Matching Items (4)
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- All Subjects: Volcanism
- All Subjects: Planetary Science
Description
Lunar Reconnaissance Orbiter (LRO) and MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft missions provide new data for investigating the youngest impact craters on Mercury and the Moon, along with lunar volcanic end-members: ancient silicic and young basaltic volcanism. The LRO Wide Angle Camera (WAC) and Narrow Angle Camera (NAC) in-flight absolute radiometric calibration used ground-based Robotic Lunar Observatory and Hubble Space Telescope data as standards. In-flight radiometric calibration is a small aspect of the entire calibration process but an important improvement upon the pre-flight measurements. Calibrated reflectance data are essential for comparing images from LRO to missions like MESSENGER, thus enabling science through engineering. Relative regolith optical maturation rates on Mercury and the Moon are estimated by comparing young impact crater densities and impact ejecta reflectance, thus empirically testing previous models of faster rates for Mercury relative to the Moon. Regolith maturation due to micrometeorite impacts and solar wind sputtering modies UV-VIS-NIR surface spectra, therefore understanding maturation rates is critical for interpreting remote sensing data from airless bodies. Results determined the regolith optical maturation rate on Mercury is 2 to 4 times faster than on the Moon. The Gruithuisen Domes, three lunar silicic volcanoes, represent relatively rare lunar lithologies possibly similar to rock fragments found in the Apollo sample collection. Lunar nonmare silicic volcanism has implications for lunar magmatic evolution. I estimated a rhyolitic composition using morphologic comparisons of the Gruithuisen Domes, measured from NAC 2-meter-per-pixel digital topographic models (DTMs), with terrestrial silicic dome morphologies and laboratory models of viscoplastic dome growth. Small, morphologically sharp irregular mare patches (IMPs) provide evidence for recent lunar volcanism widely distributed across the nearside lunar maria, which has implications for long-lived nearside magmatism. I identified 75 IMPs (100-5000 meters in dimension) in NAC images and DTMs, and determined stratigraphic relationships between units common to all IMPs. Crater counts give model ages from 18-58 Ma, and morphologic comparisons with young lunar features provided an additional age constraint of <100 Ma. The IMPs formed as low-volume basaltic eruptions significantly later than previous evidence of lunar mare basalt volcanism's end (1-1.2 Ga).
ContributorsBraden, Sarah E (Author) / Robinson, Mark S (Thesis advisor) / Bell, James F. (Committee member) / Christensen, Philip R. (Committee member) / Clarke, Amanda B (Committee member) / Lawrence, Samuel J (Committee member) / Arizona State University (Publisher)
Created2013
Description
On Mars, sedimentary deposits reveal a complex history of water- and wind-related geologic processes. Central mounds – kilometer-scale stacks of sediment located within craters – occur across Mars, but the specific processes responsible for mound formation and subsequent modification are still uncertain. A survey of central mounds within large craters was conducted. Mound locations, mound offsets within their host craters, and relative mound heights were used to address various mound formation hypotheses. The results suggest that mound sediments once filled their host craters and were later eroded into the features observed today. Mounds offsets from the center of their host crater imply that wind caused the erosion of central mounds. An in depth study of a single central mound (Mt. Sharp within Gale crater) was also conducted. Thermal Emission Imaging System Visible Imaging Subsystem (THEMIS-VIS) mosaics in grayscale and false color were used to characterize the morphology and color variations in and around Gale crater. One result of this study is that dunes within Gale crater vary in false color composites from blue to purple, and that these color differences may be due to changes in dust cover, grain size, and/or composition. To further investigate dune fields on Mars, albedo variations at eight dune fields were studied based on the hypothesis that a dune’s ripple migration rate is correlated to its albedo. This study concluded that a dune’s minimum albedo does not have a simple correlation with its ripple migration rate. Instead, dust devils remove dust on slow-moving and immobile dunes, whereas saltating sand caused by strong winds removes dust on faster-moving dunes.
On the Moon, explosive volcanic deposits within Oppenheimer crater that were emplaced ballistically were investigated. Lunar Reconnaissance Orbiter (LRO) Diviner Radiometer mid-infrared data, LRO Camera images, and Chandrayaan-1 orbiter Moon Mineralogy Mapper near-infrared spectra were used to test the hypothesis that the pyroclastic deposits in Oppenheimer crater were emplaced via Vulcanian activity by constraining their composition and mineralogy. The mineralogy and iron-content of the pyroclastic deposits vary significantly (including examples of potentially very high iron compositions), which indicates variability in eruption style. These results suggest that localized lunar pyroclastic deposits may have a more complex origin and mode of emplacement than previously thought.
