Laboratory Heating of HED + CC Mixtures Indicates Localized Oxidation on Vesta

Kurzfassung

On asteroid Vesta, pyroxenedominated materials prevail (i.e., HED meteorite-like material; e.g., [1-3]) and since NASA’s Dawn mission it has been known that a dark component – likely OHbearing carbonaceous chondrite (CC) material – reduces the spectral characteristics of the Vestan regolith (e.g., [4-6]). Pitted impact deposits on Vesta have been shown to exhibit distinct spectral characteristics [7]: higher reflectance and pyroxene band strength with respect to their immediate surroundings. These immediate surroundings are likely deposits with same ages and initial composition [7], thus the origin of spectral differences is still unclear and inconsistent with variations in grain size, roughness, shock or glass content. These pitted impact deposits indicate rapid devolatilization of the host material ([7-9]). The driver of this devolatilization is likely impact heat and here we present heating experiments of HED + CC material in order to elucidate what could cause the distinct spectral characteristics of the pitted impact deposits.