and seasonal coverage. Our study reveals that hydration is everywhere on Mars with water contents between 3 and 7 weight %, which is evidence of overall adsorbed water as well as global alteration. The hydration dependency with temperature and pressure is consistent with laboratory measurements, and composition may influence the water bond strength. Brightest surfaces are likely to be more hydrated. The influence on the water cycle is proved by the observation of seasonal variations as well as an increase over icy sub-surfaces. Finally, carbonates are expected as an alteration product in hydrated surfaces, but our systematic research on the 3.4 µm proves their missing in large amounts on Mars. This result also puts constrains on atmospheric history scenarios.
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Contributor : Denis Jouglet <>
Submitted on : Wednesday, May 13, 2009 - 10:34:57 PM
Last modification on : Wednesday, October 14, 2020 - 3:42:33 AM
Long-term archiving on: : Thursday, June 10, 2010 - 11:07:57 PM

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  • HAL Id : tel-00383967, version 1

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Denis Jouglet. L'hydratation de la surface de Mars vue par l'imageur spectral OMEGA. Physique [physics]. Université Paris Sud - Paris XI, 2008. Français. ⟨tel-00383967⟩

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