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Etude en laboratoire de grains extraterrestres et de leurs analogues de synthèse

Abstract : Laboratory analyses performed on extraterrestrial materials originating from primitive bodies of our Solar System, that are bodies known to have suffered low alteration since their formation 4.6 billion years ago, can improve our knowledge on processes that have occurred in the early phase of our planetary system. Furthermore, laboratory simulations of some processes that these materials are likely to suffer during their life cycle also bring precious indications for interpreting observational data as well as for understanding the evolution of solids from the Interstellar Medium to their incorporation into planetary bodies, these latter including asteroids, comets and all kinds of dust that may be observed and/or collected back to Earth.During this thesis, the analysis of silicate as well as organic materials, which have not been much studied jointly so far, in stratospheric particles of cosmic origin, reveals a correlation between the mineralogy of the grains and the lengths of the chains of their carbonaceous component. This link does not seem to be due to parent body processing but rather to trace pre-accretionnal processes. The preservation of pristine components in extraterrestrial materials slightly altered on their parent bodies is again confirmed by the discovery in this work, of inclusions in the “Paris” carbonaceous chondrite whose infrared spectra are similar to the interstellar carbonaceous species. The study of cometary grains from the Stardust space mission showed, unlike the common idea that comets should be composed only of primitive materials since they reside in a cold reservoir, that comets do also contain a number of materials formed at high temperature, thus confirming results from previous studies of Stardust samples and implying large-scale radial mixing of materials in the young Solar system disk.The second part of my work, dedicated to experiments on primitive extraterrestrial amorphous silicates analogs, is aimed to study the role that materials from which Earth has accreted could have played in its water budget in the frame of the “wet accretion” scenario. The experiments performed along this thesis simulating interactions between silicates and water vapor, showed that silicates allow the storage of large quantities of water by adsorption onto their surface of molecules directly from the gas phase.
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Sihane Merouane. Etude en laboratoire de grains extraterrestres et de leurs analogues de synthèse. Autre [cond-mat.other]. Université Paris Sud - Paris XI, 2013. Français. ⟨NNT : 2013PA112229⟩. ⟨tel-00925675⟩



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