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Classification de la surface de Mars par imagerie hyperspectrale OMEGA. Suivi spatio-temporel et étude des dépôts saisonniers de CO2 et H2O.

Abstract : Imaging spectrometer, the last generation of space instruments, strongly modify the study of planetary surfaces. Those detectors record manifold hyperspectral images (an image for which each pixel is associated with a spectrum). Such instrument allows us to follow the soil optical properties through space and time. The first objective of my thesis is to propose some tools to analyse a huge amount of images and spectra in planetological perspectives. Two types of methods are introduced to examine the data acquired by the OMEGA instrument (Mars Express/ESA) : (i) WAVANGLET, a fast detection algorithm to identify the presence of chemical species at the ground, (ii) JADE+BPSS, a blind source separation method that is able to detect chemical species without a priori.
The Martian annual cycle of CO2 consist of an exchange between surface and atmosphere, which is particularly relevant in Polar Regions. During the polar night, atmospherical CO2 condensate at the ground, whereas it starts to sublimate again during the spring, when the solar light heat up the surface. This major climatic cycle has been revealed in the 1960th but even today, the microphysic of interaction between surface and atmosphere is still unknown. The second objective of this thesis is to build a model of the seasonal deposit sublimation. The mass balance is simulated by a radiative balance on a rough surface. The confrontation of this model with various dataset shows that the seasonal south polar cap sublimation is mainly controlled by its albedo. Further studies must determine the exact mechanisms in the origin of this albedo variability (metamorphism, dust contamination,. . . ).
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Contributor : Schmidt Frédéric <>
Submitted on : Monday, April 7, 2008 - 10:22:44 AM
Last modification on : Friday, November 6, 2020 - 4:01:25 AM
Long-term archiving on: : Tuesday, September 21, 2010 - 3:51:35 PM

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  • HAL Id : tel-00192298, version 2

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Schmidt Frédéric. Classification de la surface de Mars par imagerie hyperspectrale OMEGA. Suivi spatio-temporel et étude des dépôts saisonniers de CO2 et H2O.. Astrophysique [astro-ph]. Université Joseph-Fourier - Grenoble I, 2007. Français. ⟨tel-00192298v2⟩

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