Neutron spectroscopy is used to determine bulk water abundances in the near surface of planetary bodies. The Dynamic Albedo of Neutrons (DAN) instrument on the Mars Science Laboratory (MSL) rover, Curiosity, is able to determine the depth distribution of water and neutron absorbers in the top ~50 cm of the subsurface. In this dissertation, I focus on answering significant geologic questions by interpreting DAN results in the geologic context provided by other MSL and orbital datasets. This approach enabled me to investigate significant outstanding questions in Gale crater geology, with implications for the evolution and habitability of Mars.I mapped an extensive silicic volcaniclastic layer in the subsurface, the first identified and mapped on Mars. This layer served as a silica source for other silica-rich features. But unlike those features, this layer contains abundant rhyolitic glass, indicating an evolved volcanic origin. Similar material on Earth is produced by plate tectonics, so this layer has important implications for the evolution of Mars, which has no evidence of plate tectonics. One of the primary motivations for exploring Gale crater is a distinct clay mineral signature from orbital data of the Compact Reconnaissance Imaging Spectrometer at Mars (CRISM), which has also identified a corresponding hydration signature. I compared DAN and CRISM hydration results and found that CRISM hydration results are biased by the presence of regolith, indicating that this regolith is either more hydrated or has a different grain size texture than bedrock. Clay minerals are primary binding sites for organics on Earth, and most organic-mineral binding mechanisms involve either water or hydroxyl. This makes hydrated clays the most efficient hosts for organic preservation, but clays are normally dehydrated when measured by MSL. However, my DAN-derived water abundances are greater in the most clay-rich unit of Gale crater, suggesting that clay minerals may be hydrated in the subsurface. I developed a new amorphous component analysis method that simultaneously constrains clay mineral hydration and abundances of various hydrated amorphous phases. I found a strong correlation between “excess” water and smectites (expandable clay minerals), indicating that these clay minerals are hydrated in the subsurface.

Fourier Transform Infrared (FTIR) Spectrometers are used to determine surface composition of celestial bodies such as asteroids or planets by collection of infrared spectral data. However, degraded performance for shorter wavelengths may exist when the target does not fill the field of view and may be off-axis. Further study of the optical implications of such use cases would inform future design. This research project aims to develop a systematic method of rapid prototyping in order to progressively simulate optical conditions to characterize the off-axis implications in FTIR spectrometers regarding effects on spectral data measured. With such findings, FTIR spectrometers may be developed to effectively accommodate a larger field of view beyond the current state-of-the-art without increasing the corresponding package size of aft optics such as interferometer assemblies. Throughput may be further increased than current limitations or smaller aft optics systems may be designed with the same throughput. Specific use cases which would otherwise result in degradation of spectral data could potentially be accommodated, all effectively increasing capability of the current technology. With this intent, a preliminary test setup has been developed and initial results were collected.

Emission Spectroscopy is a powerful tool for the identification of mineralogical samples and has been used for decades in labs to study the geology of Earth and Mars. However, the instruments needed to make these measurements are large, expensive and sensitive pieces of equipment that are too cumbersome to use in the field. There are some commercial products that attempt to work in the field, however they perform this task poorly, often resulting in limited applications, poor performance or not being truly portable. My thesis utilizes the TES family of planetary instruments as a source of inspiration for creating a truly portable Fourier Transform InfraRed spectrometer. From this initial design phase, it appears that it is possible to build an instrument with vastly improved capabilities over the current systems on the market. This roughly 12 inch by 7 inch by 8 inch device with a 3-inch diameter telescope is capable of achieving a SNR of over 1000 during a 5 minute scan of a sample allowing for 5 sigma (99.99994% Confidence) identification of 1% spectral features from 5 um to >60 um making this instrument a one of a kind device with high application potential, not only for field geologist but for the future of manned exploration of space. Currently an accurate measurement of costs is not available, however with more development and optimization a total cost of around $50K is feasible while still maintaining the same performance characteristics. If the costs can fall within an acceptable range, this device will not only be technically impressible but viable from a financial standpoint as well.