Some things special about NEAs : Geometric and environmental effects on the optical signatures of hydration

Séminaire IPAG de Sandra Potin (Doctorante IPAG), jeudi 7 mars 2019 à 11h00, salle Manuel Forestini

Spectral signatures of hydration are detected on a majority of Main-Belt Asteroids (MBAs) corresponding to C-types asteroids, while they seem scarce in the Near-Earth Asteroids (NEAs) population. Two space missions are presently “en route” toward possibly volatile-rich near-Earth asteroids (NEAs) (Hayabusa-2 and Osiris-REX) and the origin of this hydration difference remains to be understood. Signatures of aqueous alteration are also recorded in the optical properties of primitive meteorites, our samples of asteroids.
I will present how the environment of NEAs and the observations themselves can influence the signatures of aqueous alteration. For that purpose, I selected a freshly fallen aqueously altered meteorite, the Mukundpura CM2 chondrite. The effect of observation geometry and the impact of surface texture (comparison of rock and regolith) were investigated using the custom-made reflectance-goniometer SHADOWS, and the impact of thermal processing on the infrared signature was studied in situ using the high-temperature, high-vacuum reflectance cell MIRAGE.