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Articles 1 - 10 of 10
Full-Text Articles in Astrophysics and Astronomy
Automated Identification And Mapping Of Interesting Mineral Spectra In Crism Images, Arun M. Saranathan
Automated Identification And Mapping Of Interesting Mineral Spectra In Crism Images, Arun M. Saranathan
Doctoral Dissertations
The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) has proven to be an invaluable tool for the mineralogical analysis of the Martian surface. It has been crucial in identifying and mapping the spatial extents of various minerals. Primarily, the identification and mapping of these mineral spectral-shapes have been performed manually. Given the size of the CRISM image dataset, manual analysis of the full dataset would be arduous/infeasible. This dissertation attempts to address this issue by describing an (machine learning based) automated processing pipeline for CRISM data that can be used to identify and map the unique mineral signatures present in …
Hyperspectral Unmixing: A Theoretical Aspect And Applications To Crism Data Processing, Yuki Itoh
Hyperspectral Unmixing: A Theoretical Aspect And Applications To Crism Data Processing, Yuki Itoh
Doctoral Dissertations
Hyperspectral imaging has been deployed in earth and planetary remote sensing, and has contributed the development of new methods for monitoring the earth environment and new discoveries in planetary science. It has given scientists and engineers a new way to observe the surface of earth and planetary bodies by measuring the spectroscopic spectrum at a pixel scale. Hyperspectal images require complex processing before practical use. One of the important goals of hyperspectral imaging is to obtain the images of reflectance spectrum. A raw image obtained by hyperspectral remote sensing usually undergoes conversion to a physical quantity representing the intensity of …
Surface Modification Of Icy Satellites: Space Weathering Of The Large Moons Of Uranus And Alluvial Fan Formation On Saturn’S Moon Titan, Richard John Cartwright
Surface Modification Of Icy Satellites: Space Weathering Of The Large Moons Of Uranus And Alluvial Fan Formation On Saturn’S Moon Titan, Richard John Cartwright
Doctoral Dissertations
The surfaces of icy satellites are continually modified by space weathering and geologic processes. This dissertation explores the processes changing the surface compositions of the large moons of Uranus and mechanisms for development of possible alluvial fans on the Saturnian moon, Titan. On the Uranian satellites, I hypothesize that the origin and distribution of carbon dioxide ice results from charged particle bombardment, and that spectrally red material originated on retrograde irregular satellites. On Titan, I hypothesize that landforms identified as alluvial fans at low and mid latitudes were formed by sheetfloods, whereas possible alluvial fans at high latitudes were formed …
Remote Neutron Spectroscopy On Mars, Christopher Gayle Tate
Remote Neutron Spectroscopy On Mars, Christopher Gayle Tate
Doctoral Dissertations
Remote neutron spectroscopy is an important technique in planetary science that allows for classification of the amount of light elements in a planetary regolith. It is especially suited for studying hydrogen abundances and elements with high thermal neutron absorption cross sections in the top ~1 meter of regolith. The Mars Science Laboratory rover Curiosity carries the first rover based neutron spectrometer Dynamic Albedo of Neutrons (DAN) in Gale crater, Mars. As the DAN instrument operates in passive mode, it is sensitive to neutrons produced through Galactic Cosmic Ray interactions and neutrons generated by the rover's Multi-Mission Radioisotope Thermoelectric Generator. In …
Solar Modulation Of The Cosmic Ray Intensity And The Measurement Of The Cerenkov Reemission In Nova’S Liquid Scintillator, Philip James Mason
Solar Modulation Of The Cosmic Ray Intensity And The Measurement Of The Cerenkov Reemission In Nova’S Liquid Scintillator, Philip James Mason
Doctoral Dissertations
The NOνA (NuMI Off-axis electron neutrino Appearance) experiment is a long baseline neutrino oscillation experiment at Fermi National Accelerator Laboratory. Its purpose is to observe the oscillation of νμ (muon neutrino) to νe (electron neutrino) and to investigate the neutrino mass hierarchy and CP violation in the neutrino sector. Two detectors have been built for this purpose, a Near Detector 300 feet underground at Fermilab, and a Far Detector, on the surface at Ash River, Minnesota.
The completion of NOνA’s Far Detector in October 2014 enabled not only the recent measurement of neutrino oscillations, but an array of …
Insights Into Planetesimal Evolution: Petrological Investigations Of Regolithic Howardites And Carbonaceous Chondrite Impact Melts, Nicole Gabriel Lunning
Insights Into Planetesimal Evolution: Petrological Investigations Of Regolithic Howardites And Carbonaceous Chondrite Impact Melts, Nicole Gabriel Lunning
Doctoral Dissertations
Asteroidal meteorites are the only available geologic samples from the early part of our solar system’s history. These meteorites contain evidence regarding how the earliest protoplanetary bodies formed and evolved. I use petrological and geochemical techniques to investigate the evolution of these early planetesimals, focusing on two meteorite types: Howardites, which are brecciated samples of a differentiated parent body (thought to be the asteroid 4 Vesta), and CV chondrites, which are primitive chondrites that have not undergone differentiation on their parent body.
