Abstract: An international team of scientists including astronomers from the European Space Agency (ESTEC, Netherlands), MIT (Cambridge, USA) and the Paris Observatory (LESIA) has discovered that meteorites differ in composition from near-Earth asteroids.
They explored the mineralogical composition of near-Earth asteroids (NEAs) and their most closely intersecting subset (potentially hazardous asteroids, PHAs) via visible and near-infrared spectroscopy. A priori these km-sized asteroids should have similar compositional distributions to meteorites delivered by more frequent (and less dangerous) smaller impacts. Surprisingly, they do not. Nearly 2/3 of the km-sized Earth-crossing asteroids match a single meteorite class (LL chondrites) that comprises only 8% of all falls. The rather specific spectral signature of NEA's allows them to trace their origin to a specific source at the inner edge of the asteroid belt (Flora family). The much broader compositional distribution of smaller meter-sized bodies (sampled as meteorites) implies a broader range of source regions (likely throughout the asteroid belt). One possible explanation is the role of a size dependent process, such as the Yarkovsky effect, in transporting material from the main belt.