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Articles 1 - 20 of 20
Full-Text Articles in Physical Processes
Characterizing The Earth's Magnetosheath With In Situ Measurements, Hector A. Salinas
Characterizing The Earth's Magnetosheath With In Situ Measurements, Hector A. Salinas
Physics Dissertations - Archive
Earth’s magnetosheath is a region of shocked plasma that mediates energy and momentum transfer from the solar wind to the magnetosphere. The dynamics and thus the plasma structures of this region are highly dependent on upstream solar wind conditions. As such, the region is often characterized as a turbulent environment, with the most intense periods of turbulence occurring often under quasi-parallel bow shock conditions. This magnetosheath turbulence displays as variable and large-scale fluctuations with in-situ measurements. Given that turbulence is a characteristic feature of the magnetosheath, this dissertation asks two questions: (1) How are plasma structures inside the sheath affected …
A Systematic Study Of Planetary Envelope Growth With 3d Radiation-Hydrodynamics Simulations, Avery Bailey, James M. Stone, Jeffrey Fung
A Systematic Study Of Planetary Envelope Growth With 3d Radiation-Hydrodynamics Simulations, Avery Bailey, James M. Stone, Jeffrey Fung
Physics & Astronomy Faculty Research
In the core accretion model of planet formation, envelope cooling regulates the accretion of material and ultimately sets the time-scale to form a giant planet. Given the diversity of planet-forming environments, opacity uncertainties, and the advective transport of energy by three-dimensional (3D) recycling flows, it is unclear whether one-dimensional models can adequately describe envelope structure and accretion in all regimes. Even in 3D models, it is unclear whether approximate radiative transfer methods sufficiently model envelope cooling, particularly at the planetary photosphere. To address these uncertainties, we present a suite of 3D radiation-hydrodynamics simulations employing methods that directly solve the transfer …
Ratification Of The Base Of The Ics Geological Time Scale: The Global Standard Stratigraphic Age (Gssa) For The Hadean Lower Boundary, Janna Halla, Nora Noffke, Humberto Reis, Stanley Awramik, Andrey Bekker, Alexander Brasier, Flávia Callefo, Adrita Choudhury, Jan-Peter Duda, Christopher Fedo, Douglas Galante, Jessica Haddock, Peter Haines, Linda Hinnov, Axel Hofmann, Martin Homann, David Huston, Simon Johnson, Linda Kah, Martin Whitehouse, Et Al.
Ratification Of The Base Of The Ics Geological Time Scale: The Global Standard Stratigraphic Age (Gssa) For The Hadean Lower Boundary, Janna Halla, Nora Noffke, Humberto Reis, Stanley Awramik, Andrey Bekker, Alexander Brasier, Flávia Callefo, Adrita Choudhury, Jan-Peter Duda, Christopher Fedo, Douglas Galante, Jessica Haddock, Peter Haines, Linda Hinnov, Axel Hofmann, Martin Homann, David Huston, Simon Johnson, Linda Kah, Martin Whitehouse, Et Al.
OES Faculty Publications
The base of the ICS (International Commission on Stratigraphy) Geological Time Scale was ratified in 2022 by defining a new Global Stratigraphic Standard Age (GSSA) for the lower boundary of the Hadean Eon (formerly 4000-3600 Ma); the age of the Solar System based on the oldest solids, calcium-aluminium inclusions (CAIs), generated in the protoplanetary disk. The formal GSSA for the Hadean base is the oldest reliable, weighted mean U-corrected Pb-Pb age of 4567.30 ± 0.16 Ma obtained for CAIs in primitive meteorites Allende and Efremovka. This age is supported by the 4568-4567 Ma U-corrected Pb-Pb ages of chondrules in Northwest …
Microstructural, Mineralogical, And Chemical Characterization Of The Handys Bend And Flax Creek Meteorites, Kentucky: Relevance For The Iron Meteorite Record, Ethan S.L. Davis
Microstructural, Mineralogical, And Chemical Characterization Of The Handys Bend And Flax Creek Meteorites, Kentucky: Relevance For The Iron Meteorite Record, Ethan S.L. Davis
Theses and Dissertations--Earth and Environmental Sciences
Iron meteorites remain the only material view into planetary cores. Despite their scientific relevance, iron meteorites are relatively rare. In June 2021 and March 2022, the Kentucky Geological Survey received requests to identify two metallic specimens discovered in central Kentucky. The specimens were given the provisional names Handys Bend (3175.2 g) and Flax Creek (286.2 g). The goal of this project is to confirm meteoritic origin, characterize their structures and chemistry, assign genetic classifications, and examine potential relations to previous discoveries. Petrography was conducted using scanning electron microscopy. Mineral phases were examined using X-Ray diffraction crystallography. Chemical compositions were determined …
The Effects Of Environmental Factors On Tsunami Propagation And Inundation: A Comparison Of Earth With Other Planetary Bodies, Austin Halstead
The Effects Of Environmental Factors On Tsunami Propagation And Inundation: A Comparison Of Earth With Other Planetary Bodies, Austin Halstead
All Master's Theses
