ORCID
http://orcid.org/0000-0003-4646-2852
Date of Award
Spring 5-15-2023
Degree Name
Doctor of Philosophy (PhD)
Degree Type
Dissertation
Abstract
Spectroscopic imagers have been used to analyze the surface of Mars at varying spatial scales in several distinct modalities, each of which provides different information about surface geology and geochemistry. In this dissertation, we take a closer look at two such spectroscopic imagers: the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on board the Mars Reconnaissance Orbiter and the Planetary Instrument for X-ray Lithochemistry (PIXL) on board the Mars 2020 rover Perseverance. We apply new mathematical models to data collected by CRISM to infer physical properties from a complex (and therefore underutilized) portion of the spectrum, and to data collected by both instruments to put quantitative confidence bounds on detections of subtle features.In Chapter 2, we develop a method to retrieve apparent thermal inertia estimates from thermal data separated out from the longer wavelength portion of the CRISM spectra, producing the highest-resolution orbital thermal inertia dataset available from Mars. This method is validated against other orbital and landed thermal data sets, and is used to characterize surface properties in and around the Glen Torridon region in Gale Crater, field site of the Mars Science Laboratory rover Curiosity. These properties include local variations in sand grain size in basaltic sand fields, spatial variations in rock fragment abundance on the Vera Rubin ridge, and the identification of a thin layer of wind-blown sand on top of the Greenheugh pediment. In Chapters 3 and 4, we analyze the statistical properties of noise in both PIXL (Chapter 3) and CRISM (Chapter 4) data sets to characterize each instrument’s capability to detect subtle features. Chapter 3 examines trace element signals in PIXL X-ray fluorescence spectra to determine the minimum concentration of each trace element that can be detected in a specific PIXL scan. This is then extended to estimate the required scan parameters for a PIXL observation capable of detecting a trace element at some predetermined concentration, as a guideline for future PIXL observation planning. Chapter 4 analyzes spectral absorption features in CRISM data associated with rare mineral phases (those which are present only in a small number of pixels in a CRISM scene) to estimate the degree of confidence in detections of those mineral phases. These techniques are applied to the detection of hydrated silica in Jezero Crater, field site of Perseverance, both to validate the approach used and to search for any previously undetected exposures of hydrated silica in the area. Two new hydrated silica detections have been identified, which, when combined with high-resolution apparent thermal inertia estimates retrieved using the methods of Chapter 2, provide additional constraints on the formation mechanism of hydrated silica within the western Jezero delta.
Language
English (en)
Chair and Committee
Raymond E. Arvidson
Committee Members
Jeffrey G. Catalano, Joseph A. O'Sullivan, Scott J. VanBommel, Douglas A. Wiens,
Recommended Citation
Christian, John Randall, "Application of Advanced Mathematical Approaches to the Interpretation of Remote Sensing Observations of the Surface of Mars" (2023). Arts & Sciences Electronic Theses and Dissertations. 2844.
https://openscholarship.wustl.edu/art_sci_etds/2844