Physico-chemical properties of chondritic meteoritesclues on the origin and evolution of their parent bodies /

Abstract

In the first million years of the solar nebula, specific conditions triggered, from aggregation and melting of dust and presolar grains, the formation of the first solid materials of the Solar System. Among them, a variety of igneous glassy spherules known as chondrules can be found. These materials progressively aggregated together with dust and interplanetary particles to form larger bodies, such as asteroids, planetesimals, and finally planets. From those, some experienced chemical segregation due to heating and melting of their materials. The bodies that did not melt, called undifferentiated, still conserve some of these very primordial materials of the Solar System. The meteorites coming from these objects, known as chondrites from the chondrules that they contain, are therefore samples of materials formed in the protoplanetary disk around the Sun about 4,600 million years ago. This thesis studies chondrites with a multidisciplinary approach, starting with the exploration of several instrumental techniques applied to a Martian meteorite. Those techniques allow the study of several physico-chemical properties of chondrites, and therefore provide clues about the complex accretionary histories of their parent bodies. The specific mineralogy and features related to thermal metamorphism, aqueous alteration, and the effects of shock of two chondrites are described here in the context of their possible parent asteroids. Besides, spectroscopic techniques are applied as suitable method to link the meteorite samples to specific asteroids currently populating the Solar System. Retrieving samples directly from asteroids is a very complex concept, and therefore terrestrial collections of meteorites become a very available source of samples. The information obtained from chondrites can be extrapolated to better understand the composition, structure, and physical properties of asteroids. Thus, the study of chondrites can facilitate the practical applications on asteroids, such as space mining or the concept explored in this thesis: the deflection through solid projectiles of asteroids that suppose a potential thread to life on Earth, one of the goals the ESA and NASA collaboration known as the AIDA mission. Most of these potentially dangerous objects are made of chondritic materials, and therefore the study of chondrites can provide valuable information about them, which is key in order to be prepared for the possible future catastrophic impact events.