Tsunamis are a universal hazard in any environment with oceans or lakes. Having a firm understanding of them is essential because of this. However, the vast number of tsunami studies have been solely on Earth, despite the growing evidence of oceans and lakes being on, or having once existed on, other planets and moons. In this study, I investigated tsunami behavior in non-Earth environments by testing the effects of varying viscosity and gravity. I conducted simulations using GeoClaw, Flow3D®, and VolcFlow on established tsunami benchmarks to identify consistent patterns in tsunami flow patterns and inundation. The results show …
Mms Observations Of The Kelvin-Helmholtz Instability And Associated Ion Scale Waves, Rachel C. Rice
Mms Observations Of The Kelvin-Helmholtz Instability And Associated Ion Scale Waves, Rachel C. Rice
Doctoral Dissertations and Master's Theses
The detailed mechanisms coupling the solar wind to Earth's magnetosphere are not yet fully understood. Solar wind plasma is heated non-adiabatically as it penetrates the magnetosphere, and this process must span scale sizes. Reconnection alone is not able to account for the observed heating; other mechanisms must be at work. One potential process is the Kelvin-Helmholtz instability (KHI). The KHI is a convective instability which operates at the fluid scale in plasmas, but is capable of driving secondary process at smaller scales. Previous work has shown evidence of magnetic reconnection, various ion scale wave modes, mode conversion, and turbulence associated …
Initial Acoustoelastic Measurements In Olivine: Investigating The Effect Of Stress On P- And S-Wave Velocities, Taryn K. Traylor, Pamela C. Burnley, M. L. Whitaker
Initial Acoustoelastic Measurements In Olivine: Investigating The Effect Of Stress On P- And S-Wave Velocities, Taryn K. Traylor, Pamela C. Burnley, M. L. Whitaker
Geoscience Faculty Research
It is well known that elasticity is a key physical property in the determination of the structure and composition of the Earth and provides critical information for the interpretation of seismic data. This study investigates the stress-induced variation in elastic wave velocities, known as the acoustoelastic effect, in San Carlos olivine. A recently developed experimental ultrasonic acoustic system, the Directly Integrated Acoustic System Combined with Pressure Experiments (DIASCoPE), was used with the D-DIA multi-anvil apparatus to transmit ultrasonic sound waves and collect the reflections. We use the DIASCoPE to obtain longitudinal (P) and shear (S) elastic wave velocities from San …
The Morphology And Evolution Of Transverse Aeolian Ridges On Mars, Timothy Paul Nagle-Mcnaughton
The Morphology And Evolution Of Transverse Aeolian Ridges On Mars, Timothy Paul Nagle-Mcnaughton
Earth and Planetary Sciences ETDs
Transverse aeolian ridges (TARs) are enigmatic and largely relict bedforms on the surface of Mars. TARs are sparsely distributed but common on Mars, but their history, preservation, and past role in the sediment cycle is not well understood. First described in 2003, and detailed extensively in 2008, our study of TARs has been narrowly focused in the last decade, with more and more research noting their presence, but little investigation of the features themselves. Recent work has mostly focused on identifying Terran analogues for TARs, but TARs remain largely a unique Martian feature. In this manuscript, I clarify and refine …
The Undeniable Attraction Of Lunar Swirls, Dany Waller
The Undeniable Attraction Of Lunar Swirls, Dany Waller
Posters-at-the-Capitol Presentations
Lunar swirls are complex patterns on the Moon with distinct brightness signatures and magnetic characteristics. Current research has suggested that the formation of lunar swirls relies on local magnetic fields to shield impinging solar wind, based on a shift in electromagnetic wavelength peaks related to solar radiation and space weathering. Our research combined recent models and methods to characterize these anomalies at the surface of the Moon, exploring the effects of field strength and position. We have produced a high resolution map of a famous swirl named Reiner Gamma using magnetic dipole modeling. These maps and models are considered when …
The Undeniable Attraction Of Lunar Swirls, Cierra Waller, Dhananjay Ravat
The Undeniable Attraction Of Lunar Swirls, Cierra Waller, Dhananjay Ravat
Posters-at-the-Capitol
Lunar swirls are complex patterns on the Moon with distinct brightness signatures and magnetic characteristics. Current research has suggested that the formation of lunar swirls relies on local magnetic fields to shield impinging solar wind, based on a shift in electromagnetic wavelength peaks related to solar radiation and space weathering. Our research combined recent models and methods to characterize these anomalies at the surface of the Moon, exploring the effects of field strength and position. We have produced a high resolution map of a famous swirl named Reiner Gamma using magnetic dipole modeling. These maps and models are considered when …
Differentiation In Impact Melt Sheets As A Mechanism To Produce Evolved Magmas On Mars, Ari Koeppel
Differentiation In Impact Melt Sheets As A Mechanism To Produce Evolved Magmas On Mars, Ari Koeppel
Dissertations and Theses
