Research Themes

Remote Sensing & Geologic Mapping of Mars

Research in our group focuses on integrating lab, theory, field, and remote observations to achieve a better understanding of the formation and evolution of planetary surfaces.

Several current areas of study are outlined below, but overarching themes include understanding the role of water in the Solar System, using visible-near infrared spectroscopy for quantitative mapping of surface compositions, and assessing the formation and stability of hydrous minerals under various conditions.

The past ten years have been truly revolutionary in our understanding of the Red Planet. One of the fascinating things about Mars is that its rocks have recorded processes very similar to those that occur on Earth, yet at the same time Mars has clearly followed a very different evolutionary trajectory. In a broad sense, this research theme is focused on understanding the lateral and vertical distribution of hydrous minerals on Mars, the relationships between morphology and mineralogy, and the timing, duration, and fate of water on Mars. This is accomplished by integrating numerous datasets acquired for Mars by satellites, rovers, and landers with theory and basic geologic principles, using our knowledge of geologic processes on Earth as our guide. The goal is to unravel the geologic and climatic evolution of Mars by increasing our knowledge of the modern and ancient rock record, with an emphasis on sedimentology, stratigraphy, and water-related processes.

Water on the Lunar Surface

The presence of ‘water’, meaning either OH or H2O, has been confirmed in lunar glasses as well as on the lunar surface. The hydrous nature of the volcanic glasses indicates that the interior of the Moon contains water, whereas the presence of ‘water’ on the surface may be caused by solar-wind interaction with the regolith. The presence of H+ and apparently water ice in permanently shadowed craters may reflect the migration and trapping of such volatiles or may have a cometary origin. Our research group is currently attempting to map and quantify the lunar surface ‘water’ using hyperspectral imaging data acquired by the Moon Mineralogy Mapper, relying on methods we developed in the laboratory and have previously applied to Mars data. In addition, this project seeks to understand the effects of radiation on lunar-like materials to understand the processes and role of solar wind in surface-OH formation. This is accomplished through laboratory experiments that will help to understand and quantify rates and amounts of OH/H2O production on the lunar surface.

Remote Sensing of Carbonates in West Texas & New Mexico

The Guadalupe Mountains in New Mexico and West Texas are an ideal location to test the ability of remote sensing techniques to identify transitions in ancient marine and carbonate reef environments. This project integrates lab, field, and remote observations to determine if remote sensing data (AVIRIS hyperspectral data) can be used to accurately identify the transitions from backreef/evaporitive to shallow water/shelf to deep water/basinal facies in a carbonate reef system. Another goal of this project is to determine how surface and textural effects of natural rocks and outcrops affects their spectral signatures in field, lab, and remote reflectance data and how such factors affect derived mineral abundances when applying models derived for particulate samples to real-world geologic scenarios.

Visible-Near Infrared Reflectance Spectroscopy of Clay Minerals

Clay minerals are abundant on Earth and are becoming an ever more important part of understanding the role of water and potential for life on Mars. In addition, nearly all sediments on Earth experience some form of diagenesis due to burial and crustal recycling by plate tectonics. This is in marked contrast to clays that have been found on Mars, which are suggested to be several billion years older than the oldest clays on Earth. Thus, comparing the composition and determining the history of clays on these two planets can provide a natural test of the long-term stability of clay minerals and the rates and role of diagenetic processes in the alteration of clays. Visible-near infrared reflectance spectroscopy provides a rapid way to identify the presence of clays in many rocks and soils, and this research theme focuses on how to use this technique in a quick, reliable way to determine the composition, chemistry, and thermal history of clays and associated phases.

Quantitative Mineralogy Using Reflectance Spectroscopy

A major theme in our research group is to understand the extent to which reflectance spectroscopy can be used as a quantitative technique to map the composition and thus geology of planetary surfaces. Our current understanding of planetary bodies comes largely from remotely sensed data acquired by satellites, rovers, and landers. In addition, satellite and airborne sensors also provide valuable information on how the surface of Earth is changing on daily, yearly, and decadal timescales. By integrating theory with laboratory, field, and remote observations we seek to understand the scattering and reflectance properties of outcrops, rocks, and particulate/soil samples at a variety of spatial scales to assess how remote techniques at visible to mid-infrared wavelengths can be used to determine the modal mineralogy of samples and, ultimately, used to create reliable geologic maps.

A current part of this research theme is in conjunction with colleagues at Arizona State University and focuses on understanding the visible, near-infrared, and thermal spectral properties of opaline (silica) deposits formed in a variety of environments. These environments include hot springs in Yellowstone National Park and volcanic fumaroles in Hawaii. The goal is to determine if different types of opaline silica and associated minerals have unique chemical or spectral signatures that reflect their formation environment. Such information could then prove useful in determining whether opaline deposits that have been found on Mars indicate low or high temperature conditions, acidic or alkaline fluids, and the implications of those deposits for habitability and preservation of organic material on Mars.

The Curiosity Rover and Geology of Gale Crater

NASA’s Mars Science Laboratory rover, Curiosity, is currently exploring the geology of Gale Crater and the ~5 km tall Mt. Sharp. This project focuses on examining available images and hyperspectral reflectance data acquired by instruments on various Mars satellites, most notably the CTX, HiRISE and CRISM instruments on the Mars Reconnaissance Orbiter, to determine the mineralogy and geologic history of Gale Crater and Mt. Sharp. These data are then integrated with ongoing rover observations in order to assess the geology along the traverse route to Mt. Sharp, providing a clearer picture of the stratigraphic relationships and distribution of hydrous minerals within Gale Crater. Results from rover observations are then used to design laboratory experiments to examine the spectral properties of minerals and rocks that are relevant to Gale under Mars-like conditions, allowing for a better comparison to orbital data.