Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
Browse
16 results
Search Results
Item Advancing airborne and spaceborne synthetic aperture radar measurements of ice and snow in the northern Great Plains(Montana State University - Bozeman, College of Letters & Science, 2023) Palomaki, Ross Theodore; Chairperson, Graduate Committee: Eric A. Sproles; This is a manuscript style paper that includes co-authored chapters.The cryosphere is responding to climate change in ways that have negatively impacted socio-environmental systems. Accurate and timely observations of the cryosphere are critical to adapting our infrastructure to these rapid changes. This dissertation contributes novel approaches to validating synthetic aperture radar (SAR) measurements over river ice and seasonal prairie snow. Previous C-band SAR-based river ice studies typically validate regional ice cover maps using aerial photos of frozen rivers. This qualitative approach relies on the principle that visually rougher ice should result in stronger SAR backscatter. In Chapter 2 of this dissertation I present the first systematic, quantitative investigation of the effect of river ice surface roughness on C-band Sentinel-1 backscatter. I employ Random Forest algorithms first to replicate qualitative classification results from previous studies, and then as regression models to explore relationships between Sentinel-1 backscatter and novel, quantitative surface roughness metrics derived from drone-based Structure-from-Motion datasets. Classification accuracies are similar to those reported in previous studies, but poor regression performance indicates a weak relationship between river ice roughness and Sentinel-1 backscatter. In Chapter 3, I extend these drone-based surface measurements of river ice with GPR-based subsurface measurements. Results from this smaller, richer dataset demonstrate that Sentinel-1 VV backscatter is correlated with ice thickness and VH backscatter with structural properties, but results are site-specific and more work is necessary to create generalized river ice models from Sentinel-1 measurements. Interferometric SAR techniques have been used to estimate snow water equivalent (SWE) using L-band measurements from the UAVSAR platform. These methods have been developed in mountainous areas and have not been investigated over prairie snowpacks, which typically feature exposed agricultural vegetation and greater spatial variability than found in mountain snowpacks. In Chapter 4 I develop a rigorous statistical framework to demonstrate that UAVSAR measurements over prairie snowpacks are sensitive to small changes in SWE, and are relatively unaffected by exposed agricultural vegetation. However, sub-pixel snow depth variability decreases the accuracy of SWE estimates derived from UAVSAR measurements. The upcoming NISAR satellite mission provides an opportunity to extend this work with repeated L-band measurements over a wider range of prairie snow conditions.Item Investigations of the properties of radiation belt electron precipitation observed by the FIREBIRD-II CubeSats(Montana State University - Bozeman, College of Letters & Science, 2022) Johnson, Arlo Thomas; Chairperson, Graduate Committee: John Sample; This is a manuscript style paper that includes co-authored chapters.High energy electrons can be trapped by the Earth's magnetic field in regions known as the radiation belts. Some of these electrons will impact the upper atmosphere and be lost from the radiation belt system in a process known as electron precipitation. This dissertation explores two questions regarding electron precipitation using data from the focused investigations of relativistic electron burst intensity, range, and dynamics II CubeSat mission. The first question was to determine the energy dependence of specific type of impulsive precipitation known as a microburst, which may be a significant contributer to electron loss from the radiation belts. A statistical study of several hundred microbursts was performed and the energy spectrum was found to generally be exponential with a wide rage of possible parameters depending in part on the level of geomagnetic activity. In addition, comparison of this spectrum with the rest of the radiation belt population revealed that microbursts are a more effective loss mechanism for electrons with relatively lower energies. The second question addresses the possibility of inducing electron precipitation using magnetospheric waves artificially generated by a spacecraft. Waves of 3.0 or 8.2 kHz were excited in the magnetosphere by the Demonstration and Science Experiments satellite and a related signature was searched for in the precipitating electrons. There was no evidence of additional precipitating electrons, so an sensitivity estimate was carried out to place boundaries on the diffusion rates needed to create a measurable precipitation signature. It was found that in many cases a diffusion rate similar to those driven by