Asteroid bombardment contributed to extensive melting and resurfacing of ancient (> 3 Ga) Mars, thereby influencing the early evolution of the Martian crust. However, information about how impact melting has altered Mars’ crustal petrology is limited. Evidence from some of the largest impact structures on Earth, such as Sudbury and Manicouagan, suggests that some impact melt sheets experience chemical differentiation. If these processes occur on Mars, we expect to observe differentiated igneous materials in some exhumed rock samples. Some rocks observed in Gale crater are enriched in alkalis (up to 14 wt% Na2O + K2O) and …
Martian Cave Air-Movement Via Helmholtz Resonance, Kaj E. Williams, Timothy N. Titus, Chris H. Okubo, Glen E. Cushing
Martian Cave Air-Movement Via Helmholtz Resonance, Kaj E. Williams, Timothy N. Titus, Chris H. Okubo, Glen E. Cushing
International Journal of Speleology
Infrasonic resonance has previously been measured in terrestrial caves by other researchers, where Helmholtz resonance has been suggested as the plausible mechanism resulting in periodic wind reversals within cave entrances. We extend this reasoning to possible Martian caves, where we examine the characteristics of four atypical pit craters (APCs) on Tharsis, suggested as candidate cave entrance locations. The results show that, for several possible cave air movement periods, we are able to infer the approximate cave volumes. The utility of inferring cave volumes for planetary cave exploration is discussed.
Infrared Spectra Analysis Of Thermally Altered Iron Phyllosilicates And The Implications For Mars, William Thomas Bryan
Infrared Spectra Analysis Of Thermally Altered Iron Phyllosilicates And The Implications For Mars, William Thomas Bryan
Graduate Theses and Dissertations
This study looks at two iron-rich phyllosilicates, which may be present on Mars. The minerals, greenalite and hisingerite, are rich in iron-II and iron-III, respectively. Small samples (~0.40 grams) of each mineral were crushed and heated in a Lindberg Tube Oven for approximately twenty-four hours at temperatures selected to mimic lava flows and impact events. Following heating, each sample was placed in a Fourier Transform Infrared (FT-IR) spectrometer to collect the near- and mid-infrared spectra. The spectra allowed for these terrestrial analogs to be analyzed with regards to how their structure breaks down with increasing temperature. The samples' colors were …
Electric Currents Due To Stress-Activated Positive Hole Charge Carriers In Ice, Cary T. Keller P.E., Friedemann T. Freund, Dale P. Cruikshank
Electric Currents Due To Stress-Activated Positive Hole Charge Carriers In Ice, Cary T. Keller P.E., Friedemann T. Freund, Dale P. Cruikshank
STAR Program Research Presentations
Jupiter’s satellite Europa, whose surface is composed of ice with a possible water ocean beneath, could conceivably serve as an abode for extraterrestrial life. This and other icy celestial bodies may contain organic macromolecular solid material that is produced when surface ices are exposed to ultraviolet radiation and/or electrical energy. Tidal and tectonic stresses or meteorite impacts in icy crusts may produce electrical discharges, which would provide the energy for in-situ synthesis of the organic solids. This electrical energy can be provided by positive hole charge carrier activation. Positive holes exhibit properties such as the ability to flow out of …
Subsurface Planetary Investigation Techniques And Their Role For Assessing Subsurface Planetary Composition, Ahmed Elshafie
Subsurface Planetary Investigation Techniques And Their Role For Assessing Subsurface Planetary Composition, Ahmed Elshafie
Graduate Theses and Dissertations
Subsurface planetary investigation techniques are of high interest and importance for the scientific community. Not only they can enhance our knowledge of the history of planetary formation but also can lead to information about its future. Whether the investigation is being conducted remotely using imagers, radars or physically using penetrometers or drills, a pre-existed knowledge of the mechanical and electrical properties of the subsurface regolith should be acquired for better data interpretation and analysis. Therefore, the main objective of this work is to investigate the mechanical and electrical properties of planetary analogs, understand their role for assessing the subsurface structure …
Laboratory Astrophysics: Using Ebit Measurements To Interpret High Resolution Spectra From Celestial Sources, Carey Scott, Joshua Thompson, N. Hell, Greg V. Brown
Laboratory Astrophysics: Using Ebit Measurements To Interpret High Resolution Spectra From Celestial Sources, Carey Scott, Joshua Thompson, N. Hell, Greg V. Brown
STAR Program Research Presentations
Astrophysicists use radiation to investigate the physics controlling a variety of celestial sources, including stellar atmospheres, black holes, and binary systems. By measuring the spectrum of the emitted radiation, astrophysicists can determine a source’s temperature and composition. Accurate atomic data are needed for reliably interpreting these spectra. Here we present an overview of how LLNL’s EBIT facility is used to put the atomic data on sound footing for use by the high energy astrophysics community.
