Crumbs from the Crust of Vesta: Achondritic Micrometeorites from the South Pole Water Well (original) (raw)

Introduction: Appreciable numbers of micrometeorites (MM) may form when larger (>1 cm) bodies fragment in the Earth’s atmosphere [1]. If fragmentation affects all incoming bodies similarly, then MM collections should resemble meteorite collections. Compositional and isotopic data support this inference in the broad sense that most MM appear to be “chondritic” [2-5]. Relative to conventional meteorites, however, micrometeorites comprise a larger fraction of carbonaceous material [3,5,6], few or no irons [7], and, to date, no achondrites. Several factors probably account for these differences. First, some MM may arrive as small bodies dust rather than as parts of larger bodies. The principal sources for dust are not necessarily the same as those for conventional meteoroids [8]. Second, the varying toughness of meteoroids and asteroids may influence their susceptibility to break-up. Third, our ability to search for achondritic MM is limited absolutely by the relatively small numbers...