Meteorite-dropping bodies from cometary meteoroid streams and their physical properties

Abstract

Until recently it was considered that the sources of meteorite-dropping bodies are asteroidal fragments mostly delivered by main belt resonances crossing the Earth’s orbit. Such source may include a considerable fraction of meteorites falling at a given time [1]. Wetherill initially discarded comets as a probable source of meteorites [2], but recent results seem to indicate that they could also contribute [3, 4]. The terrestrial collections of meteorites include the ordinary chondrites meteorites represented by ~85% of meteorite falls and finds, but only ~40% of the total meteorite mass. Iron meteorites account for 50% of the mass but only ~4% of meteorites. Carbonaceous chondrite meteorites forming ~9% of the mass are underrepresented due to their fragility and low density [5]. It has been estimated that ~24,000 meteorites with masses from 100 g to 10 kg fall to the Earth each year and amongst them a few ones might have a cometary provenance. Some Near Earth Objects (NEOs) supports the notion that dormant nuclei of periodic comets can have asteroidal appearance, and that some fraction of the NEOs have a cometary origin and are potentially delivering meteorites to the Earth.