Quantitative petrological analysis and characterization of paired regolithic (solar wind-rich) howardites indicate that this large sample of the …
Direct Measurement Of The Pp Solar Neutrino Interaction Rate In Borexino, Keith Otis
Direct Measurement Of The Pp Solar Neutrino Interaction Rate In Borexino, Keith Otis
Doctoral Dissertations
This dissertation presents the first direct detection of pp solar neutrinos within Borexino, the underground liquid-scintilator detector located at the Gran Sasso National Labratory(LNGS) in Italy, designed to measure the interaction of neutrinos through neutrino-electron elastic scattering. The rate of scattering in Borexino from the pp solar neutrino spectrum is measured to be 155 +/- 16(stat) +/- 13(sys) counts per day per 100 tonnes. With this measurement we are able to rule out the no oscillation hypothesis at the 2-sigma C.L. and the results agree with Standard Solar Model predictions within 1.1-sigma. These neutrinos are from the keystone proton-proton fusion …
Nature And Degree Of Aqueous Alteration Of Outer Main Belt Asteroids And Cm And Ci Carbonaceous Chondrites, Driss Takir
Nature And Degree Of Aqueous Alteration Of Outer Main Belt Asteroids And Cm And Ci Carbonaceous Chondrites, Driss Takir
Doctoral Dissertations
CM (Mighei-like) and CI (Ivuna-like) carbonaceous chondrites are primitive meteorites that consist of some of the most pristine matter known in the Solar System. They are thought to be genetically related to outer Main Belt asteroids (C-, D-, G-, F-, T-, and B-types) that span the 2.5 < a < 4.0 AU region. They are also thought to be the source that might have delivered water and organics to terrestrial planets during their accretion. The goal of this dissertation is to develop reliable 3-µm [micron] spectral indicators that can place constraints on the degree and location of aqueous alteration in the outer Main Belt region, and on the nature of phyllosilicate mineralogy on the surface of these asteroids. To that end, we have undertaken combined petrologic, geochemical, and spectroscopic analyses of CM and CI chondrites and outer Main Belt asteroids. Using the SpeX spectrograph/imager at NASA Infrared Telescope Facility (IRTF), we measured near-infrared (NIR: 0.7-4.0 µm) spectra of 40 outer Main Belt asteroids that allowed the identification of four 3-µm spectral groups, each of which presumably reflects a distinct surface mineralogy. We also measured spectra of 9 CM chondrites (in addition to the CI chondrite Ivuna) in the laboratory under asteroid-like conditions. These measurements revealed three spectral groups of CM chondrites, all of which are distinct from the spectrum of Ivuna on the basis of the 3-μm band center and shape of spectra, showing that distinct parent body aqueous alteration environments experienced by different carbonaceous chondrites can be distinguished using reflectance spectroscopy. All CM and CI chondrites in the present study are found to be similar to the group of asteroids that are located in the 2.5 < a < 3.3 AU region and exhibit a sharp 3-µm feature, attributed to OH-stretching in hydrated minerals. However, no meteorite match was found for asteroids with a rounded 3-µm feature that are located farther from the Sun (3.0 < a < 4.0 AU), or for groups with distinctive spectra like 1 Ceres or 52 Europa.
Martian Dune Fields: Aeolian Activity, Morphology, Sediment Pathways, And Provenance, Matthew Chojnacki
Martian Dune Fields: Aeolian Activity, Morphology, Sediment Pathways, And Provenance, Matthew Chojnacki
Doctoral Dissertations
Wind has likely been the dominant geologic agent for most of Mars’ history. The wide-spread nature of sand dunes there shows that near-surface winds have commonly interacted with plentiful mobile sediments. Early studies of these dunes suggested minimal activity, dominantly unidirectional simple dune morphologies, and little variations in basaltic sand compositions. This dissertation examines martian sand dunes and aeolian systems, in terms of their activity, morphologies, thermophysical properties, sand compositions, geologic contexts, and source-lithologies using new higher-resolution orbital data. Although previous evidence for contemporary dune activity has been limited, results presented in Chapter II show substantial activity in Endeavour Crater, …
Characterizing Phyllosilicate Distribution, Abundance, And Origin On Mars, Christina Elizabeth Viviano
Characterizing Phyllosilicate Distribution, Abundance, And Origin On Mars, Christina Elizabeth Viviano
Doctoral Dissertations
Secondary phyllosilicates are hydrated minerals formed in the presence of liquid water. On Earth, their formation is often indicative of a neutral, water-rich environment, capable of supporting and preserving organic matter. Different phyllosilicate species may be produced in different pH levels and water-to-rock ratios. The identification of mineralogically diverse phyllosilicates in small, localized exposures on Mars provides a complex record of their formation processes. While discrete outcrops of phyllosilicates have been previously identified in high-resolution visible/near-infrared images of Mars, regional coverage of these phyllosilicate-rich areas at better resolution is limited. Furthermore, spectra of minerals in this wavelength range do not …