naturally occurring waves was required, but in cases with a high number of electrons available to interact with the waves the diffusion rates could be orders of magnitude weaker and still produce a measurable amount of precipitation.Item An operational methodology for validating satellite-based snow albedo measurements using a UAV(Montana State University - Bozeman, College of Letters & Science, 2021) Mullen, Andrew Louiselle; Chairperson, Graduate Committee: Eric A. Sproles; Eric A. Sproles, Jordy Hendrikx, Joseph A. Shaw and Charles K. Gatebe were co-authors of the article, 'An operational methodology for validating satellite-based snow albedo measurements using a UAV' submitted to the journal 'Frontiers in remote sensing' which is contained within this thesis.The albedo, or reflectivity, of seasonal snowpack directly controls the timing and magnitude of snowmelt and runoff. Snow albedo is affected by a large number of snow physical and environmental properties that vary considerably at multiple spatiotemporal scales. This variability introduces a high degree of uncertainty into existing modeling techniques. Models for snowmelt that require snow albedo can be improved by incorporating satellite measurements to inform and update estimates of this snow property. However, satellite measurements are susceptible to a multitude of error sources, which requires them to be calibrated and validated by means of ground-based measurements. Ground-based measurements from automated weather stations are often located at sparsely-distributed monitoring sites in homogeneous meadow environments. These spatially restricted in-situ data provide biased validation and calibration data that are not representative of the heterogeneous landscapes that comprise many seasonally snow-covered watersheds. In order to provide comprehensive validation and calibration of satellite albedo products, multiple near-surface measurements should be taken across large areas to capture the high degree of spatial variability that snow albedo can exhibit. UAV albedo measurements can be used to bridge the scaling gap between satellite and point-based measurements. Since these platforms are in a novel stage, the requisite methodologies for topographic correction and comparison to gridded albedo products do not exist. Additionally, there lacks a general understanding of the spatial scaling of albedo measurements in heterogeneous terrain. This research aims to develop these methodologies and provide a comprehensive understanding of how to deploy these platforms and properly interpret their measurements. We first developed and validated a topographic correction using ground-based measurements of snow albedo in a sloping alpine meadow. Sensitivity analyses on both ground validation measurements and UAV-based albedo surveys in our alpine study area highlight the implications of using different user-defined parameters for the proposed topographic correction and satellite comparison methods. Improvements to the methodology can be made in the way it accounts for trees, shading, and cloud cover. This research develops the initial steps requisite to the operationalization of UAV albedo measurements and standardization of the techniques.Item Connecting microburst precipitation to its scattering mechanism(Montana State University - Bozeman, College of Letters & Science, 2019) Shumko, Mykhaylo Sergeevich; Chairperson, Graduate Committee: John Sample; Drew L. Turner, T. P. O'Brien, Seth G. Claudepierre, John Sample, D. P. Hartley, Joseph Fennell, J. Bernard Blake, Matina Gkioulidou and Donald G. Mitchell were co-authors of the article, 'Evidence of microbursts observed near the equatorial plane in the outer Van Allen Radiation Belt' in the journal 'Geophysical research letters' which is contained within this thesis.; John Sample, Arlo Johnson, Bern Blake, Alex Crew, Harlan Spence, David Klumpar, Oleksiy Agapitov and Matthew Handley were co-authors of the article, 'Microburst scale size derived from multiple bounces of a microburst simultaneously observed with the Firebird-II cubesats' in the journal 'Geophysical research letters' which is contained within this thesis.; A.T. Johnson, J.G. Sample, B.A. Griffith, D.L. Turner, T.P. OBrien, O. Agapitov, J.B. Blake and S. G. Claudepierre were co-authors of the article, 'Microburst size distribution derived with Aerocube-6' submitted to the journal 'Geophysical research letters' which is contained within this thesis.We will review the main structures in the magnetosphere, the motion of charged particles in electric and magnetic fields, how particles are accelerated and lost in the magnetosphere, and asses the current state of our understanding of microbursts. Then the rest of this dissertation expands our knowledge of microbursts. In Chapter 2 we will investigate and model the scattering mechanism responsible for microbursts observed inside the outer radiation belt, near the magnetic equator. Then in Chapters 3 and 4 we will investigate