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Title: Understanding the formation and evolution of asteroids through analysis of carbonaceous chondrites
Author: Bates, Helena
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2020
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The transport and evolution of volatiles (e.g. water, organics) during the formation of the inner terrestrial planets of our Solar System is relatively poorly constrained. A number of dynamical mechanisms have been proposed that transport volatile rich material from the outer Solar System (i.e. from beyond the snow-line, currently 5 AU), and primitive, volatile-rich asteroids may provide clues as to these processes. Observations demonstrate that these asteroids have similar infrared spectra to CI, CM and CY carbonaceous chondrite meteorites. Thus, by studying the composition and alteration histories of these families of meteorites it can potentially provide insights into the physical processes that occurred or are occurring on these asteroids. In this thesis I link trends in the spectra of both aqueously altered and aqueously and thermally altered CI, CM and CY chondrites with meteorite mineralogy. I demonstrate how these trends may be applied to remote asteroid spectra to examine their surface mineralogy and processing history. I describe how trends in the near- (NIR) and mid-infrared (MIR) spectra of aqueously altered meteorites can reflect the phyllosilicate composition and therefore degree of aqueous alteration. I also report that trends in aqueously and thermally altered meteorite NIR and MIR spectra reflect a combination of phyllosilicate and olivine compositions and abundances. Furthermore, I describe and assess differences between the MIR reflectance spectra typically collected in laboratories, and emissivity spectra acquired under asteroid environmental conditions that more accurately replicate the spectral flux received when observing a remote airless body. I then use the spectra collected to aid in the interpretation of spectra of a range of potentially volatile-rich objects including NEOs visited by Hayabusa2 and OSIRIS-REx, main-belt asteroids and Jupiter Trojans. The spectra will also be a valuable aid in analysis of future remote telescopic observations of and spacecraft missions to small bodies.
Supervisor: Donaldson Hanna, Kerri ; Russell, Sara ; Bowles, Neil ; King, Ashley Sponsor: Science and Technology Facilities Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Asteroids ; Carbonaceous chondrites (Meteorites) ; Reflectance spectroscopy ; Thermal emission spectroscopy