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Étude des signatures aqueuses martiennes par spectroscopie infrarouge : des nuages à l'altération des régions polaires

Aurélien Stcherbinine 1, 2
1 PLANETO - LATMOS
LATMOS - Laboratoire Atmosphères, Milieux, Observations Spatiales
Abstract : On Mars, the major infrared signature of the surface consists of a broad absorption band at 3 µm. It is mainly associated with the presence of H2O molecules or –OH groups and provides insight about the presence of water ice and the hydration level of soils. It is observed both at the surface and in the atmosphere which contains clouds and dust. In this thesis, we use the 15 years dataset of the Observatoire pour la Minéralogie, l’Eau, les Glaces et l’Activité (OMEGA), as well as new measurements provided since spring 2018 by the Atmospheric Chemistry Suite (ACS) onboard the Trace Gas Orbiter (TGO) to study this 3 µm signature.The OMEGA/Mars Express imaging spectrometer reached Mars in 2004 to map the entire surface of the planet between 0.35 and 5.1 µm. This allowed the identification and characterization of ice and minerals, and also the determination of the soil hydration level as derived from the depth of the 3 µm band. In the polar regions, OMEGA revealed a significant increase of surface hydration, but the nature of this hydration is still debated. From the analysis of the evolution of the 3 µm band in the OMEGA data, we were able to highlight the presence of a new narrow signature centered on 3 µm, specific to the north polar regions and distributed along a ring-shaped structure around the perennial north polar cap. This spectral feature could be related to sulfates and may indicate the action of a relatively recent soil alteration phenomenon in the northern high latitudes, potentially involving water ice.Concurrently, ACS solar occultation observations allowed us to use the 3 µm atmospheric band to detect and characterize the Martian water ice clouds, as well as their spatial and temporal evolution over a Martian year. In particular, we were able for the first time to precisely study the impact of a Martian planetary dust storm on atmospheric water ice particles, and to highlight the presence of large-grained clouds at altitudes that have never been observed before.
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Submitted on : Friday, October 15, 2021 - 12:25:23 PM
Last modification on : Tuesday, January 4, 2022 - 6:38:53 AM
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  • HAL Id : tel-03380027, version 1

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Aurélien Stcherbinine. Étude des signatures aqueuses martiennes par spectroscopie infrarouge : des nuages à l'altération des régions polaires. Planétologie et astrophysique de la terre [astro-ph.EP]. Université Paris-Saclay, 2021. Français. ⟨NNT : 2021UPASP064⟩. ⟨tel-03380027⟩

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