Analyzing geological materials under Martian conditions using laser-induced breakdown spectroscopy: Plasma fundamentals, sample classification, and trace element quantification

Laser-induced breakdown spectroscopy (LIBS) is an emission spectroscopy analysis technique that continues to be developed for the study of solids, liquids and gases. Geological applications for LIBS are a particularly exciting area of research, in part due to the capabilities of the technique to quickly and simultaneously detect nearly all major, minor and trace elements on unprepared samples either in a laboratory setting or in situ. A significant advancement in LIBS research is the recent deployment of ChemCam to the surface of Mars at Gale crater onboard the Mars Science Laboratory (MSL) rover, Curiosity. ChemCam consists of a LIBS instrument and a high resolution micro-imager (RMI) and is the first extraterrestrial application for LIBS. While the state of LIBS research is rapidly developing, there are still many aspects of the techniques that warrant additional study. In this work, I have primarily focused on avenues of investigation that are most applicable to ChemCam. To encompass the range of LIBS research and applications with respect to geological materials, I have compiled a body of work that explores aspects of the fundamentals of LIBS plasma temperature as a function of distance, sample classification based on a spectral matching technique called Partial Least Square-Discriminant Analysis, and the quantification of several trace elements (Li, Rb, Sr, and Rb) using ChemCam spectra. Trace element abundances and implications for geological processes on Mars for the first 100 sols of martian rocks and soils analyzed by ChemCam are also discussed.