V-type Asteroids as the Origin of Mesosiderites

Description

We present the results of a campaign of hypervelocity impact experiments on natural mesosiderite targets, using representative main asteroid belt impact speeds. The objective is to document further the surface evolution of iron-rich asteroids. In contrast with iron meteorites, we demonstrate the fragile behavior of mesosiderite at impact since experiments result in both cratering and catastrophic disruption. The behavior of metal-rich asteroids at impact is thus highly influenced by the original ratio of metal/silicate. A visible to near-infrared spectral analysis shows that the pyroxene silicate signature of impacted mesosiderites, or their ejecta, is fully preserved. Our results thus rule out a mesosiderite hypothesis for the very nature of M/X-type asteroids including (16) Psyche, despite a small fraction of its surface possibly being covered by mesosiderite-like materials. Finally, we address the question of whether mesosiderites and howardite–eucrite–diogenite (HED) meteorites are genetically linked to (4) Vesta or other differentiated asteroids in the main belt based on their spectral similarity.

Abstract

International audience

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