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The LOw Frequency ARray (LOFAR) is a new and innovative radio telescope designed and constructed by the Netherlands Institute for Radio Astronomy (ASTRON). LOFAR unique capable of operating in very low frequencies (10-240 MHz) and consists of an extensive interferometry array of dipole antenna stations distributed throughout the Netherlands and Europe which allows it to achieve superb angular resolution. I investigate a part of the northern sky to search for rare radio objects such as radio haloes and radio relics that may have not been able to have been resolved by other radio telescopes.
ContributorsNguyen, Dustin Dinh (Author) / Scannapieco, Evan (Thesis director) / Butler, Nathaniel (Committee member) / School of Earth and Space Exploration (Contributor) / Department of Physics (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
The aerospace industry has been conducting research on the additive manufacturing (AM) process since the 1980's, but companies have recently just begun to apply AM in hopes that this new technology will meet or exceed the requirements met by previous manufacturing methods, as well as producing more cost effective, geometrically-complex products. This investigation evaluated the performance of 3D-printed aerospace test specimens made by Powder Bed Fusion Technologies, and compared them to forged specimens. A design of experiments varying build parameters was conducted in order to determine AM component porosity. Factors such as powder post-processing, directionality of the build, and fractology of the samples were evaluated through tensile strength testing and hardness testing of Inconel 718 wrought and EBM printed materials. Using electron microsopy, the responses to these factors were analyzed for stress fractures, grain boundaries, and other defects that occurred in the testing process. The comparison determined which metallurgical process provides the most effective material for aircraft usage.
ContributorsNez, Brittany Amber (Author) / Parsey, John (Thesis director) / Hsu, Keng (Committee member) / Godfrey, Donald (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / School of Earth and Space Exploration (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Radio astronomy is a subfield in astronomy that deals with objects emitting frequencies around 10 MHz to 100 GHz. The Low Frequency Array (LOFAR) is a array of radio antennas in Europe that can reach very low frequencies, roughly between 10-240 MHz. Our project was to image and clean a field from LOFAR. The data was a 10 degree square in the sky centered at a right ascension of 10:19:34.608 and a declination +49.36.52.482. It was observed for 600 seconds at 141 MHz. To clean the field, we had to flag and remove any stations that were not responding. Using a program called FACTOR, we cleaned the image and reduced the residuals. Next we checked the validity of our sources. We checked positional offsets for our sources using the TGSS survey at 150 MHz, and corrected the declination of our LOFAR sources by a factor of 0.0002 degrees. We also fixed the LOFAR fluxes by a factor of 1.15. After this systematic check, we calculated the spectral index of our sources using the FIRST survey at 1435 MHz. We plotted this spectral index against LOFAR flux as well as redshift of the sources, and compared these to literature.
ContributorsStawinski, Stephanie Mae (Author) / Scannapieco, Evan (Thesis director) / Windhorst, Rogier (Committee member) / Karen, Olsen (Committee member) / Department of Physics (Contributor) / School of International Letters and Cultures (Contributor) / School of Earth and Space Exploration (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Located in the Sunbelt of the Southwestern United States, Phoenix Arizona finds itself in one of the hottest, driest places in the world. Thankfully, Phoenix has the Salt River, Gila River, Verde River, and a vast aquifer to meet the water demands of the municipal, industrial, and agricultural sectors. However, rampant groundwater pumping and over-allocation of these water supplies based on unprecedented, high flows of the Colorado River have created challenges for water managers to ensure adequate water supply for the future. Combined with the current 17-year drought and the warming and drying projections of climate change, the future of water availability in Phoenix will depend on the strength of water management laws, educating the public, developing a strong sense of community, and using development to manage population and support sustainability. As the prevalence of agriculture declines in and around Phoenix, a substantial amount of water is saved. Instead of storing this saved water, Phoenix is using it to support further development. Despite uncertainty regarding the abundant and continuous availability of Phoenix's water resources, development has hardly slowed and barely shifted directions to support sustainability. Phoenix was made to grow until it legally cannot expand anymore. In order to develop solutions, we must first understand the push for development in water-stressed Phoenix, Arizona.
ContributorsVasquez, Brianna Nicole (Author) / Heimsath, Arjun (Thesis director) / Whipple, Kelin (Committee member) / School of Earth and Space Exploration (Contributor) / School of Art (Contributor) / School of Community Resources and Development (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
“Extremophile” is used to describe life that has adapted to extreme conditions and the conditions they live in are often used to understand the limits of life. In locations with low precipitation and high solar radiation, photosynthetic cyanobacteria can colonize the underside of quartz fragments, forming ‘hypoliths.’ The quartz provides protection against wind, reduces solar radiation, and slows the rate of evaporation following infrequent rain or fog events. In most desert systems, vascular plants are the main primary producers. However, hypoliths might play a key role in carbon fixation in hyperarid deserts that are mostly devoid of vegetation. I investigated hypolith distribution and carbon fixation at six sites along a rainfall and fog gradient in the central Namib Desert in Namibia. I used line point intersect transects to assess ground cover (bare soil, colonized quartz fragment, non-colonized quartz fragment, non-quartz rock, grass, or lichen) at each site. Additionally, at each site I selected 12 hypoliths and measured cyanobacteria colonization on quartz and measured CO2 flux of hypoliths at five of the six sites.
