Seasonal condensates on Mars : experimental study of CO2 ices formation and metamorphism.
The current climate of Mars causes the formation of seasonal consendates on the surface of high-latitude regions during the polar night. This layer sublimates when exposed to sun in spring. Spatial instruments have enabled to study the spatial and temporal evolution and thermodynamic properties of t...
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Other Authors: | , , , , , |
Format: | Doctoral or Postdoctoral Thesis |
Language: | French |
Published: |
HAL CCSD
2013
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Subjects: | |
Online Access: | https://theses.hal.science/tel-01167247 https://theses.hal.science/tel-01167247/document https://theses.hal.science/tel-01167247/file/pdf2star-1396534150-39116_GRISOLLE_2013_archivage.pdf |
Summary: | The current climate of Mars causes the formation of seasonal consendates on the surface of high-latitude regions during the polar night. This layer sublimates when exposed to sun in spring. Spatial instruments have enabled to study the spatial and temporal evolution and thermodynamic properties of ther CO2-mainly deposits. The aim of this thesis is to supplement this research by laboratory experimentation in order to improve the knowledge of the condensates properties and microphysical process. An experimental set-up, CARBON-IR, has been conceived to manipulate analogous ices in controlled environment. The experiments on CO2, at equilibrium or nonequilibrium, create various grainsize (from about ten microns to several millimeters) and porosity (from 0 to 50% approximately) condensates. The corresponding near-infrared reflectance spectra show specific differences. Compact CO2 slab ices, transluscent or with highly transparency, can be formed by thermal metamorphism of porous snow or by direct condensation of gas. Thermal fluxes balance in the system highlights heat fluxes supplied by the set-up to the sample and the sublimation-condensation process ocurring in it, with matter and energy transfers through the porosity. Thermal and pressure constraints on the ice samples enable to determine the evolution according to of specific parameters, and therefore to comprehend the seasonal condensates microphysic evolution associated with local thermal conditions on Mars polar regions. Accuracy of radiative transfer models and GCM, as well as interpretation of Martian monitoring data will be improved by the confrontation with the experimental results. Le cycle climatique actuel de Mars entraîne la formation d'une couche de condensats saisonniers à la surface des régions de hautes latitudes pendant la nuit polaire elle sublime au printemps avec le retour de l'insolation. Les instruments spatiaux ont fourni de nombreuses informations sur l'évolution spatio-temporelle et les propriétés thermodynamiques de ces dépôts, ... |
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