On the Moon, explosive volcanic deposits within Oppenheimer crater that were emplaced ballistically were investigated. Lunar Reconnaissance Orbiter (LRO) Diviner Radiometer mid-infrared data, LRO Camera images, and Chandrayaan-1 orbiter Moon Mineralogy Mapper near-infrared spectra were used to test the hypothesis that the pyroclastic deposits in Oppenheimer crater were emplaced via Vulcanian activity by constraining their composition and mineralogy. The mineralogy and iron-content of the pyroclastic deposits vary significantly (including examples of potentially very high iron compositions), which indicates variability in eruption style. These results suggest that localized lunar pyroclastic deposits may have a more complex origin and mode of emplacement than previously thought.
ContributorsBennett, Kristen Alicia (Author) / Bell, James F. (Thesis advisor) / Christensen, Phillip (Committee member) / Clarke, Amanda (Committee member) / Robinson, Mark (Committee member) / Whipple, Kelin (Committee member) / Arizona State University (Publisher)
Created2016
Description
Planetary surface studies across a range of spatial scales are key to interpreting modern and ancient operative processes and to meeting strategic mission objectives for robotic planetary science exploration. At the meter-scale and below, planetary regolith conducts heat at a rate that depends on the physical properties of the regolith particles, such as particle size, sorting, composition, and shape. Radiometric temperature measurements thus provide the means to determine regolith properties and rock abundance from afar. However, heat conduction through a matrix of irregular particles is a complicated physical system that is strongly influenced by temperature and atmospheric gas pressure. A series of new regolith thermal conductivity experiments were conducted under realistic planetary surface pressure and temperature conditions. A new model is put forth to describe the radiative, solid, and gaseous conduction terms of regolith on Earth, Mars, and airless bodies. These results will be used to infer particle size distribution from temperature measurements of the primitive asteroid Bennu to aid in OSIRIS-REx sampling site selection. Moving up in scale, fluvial processes are extremely influential in shaping Earth's surface and likely played an influential role on ancient Mars. Amphitheater-headed canyons are found on both planets, but conditions necessary for their development have been debated for many years. A spatial analysis of canyon form distribution with respect to local stratigraphy at the Escalante River and on Tarantula Mesa, Utah, indicates that canyon distribution is most closely related to variations in local rock strata, rather than groundwater spring intensity or climate variations. This implies that amphitheater-headed canyons are not simple markers of groundwater seepage erosion or megaflooding. Finally, at the largest scale, volcanism has significantly altered the surface characteristics of Earth and Mars. A field campaign was conducted in Hawaii to investigate the December 1974 Kilauea lava flow, where it was found that lava coils formed in an analogous manner to those found in Athabasca Valles, Mars. The location and size of the coils may be used as indicators of local effusion rate, viscosity, and crustal thickness.
ContributorsRyan, Andrew J (Author) / Christensen, Philip R. (Thesis advisor) / Bell, James F. (Committee member) / Whipple, Kelin X (Committee member) / Ruff, Steven W (Committee member) / Asphaug, Erik I (Committee member) / Arizona State University (Publisher)
Created2018
Description
There are more than 20 active missions exploring planets and small bodies beyond Earth in our solar system today. Many more have completed their journeys or will soon begin. Each spacecraft has a suite of instruments and sensors that provide a treasure trove of data that scientists use to advance our understanding of the past, present, and future of the solar system and universe. As more missions come online and the volume of data increases, it becomes more difficult for scientists to analyze these complex data at the desired pace. There is a need for systems that can rapidly and intelligently extract information from planetary instrument datasets and prioritize the most promising, novel, or relevant observations for scientific analysis. Machine learning methods can serve this need in a variety of ways: by uncovering patterns or features of interest in large, complex datasets that are difficult for humans to analyze; by inspiring new hypotheses based on structure and patterns revealed in data; or by automating tedious or time-consuming tasks. In this dissertation, I present machine learning solutions to enhance the tactical planning process for the Mars Science Laboratory Curiosity rover and future tactically-planned missions, as well as the science analysis process for archived and ongoing orbital imaging investigations such as the High Resolution Imaging Science Experiment (HiRISE) at Mars. These include detecting novel geology in multispectral images and active nuclear spectroscopy data, analyzing the intrinsic variability in active nuclear spectroscopy data with respect to elemental geochemistry, automating tedious image review processes, and monitoring changes in surface features such as impact craters in orbital remote sensing images. Collectively, this dissertation shows how machine learning can be a powerful tool for facilitating scientific discovery during active exploration missions and in retrospective analysis of archived data.
ContributorsKerner, Hannah Rae (Author) / Bell, James F. (Thesis advisor) / Ben Amor, Heni (Thesis advisor) / Wagstaff, Kiri L (Committee member) / Hardgrove, Craig J (Committee member) / Shirzaei, Manoochehr (Committee member) / Arizona State University (Publisher)
Created2019