Ground cover was fairly similar among sites, with bare ground > non-colonized quartz fragments > colonized quartz fragments > non-quartz rocks. Grass was present only at the site with the highest mean annual precipitation (MAP) where it accounted for 1% of ground cover. Lichens were present only at the lowest MAP site, where they accounted for 30% of ground cover. The proportion of quartz fragments colonized generally increased with MAP, from 5.9% of soil covered by colonized hypoliths at the most costal (lowest MAP) site, to 18.7% at the most inland (highest MAP) site. There was CO2 uptake from most hypoliths measured, with net carbon uptake rates ranging from 0.3 to 6.4 μmol m-2 s-1 on well hydrated hypoliths. These carbon flux values are similar to previous work in the Mojave Desert. Our results suggest that hypoliths might play a key role in the fixation of organic carbon in hyperarid ecosystems where quartz fragments are abundant, with MAP constraining hypolith abundance. A better understanding of these extremophiles and the niche they fill could give an understanding of how microbial life might exist in extraterrestrial environments similar to hyperarid deserts.
Ground cover was fairly similar among sites, with bare ground > non-colonized quartz fragments > colonized quartz fragments > non-quartz rocks. Grass was present only at the site with the highest mean annual precipitation (MAP) where it accounted for 1% of ground cover. Lichens were present only at the lowest MAP site, where they accounted for 30% of ground cover. The proportion of quartz fragments colonized generally increased with MAP, from 5.9% of soil covered by colonized hypoliths at the most costal (lowest MAP) site, to 18.7% at the most inland (highest MAP) site. There was CO2 uptake from most hypoliths measured, with net carbon uptake rates ranging from 0.3 to 6.4 μmol m-2 s-1 on well hydrated hypoliths. These carbon flux values are similar to previous work in the Mojave Desert. Our results suggest that hypoliths might play a key role in the fixation of organic carbon in hyperarid ecosystems where quartz fragments are abundant, with MAP constraining hypolith abundance. A better understanding of these extremophiles and the niche they fill could give an understanding of how microbial life might exist in extraterrestrial environments similar to hyperarid deserts.
ContributorsMonus, Brittney Daniel (Author) / Throop, Heather (Thesis director) / Hall, Sharon (Committee member) / Cadillo-Quiroz, Hinsby (Committee member) / School of Life Sciences (Contributor) / School of Earth and Space Exploration (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Prior research has confirmed that supervised learning is an effective alternative to computationally costly numerical analysis. Motivated by NASA's use of abort scenario matrices to aid in mission operations and planning, this paper applies supervised learning to trajectory optimization in an effort to assess the accuracy of a less time-consuming method of producing the magnitude of delta-v vectors required to abort from various points along a Near Rectilinear Halo Orbit. Although the utility of the study is limited, the accuracy of the delta-v predictions made by a Gaussian regression model is fairly accurate after a relatively swift computation time, paving the way for more concentrated studies of this nature in the future.
ContributorsSmallwood, Sarah Lynn (Author) / Peet, Matthew (Thesis director) / Liu, Huan (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / School of Earth and Space Exploration (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Exoplanetary research is a key component in the search for life outside of Earth and the Solar System. It provides people with a sense of wonder about their role in the evolution of the Universe and helps scientists understand life's potential throughout a seemingly infinite number of unique exoplanetary environments. The purpose of this research project is to identify the most plausible biosignature gases that would indicate life's existence in the context of hyperarid exoplanetary atmospheres. This analysis first defines hyperarid environments based on known analogues for Earth and Mars and discusses the methods that researchers use to determine whether or not an exoplanet is hyperarid. It then identifies the most relevant biosignatures to focus on based on the scientific literature on analogous hyperarid environments and ranks them in order from greatest to least biological plausibility within extreme hyperarid conditions. The research found that methane (CH4) and nitrous oxide (N2O) are the most helpful biosignature gases for these particular exoplanetary scenarios based on reviews of the literature. The research also found that oxygen (O2), hydrogen sulfide (H2S) and ammonia (NH3) are the biosignatures with the least likely biological origin and the highest likelihood of false positive detection. This analysis also found that carbon dioxide (CO2) is a useful companion biosignature within these environments when paired with either CH4 or the pairing of hydrogen (H2) and carbon monoxide (CO). This information will provide a useful road map for dealing with the detection of biosignatures within hyperarid exoplanetary atmospheres during future astrobiology research missions.