Serpentinite Weathering And Implications For Mars, Valerie Tu, Julie Baumeister, Rodney Metcalf, A. Olsen, Elisabeth Hausrath
Serpentinite Weathering And Implications For Mars, Valerie Tu, Julie Baumeister, Rodney Metcalf, A. Olsen, Elisabeth Hausrath
Festival of Communities: UG Symposium (Posters)
In the search for life on Mars near-surface soil environments may be important habitats for life accessible to future missions. Serpentinite rocks have been documented on Mars, as well as other clay minerals including smectite and kaolinites. Previous studies of soils formed on serpentinites on Earth have documented the formation of extensive clays. Serpentinites are additionally of interest as habitats for life such as methanogens. Here we examine weathering of serpentinites from bedrock to soil surface, as a potential route for the formation of clay minerals on Mars from abundant ultramafic minerals. We additionally test for the presence of Fe-oxidizing …
The Interaction Of Rock And Water During Shock Decompression: A Hybrid Model For Fluidized Ejecta Formation, Audrey Hughes Rager
The Interaction Of Rock And Water During Shock Decompression: A Hybrid Model For Fluidized Ejecta Formation, Audrey Hughes Rager
UNLV Theses, Dissertations, Professional Papers, and Capstones
Crater and ejecta morphology provide insight into the composition and structure of the target material. Martian rampart craters, with their unusual single-layered (SLE), double-layered (DLE), and multi-layered ejecta (MLE), are the subject of particular interest among planetary geologists because these morphologies are thought to result from the presence of water in the target. Also of interest are radial lines extending from the crater rim to the distal rampart of DLE craters. Exactly how these layered ejecta morphologies and radial lines form is not known, but they are generally thought to result from interaction of the ejecta with the atmosphere, subsurface …
The Exterior Orientation Of Aerial Imagery Using Existing Orthoimagery And Terrain Models:A Performance Test, Finnian O'Cionnaith
The Exterior Orientation Of Aerial Imagery Using Existing Orthoimagery And Terrain Models:A Performance Test, Finnian O'Cionnaith
Masters
In every part of the world the rate of map revision is alarmingly low when compared to the rate of change of many human influenced surface features. There is therefore a requirement to regularly gather up-to-date information about surface features and to incorporate changes in maps both quickly and effectively before it becomes history. When an aerial photograph is taken, it contains errors one category of which is caused by the aircraft taking the photograph being tilted. This aerial photograph by itself is of little commercial value. Accurate maps cannot be created from it, its use in GIS (Geographical Information …
Testing Of The New Usgs K Index Algorithm At Bear Lake, Ariel O. Acebal
Testing Of The New Usgs K Index Algorithm At Bear Lake, Ariel O. Acebal
All U.S. Government Documents (Utah Regional Depository)
The K index was developed by Bartels in 1939 as an estimate of the level of geomagnetic activity caused by the Sun. This index was computed manually every three hours at geomagnetic observatories using the magnetic traces of the surface planetary magnetic field. In 1991, the International Association of Geomagnetism and Aeronomy approved four additional methods to compute the K index; all of them were computer algorithms. One of the approved methods, the Wilson code, recently underwent some modifications. The new algorithm is now part of a Windows-based computer program being developed by the United States Geological Survey (USGS). After …