the microburst scattering mechanism indirectly by estimating the microburst footprint size in low Earth orbit and the magnetic equator (near where microburst electrons are believed to be scattered) and compare it to sizes of chorus waves estimated in prior literature.Item Optimization of error correcting codes in FPGA fabric onboard cube satellites(Montana State University - Bozeman, College of Engineering, 2019) Tamke, Skylar Anthony; Chairperson, Graduate Committee: Brock LaMeresThe harmful effects of radiation on electronics in space is a difficult problem for the aerospace industry. Radiation can cause faults in electronics systems like memory corruption or logic flips. One possible solution to combat these effects is to use FPGAs with radiation mitigation techniques. The following Masters of Science thesis details the design and testing of a radiation tolerant computing system at MSU. The computer is implemented on a field programmable gate array (FPGA), the reconfigurable nature of FPGAs allows for novel fault mitigation techniques on commercial devices. Some common fault mitigation techniques involve triple modular redundancy, memory scrubbing, and error correction codes which when paired with the partial reconfiguration. Our radiation tolerant computer has been in development for over a decade at MSU and is continuously being developed to expand its radiation mitigation techniques. This thesis will discuss the benefits of adding error correcting codes to the ever developing radiation tolerant computing system. Error correcting codes have been around since the late 1940's when Richard Hamming decided that the Bell computers he did his work on could automate their own error correcting capabilities. Since then a variety of error correcting codes have been developed for use in different situations. This thesis will cover several popular error correcting method for RF communication and look at using them in memory in our radiation tolerant computing system.Item An electrical power system implementing fixed power point tracking with temperature compensation(Montana State University - Bozeman, College of Engineering, 2017) Zack, Kevin William; Chairperson, Graduate Committee: Brock LaMeresFor the past decade Montana State University (MSU) researchers have been developing a Radiation Tolerant Computing System (RTCS) to support the National Aeronautics and Space Administrations (NASA) technology road map for space technology. The next iteration of this effort is a free flying CubeSat being developed in the Electrical and Computer Engineering Department named RadSat-g. This thesis addresses the Electrical Power System (EPS) of the satellite avionics in support of RTCS for RadSat-g. One of the main problems that CubeSat developers face is the small amount of solar power generated due to available space for solar cell placement on the small frame of a CubeSat. Charging the battery from the solar panels generally employ one of two types of energy transfer methods, direct energy transfer and power point tracking. Direct energy transfer's disadvantage is the strings of solar cells need to be tuned to the battery and as such has the potential to leave valuable space on the solar panel unused. Power point tracking has the advantage of the ability to utilize variable string lengths, this allows each solar panel to have the maximum number of cells and therefore exploit the maximum available power. In terms of CubeSat power availability, the RTCS has a substantial power requirement, so power point tracking is required for the satellite to be power positive. To accommodate this requirement, a new EPS needed to be researched, designed and built. This new EPS, named Phoenix v2.3 EPS, meets the needs of the RadSat-g mission while leveraging components with flight heritage from past MSU Space Science Engineering and Laboratory missions.Item Design, fabrication, and implementation of an embedded flight computer in support of the ionospheric-thermospheric scanning photometer for ion-neutral studies CubeSat mission(Montana State University - Bozeman, College of Engineering, 2017) Handley, Matthew Lee; Chairperson, Graduate Committee: Brock LaMeresAs society increasingly relies on space-based assets for everything from GPS-based directions and global communications to human-driven research on the ISS, our understanding of space weather becomes vital. Timely predictions of a solar storm's impact on the ionosphere are imperative to safing these assets before damaging storms hit, while minimizing downtime during lighter storms. The topside transition region (TTR) is a global boundary where the concentration of O+ significantly decreases due to charge exchange with H+ and He+ from the thermosphere, as well as protons and neutral atomic oxygen from the plasmasphere. When high-energy electrons in the ionosphere intercept O+ ions, they combine and release photons at 135.6-nm. The Ionospheric-Thermospheric Scanning Photometer for Ion-Neutral Studies (IT-SPINS) mission will provide 135.6-nm nightglow measurements from a 3U CubeSat equipped with a high-sensitivity UV photometer. The CubeSat will spin about orbit normal, sweeping its photometer field of view through the ionosphere. Ground-based post processing will yield 2D altitude/in-track images of O+ density, providing weighting parameters for models of the TTR. This low-earth orbit (LEO) small satellite mission is a collaboration between the John Hopkins University Applied Physics Laboratory, SRI International, and Montana State University (MSU). This research describes the design, fabrication, and implementation of the space flight computer (SFC) hardware and software responsible for handling all commands, telemetry, and scientific data required by this National Science Foundation (NSF) funded mission. The SFC design balances requirements derived from the mission objectives while leveraging heritage hardware and software from MSU's many successful CubeSat missions (HRBE, FIREBIRD, FIREBIRD-II) and payloads (EPISEM) [1-3]. This low-power (100 mW) embedded computer features dual 16- bit PIC microcontrollers running at 16 MHz with only 96 kB of RAM and runs the microC/OS-II real-time operating system (RTOS). The SFC also includes a TCXO-driven mission elapsed time clock with plus or minus 2 ppm temperatures stability, a 1 GB NAND flash for data storage, and interfaces to all other subsystems in the satellite. The SFC has passed all standalone testing. It is currently being integrated and tested with the entire IT-SPINS spacecraft and is planned to fly in late 2018.Item Scaling and uncertainty in landsat remote sensing of biophysical attributes(Montana State University - Bozeman, College of Agriculture, 2015) Johnson, Aiden Vincent; Chairperson, Graduate Committee: Scott Powell; Paul Stoy, Nathaniel Brunsell, Stephanie Ewing, Scott Powell and Mark Greenwood were co-authors of the article, 'Change detection in the discontinuous permafrost zone using landsat: have surface features prone to pronounced methane efflux increased in spatial extent?' submitted to the journal 'Remote sensing' which is contained within this thesis.; Paul Stoy , Lucy Marshall and Joel McCorkel were co-authors of the article, 'Random uncertainty in land surface temperature calculated using landsat TM, ETM+, and TIRS' submitted to the journal 'Ecological applications' which is contained within this thesis.Monitoring environmental change is of high importance in our time of global change. Remote sensing technology provides the tools to view the ecological dynamics at a landscape scale and review the change through time with time series data availability. Creating congruence between data scales and functional scales is a long standing challenge for Earth system scientists. In this research we evaluate methods for change detection and scaling data in a discontinuous permafrost zone of central Alaska and is characterized by pronounced permafrost thaw and methane release over decadal to century timescales. The primary goal is to evaluate the applicability of Landsat satellite remote sensing for detecting bog thermal expansion over time. We implement a Random Forests classification scheme in order to separate the landscape into its various land features and bog types, many features in this landscape are developed through an aged-stage transition of thermal expansion. The results of this classification were dominated by hydrologic features, with a 0.05 increase in mean albedo, providing essentially no change in both mean Normalized Difference Vegetation Index (NDVI) and mean Brightness Temperature (BT). In addition, we attempt to capture the scales of variation within the landscape using multi-resolution methods. The scale of variance as illustrated by a wavelet analysis for NDVI show the greatest amount of variance around 4.5 km to 5 km. Brightness Temperature had three peaks of high variance between 0.06 km - 1 km including maximum variance at about 0.5 km and a pair of peaks between 3 km and 4 km. An important component of any data analysis is quantifying the uncertainty. Uncertainty quantification in remote sensing data analysis is often over looked. In a second analysis we attempt to quantify the primary sources of uncertainty in Landsat remote sensing data via simulation methods. Specifically, we evaluate the level of uncertainty contributed to the data by applying a typical atmospheric correction through Monte Carlo simulation approach to estimate the total variance within several Landsat scenes. We find the contribution of uncertainty due to the MODTRAN conversion to be between 7-27% differing by total scene variance per image.Item Wheat yield estimates using multi-temporal AVHRR-NDVI satellite imagery(Montana State University - Bozeman, College of Agriculture, 1999) Henry, Mari PatriciaItem Plant phenology in the western United States using the ERTS-1 satellite(Montana State University - Bozeman, College of Agriculture, 1976) Jones, Charles Moncur