ContributorsBrown, Kyle William (Author) / Cadillo-Quiroz, Hinsby (Thesis director) / Finn, Damien (Committee member) / Hartnett, Hilairy (Committee member) / School of International Letters and Cultures (Contributor) / School of Earth and Space Exploration (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
I test the hypothesis that galactic magnetic fields originate from regions of dense
star formation (Dahlem et al. 2006) by comparing maps of 120-240 MHz synchrotron emission and hydrogen alpha (Hα) emission of the tidally-interacting, edge-on, barred spiral galaxy UGC 9665. Synchrotron emission traces magnetic field strength to a rough first order, while Hα emission traces recent massive star formation. UGC 9665 was selected because it was included in the LOw Frequency ARray (LOFAR) TwoMetre Sky Survey (LoTSS; Shimwell et al. (2017)) as well as the Calar Alto Legacy Integral Field Area Survey (CALIFA; Sanchez et al. (2012)). I generated vertical intensity profiles at several distances along the disk from the galactic center for synchrotron emission and Hα in order to measure how the intensity of each falls off with distance from the midplane. In addition to correlating the vertical profiles to see if there is a relationship between star formation and magnetic field strength, I fit the LOFAR vertical profiles to characteristic Gaussian and exponential functions given by Dumke et al. (1995). Fitting these equations have been shown to be good indicators of the main mode of cosmic ray transport, whether it is advection (exponential fit) or diffusion (Gaussian fit) (Heesen et al. 2016). Cosmic rays originate from supernova,
and core collapse supernovae occur in star forming regions, which also produce
advective winds, so I test the correlation between star-forming regions and advective regions as predicted by the Heesen et al. (2016) method. Similar studies should be conducted on different galaxies in the future in order to further test these hypotheses and how well LOFAR and CALIFA complement each other, which will be made possible by the full release of the LOFAR Two-Metre Sky Survey (LoTSS) (Shimwell et al. 2017).
star formation (Dahlem et al. 2006) by comparing maps of 120-240 MHz synchrotron emission and hydrogen alpha (Hα) emission of the tidally-interacting, edge-on, barred spiral galaxy UGC 9665. Synchrotron emission traces magnetic field strength to a rough first order, while Hα emission traces recent massive star formation. UGC 9665 was selected because it was included in the LOw Frequency ARray (LOFAR) TwoMetre Sky Survey (LoTSS; Shimwell et al. (2017)) as well as the Calar Alto Legacy Integral Field Area Survey (CALIFA; Sanchez et al. (2012)). I generated vertical intensity profiles at several distances along the disk from the galactic center for synchrotron emission and Hα in order to measure how the intensity of each falls off with distance from the midplane. In addition to correlating the vertical profiles to see if there is a relationship between star formation and magnetic field strength, I fit the LOFAR vertical profiles to characteristic Gaussian and exponential functions given by Dumke et al. (1995). Fitting these equations have been shown to be good indicators of the main mode of cosmic ray transport, whether it is advection (exponential fit) or diffusion (Gaussian fit) (Heesen et al. 2016). Cosmic rays originate from supernova,
and core collapse supernovae occur in star forming regions, which also produce
advective winds, so I test the correlation between star-forming regions and advective regions as predicted by the Heesen et al. (2016) method. Similar studies should be conducted on different galaxies in the future in order to further test these hypotheses and how well LOFAR and CALIFA complement each other, which will be made possible by the full release of the LOFAR Two-Metre Sky Survey (LoTSS) (Shimwell et al. 2017).
ContributorsHuckabee, Gabriela R (Author) / Jansen, Rolf (Thesis director) / Windhorst, Rogier (Committee member) / Bowman, Judd (Committee member) / School of Earth and Space Exploration (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Both strong and weak gravitational lensing allow astronomers to calculate the mass distribution of the foreground lens by analysis of the distortion of the lensed light. This process is currently the most precise way to quantify the presence of dark matter in galaxies. In addition, strong gravitational lensing allows astronomers to observe directly the light from the background source, as it will be both magnified in brightness and easier to resolve. Current computer models can essentially "remove" the foreground galaxy/galaxies to isolate and reconstruct an image of the background source with a resolution greater than that observed without lensing. Both the measurement of dark matter within galaxies and the direct observation of lensed galaxies are goals for this project. This was done using LENSTOOL, a software package chosen for the project, and originally designed to perform such calculations efficiently. While neither goal was met in its entirety, this paper reflects the results of this project throughout the course of the past year.
ContributorsCompanik, Connor Matthew (Author) / Scowen, Paul (Thesis director) / Windhorst, Rogier (Committee member) / Jansen, Rolf (Committee member) / School of Earth and Space Exploration (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Accurate pointing is essential for any space mission with an imaging payload. The Phoenix Cubesat mission is being designed to take thermal images of major US cities from Low Earth Orbit in order to study the Urban Heat Island effect. Accurate pointing is vital to ensure mission success, so the satellite's Attitude Determination and Control System, or ADCS, must be properly tested and calibrated on the ground to ensure that it performs to its requirements. A commercial ADCS unit, the MAI-400, has been selected for this mission. The expected environmental disturbances must be characterized and modeled in order to inform planning the operations of this system. Appropriate control gains must also be selected to ensure the optimal satellite response. These gains are derived through a system model in Simulink and its response optimization tool, and these gains are then tested in a supplier provided Dynamic Simulator.
ContributorsWofford, Justin Michael (Author) / Bowman, Judd (Thesis director) / Jacobs, Daniel (Committee member) / School of Earth and Space Exploration (Contributor) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05