Collected extraterrestrial materials: Constraints on meteor and fireball compositions

The bulk density and bulk porosity of IDPs and various meteorite classes sh ow that protoplanet accretion and evolution were arrested at different stag es as a function of parent body modification. The collected IDPs, micromete orites and meteorites are aggregates of different structural entities that were inherited from the earliest times of solar system evolution. These str uctural entities and the extent of parent body lithification will determine the material strength of the meteoroids entering the Earth's atmosphere. T here is a need for measurements of the material strength of collected extra terrestrial materials because they will in part determine the nature of the chemical interactions of descending meteors and fireballs in the atmospher e. High-precision determinations of meteor and fireball compositions are re quired to search for anhydrous, carbon-rich proto-CI material that has surv ived in the boulders of comet nuclei.