Asteroid-Meteorite Linkages through Infrared Spectroscopy

Abstract

Asteroids are cosmic puzzles. Meteorites can serve as puzzle pieces to help construct geochemical context of the Solar System and are also pieces derived from asteroids. Ordinary chondrites are the most common types of meteorites that arrive to Earth and are composed of three subtypes: H, L and LL chondrites. Meteorites that have undergone complex melting and geological changes, named the achondrites, provide clues towards the foundation and patterns of planetary formation. Understanding both ordinary chondrite and achondrite meteorites creates the criteria in which their parent asteroids must also possess. A result of this work is affirming that asteroid-meteorite linkages can be established through infrared spectroscopy. The Gefion Asteroid Family (GAF) has been proposed to be the source asteroids for the L chondrite meteorites. In this thesis results are presented for 18 dynamically defined members of the GAF through a near-infrared (0.7-2.5 micrometers (µm)) spectroscopic survey. These results are presented to test the hypothesis that L-chondrites originate from this family (McGraw et al. 2018, 2022). Compositional analysis of these asteroids shows a range of meteorite analogs for the entire ordinary chondrite range of H-, L-, and LL, and possibly the subcategory of L/LL chondrites. The anomalous achondrite meteorite Northwest Africa (NWA) 6704 has basaltic texture and silicate mineralogy. However, NWA 6704 also shows isotopic consistencies with other carbonaceous chondrite meteorites (McGraw et al. 2020). The spectral data of the achondrite meteorite clan known as the howardites, eucrites, and diogenites (HEDs) are also of basaltic nature and are derived from asteroid (4) Vesta. Problematically, the HEDs and anomalous achondrites share similar spectral absorption features. Thus, searching for the parent asteroid sources for geologically evolved achondrites that may be hidden amongst the V-type asteroid population is an important goal within planetary science. A portion of this thesis work investigates multiwavelength spectroscopy (0.35-25 µm) in order to determine spectral diagnostic features and differences from other achondrite meteorites such as the HEDs.