Influence des phases amorphes dans la réponse optique des régolites planétaires : caractérisation des propriétés physiques et application à l'étude géologique de la Lune

Abstract : Remote-sensing techniques are widely implemented today for the exploration of planetary surfaces, called regoliths, such as the Moon's, Mercury's, Mars' or asteroids'. Photometry is a technique based on the observation of a surface under various angles which gives information on the physical surface properties: particles' diffusion mode (forward-scattering or backscattering), grain size, surface roughness, compaction state... This PhD is centred on volcanic materials and amorphous phases (or glasses), because of their significance in processes leading to the formation and evolution of regoliths: volcanism, cratering, interaction with space environment. Using Hapke's photometric model, whose parameters, once inverted, lead to the physical surface properties, this subject is explored under two approaches: in laboratory, and from orbital data. Multiangular experimental measurements, carried out with IRAP's spectro-imaging device, allowed the photometric characterization of different natural granular volcanic materials with various compositions, grain sizes, and contents of glass and monocrystals: basalts, volcanic sand, pyroclastics, olivine, and glass from the controlled melt of basalt. According to their compositions, shapes, and textures, an evolution of the samples photometric behaviour with grain size has been noticed. Materials which are rich in fresh glass and/or monocrystals display a specific behaviour seldom observed so far, which enable their distinction from glass-free materials or with more mature glass. Mixtures of basalt and basaltic glass showed also the strong and highly non linear optical influence of fresh glass. A photometric study of the lunar crater Lavoisier from orbital data showed the applicability of techniques implemented in laboratory on geological units, and photometric characteristics inherent to the pyroclastic deposits on the crater floor have been determined. Another pyroclastic deposit located at Lavoisier F displays a photometric behaviour distinct from crater Lavoisier's pyroclastic deposits, showing a textural, granulometric or compositional variety between these units. All the results obtained for these craters make sense in the light of laboratory experiments.
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Planetology. Université Paul Sabatier - Toulouse III, 2012. French


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Audrey Souchon. Influence des phases amorphes dans la réponse optique des régolites planétaires : caractérisation des propriétés physiques et application à l'étude géologique de la Lune. Planetology. Université Paul Sabatier - Toulouse III, 2012. French. <tel-00694176>

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