Theses and dissertations

This collection includes both ASU Theses and Dissertations, submitted by graduate students, and the Barrett, Honors College theses submitted by undergraduate students. 

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Modeling and Testing of a CubeSat Attitude Control System

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…

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

Cislunar Halo Orbits and Applications to FARSIDE Lunar Radio Telescope

Description

As part of NASA’s Artemis program, NASA intends to construct the Lunar Gateway space station in a near rectilinear halo orbit (NRHO) about the L2 Lagrange point of the Earth-Moon system in the near future. Gateway will help facilitate astronaut landings on the surface of the Moon and support numerous…

As part of NASA’s Artemis program, NASA intends to construct the Lunar Gateway space station in a near rectilinear halo orbit (NRHO) about the L2 Lagrange point of the Earth-Moon system in the near future. Gateway will help facilitate astronaut landings on the surface of the Moon and support numerous scientific endeavors. One of these scientific endeavors is FARSIDE. FARSIDE is a radio telescope array concept that will be deployed on the surface of the far side of the moon. Because of this, FARSIDE will require an orbiter, such as Gateway, to act as a communication relay to be able to communicate with ground stations on Earth. This thesis analyzes how the Lunar Gateway space station can assist FARSIDE with its communication with Earth and how unintentionally scattered radio signals from FARSIDE could affect the telescope’s astronomical observations. It provides insight into the optimal deployment latitude on the lunar surface for FARSIDE. The thesis first begins with a literature review of the circular restricted three body problem (CR3BP) and halo orbit calculations. This is followed by an analysis of an example halo orbit for the distance, elevation angle, and azimuth angle it has viewed from two possible sites for FARSIDE over one period of its trajectory. Using this same approach, an analysis of the Lunar Gateway’s NRHO trajectory over one year was performed along with an analysis of the scattered radio flux from ground stations on Earth and the flux leakage from Gateway. Three different possible deployment latitudes for FARSIDE were investigated: the equator, 30 degrees, and -30 degrees. The analysis in this thesis ultimately showed that a deployment latitude below the equator would be the preferable choice to maximize the visibility of Lunar Gateway from FARSIDE considering the geometry of the Lunar Gateway’s orbit.
ContributorsTrenter, Jake (Author) / Bowman, Judd (Thesis director) / Jacobs, Daniel (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor) / School of Earth and Space Exploration (Contributor)
Created2023-05
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Characterizing Low Frequency Delay Mode Contamination of the Hydrogen Epoch of Reionization Array

Description
The Hydrogen Epoch of Reionization Array, HERA, is a radio telescope currently being built in South Africa that plans to observe the early universe, specifically the earliest period of star and galaxy formation. It plans to use a tool called a delay spectrum to separate signal emitted from this time…

The Hydrogen Epoch of Reionization Array, HERA, is a radio telescope currently being built in South Africa that plans to observe the early universe, specifically the earliest period of star and galaxy formation. It plans to use a tool called a delay spectrum to separate signal emitted from this time from the much brighter radio foregrounds. It is the purpose of this paper to outline the method used to characterize the contamination of these delay spectra by bright emissions of radio here on Earth called radio frequency interference, RFI. The portion of the bandwidth containing the signal from the period of initial star formation was specifically examined. In order to receive usable data, the HERA commissioning team was assisted in the evaluation of the most recent data releases. On the first batch of usable data, flagging algorithms were run in order to mask all of the RFI present. A method of filling these masked values was determined, which allowed for the delay spectrum to be observed. Various methods of injecting RFI into the data were tested which portrayed the large dependence of the delay spectrum on its presence. Finally, the noise power was estimated in order to predict whether or not the limitations observed in the dynamic range were comparable to the noise floor. By examining the evolution of the delay spectrum's power as a range of noise power was introduced, there is a good amount of evidence that this limitation is in fact the noise floor. From this, we see that excision algorithms and interpolation used are capable of removing the effects of most all of the RFI contamination.
ContributorsBechtel, Shane Kirkpatrick (Author) / Bowman, Judd (Thesis director) / Jacobs, Daniel (Committee member) / Beardsley, Adam (Committee member) / School of Earth and Space Exploration (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05