Matching Items (68)
Description
Solar system orbital dynamics can offer unique challenges. Impacts of interplanetary dust particles can significantly alter the surfaces of icy satellites and minor planets. Impact heating from these particles can anneal away radiation damage to the crystalline structure of surface water ice. This effect is enhanced by gravitational focusing for giant planet satellites. In addition, impacts of interplanetary dust particles on the small satellites of the Pluto system can eject into the system significant amounts of secondary intra-satellite dust. This dust is primarily swept up by Pluto and Charon, and could explain the observed albedo features on Pluto's surface. In addition to Pluto, a large fraction of trans-neptunian objects (TNOs) are binary or multiple systems. The mutual orbits of these TNO binaries can range from very wide (periods of several years) to near-contact systems (less than a day period). No single formation mechanism can explain this distribution. However, if the systems generally formed wide, a combination of solar and body tides (commonly called Kozai Cycles-Tidal Friction, KCTF) can cause most systems to tighten sufficiently to explain the observed distributions. This KCTF process can also be used to describe the orbital evolution of a terrestrial-class exoplanet after being captured as a satellite of a habitable-zone giant exoplanet. The resulting exomoon would be both potentially habitable and potenially detectable in the full Kepler data set.
ContributorsPorter, Simon Bernard (Author) / Desch, Steven (Thesis advisor) / Zolotov, Mikhail (Committee member) / Timmes, Francis (Committee member) / Scannapieco, Evan (Committee member) / Robinson, Mark (Committee member) / Arizona State University (Publisher)
Created2013
Description
A robotic exploration mission that would enter a lunar pit to characterize the environment is described. A hopping mechanism for the robot's mobility is proposed. Various methods of hopping drawn from research literature are discussed in detail. The feasibilities of mechanical, electric, fluid, and combustive methods are analyzed. Computer simulations show the mitigation of the risk of complex autonomous navigation systems. A mechanical hopping mechanism is designed to hop in Earth gravity and carry a payload half its mass. A physical experiment is completed and proves a need for further refinement of the prototype design. Future work is suggested to continue exploring hopping as a mobility method for the lunar robot.
ContributorsMcKinney, Tyler James (Author) / Thangavelautham, Jekan (Thesis director) / Robinson, Mark (Committee member) / Asphaug, Erik (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2015-05
Description
Neutron spectroscopy is used to determine bulk water abundances in the near surface of planetary bodies. The Dynamic Albedo of Neutrons (DAN) instrument on the Mars Science Laboratory (MSL) rover, Curiosity, is able to determine the depth distribution of water and neutron absorbers in the top ~50 cm of the subsurface. In this dissertation, I focus on answering significant geologic questions by interpreting DAN results in the geologic context provided by other MSL and orbital datasets. This approach enabled me to investigate significant outstanding questions in Gale crater geology, with implications for the evolution and habitability of Mars.I mapped an extensive silicic volcaniclastic layer in the subsurface, the first identified and mapped on Mars. This layer served as a silica source for other silica-rich features. But unlike those features, this layer contains abundant rhyolitic glass, indicating an evolved volcanic origin. Similar material on Earth is produced by plate tectonics, so this layer has important implications for the evolution of Mars, which has no evidence of plate tectonics.
One of the primary motivations for exploring Gale crater is a distinct clay mineral signature from orbital data of the Compact Reconnaissance Imaging Spectrometer at Mars (CRISM), which has also identified a corresponding hydration signature. I compared DAN and CRISM hydration results and found that CRISM hydration results are biased by the presence of regolith, indicating that this regolith is either more hydrated or has a different grain size texture than bedrock.
Clay minerals are primary binding sites for organics on Earth, and most organic-mineral binding mechanisms involve either water or hydroxyl. This makes hydrated clays the most efficient hosts for organic preservation, but clays are normally dehydrated when measured by MSL. However, my DAN-derived water abundances are greater in the most clay-rich unit of Gale crater, suggesting that clay minerals may be hydrated in the subsurface. I developed a new amorphous component analysis method that simultaneously constrains clay mineral hydration and abundances of various hydrated amorphous phases. I found a strong correlation between “excess” water and smectites (expandable clay minerals), indicating that these clay minerals are hydrated in the subsurface.
ContributorsCzarnecki, Sean (Author) / Hardgrove, Craig (Thesis advisor) / Robinson, Mark (Committee member) / Ruff, Steve (Committee member) / Bell, Jim (Committee member) / Gasda, Patrick (Committee member) / Arizona State University (Publisher)
Created2023
ContributorsCherland, Carl (Performer) / Fuller, Charles L. (Performer) / O'Brien, Robert (Performer) / Hooper, Wm. John (Performer) / Graduate Chorale (Performer) / Recital Chorale (Performer) / ASU Library. Music Library (Publisher)
Created1987-10-01
ContributorsEngelson, Thea Sikora (Performer) / Kelly, Kathleen (Performer) / Engelson, Robert (Performer) / Weber, Steven (Performer) / LaFave, Alan (Performer) / ASU Library. Music Library (Publisher)
Created1989-06-29
ContributorsYom, Chin-Seup (Performer) / Wagner, Mary Purcell (Performer) / Nicholas, Cynthia (Performer) / Hloucal, Amy (Performer) / Bartschi, Kenneth (Performer) / Wicks, Stanley M. (Performer) / Willis, Dawn O. (Performer) / Graduate Chorale (Performer) / Recital Chorale (Performer) / ASU Library. Music Library (Publisher)
Created1987-11-12
ContributorsGreen, Stephen J. (Performer) / Biffle, George (Performer) / Meredith, Steven (Performer) / Fuller, Charles L. (Performer) / Shryock, Darin W. (Performer) / Kelly, Kathleen (Performer) / Graduate Chorale (Performer) / Recital Chorale (Performer) / ASU Library. Music Library (Publisher)
Created1988-11-17
ContributorsKlevberg, Janet (Performer) / Krabbe, Tom (Performer) / Peterson, Craig C. (Performer) / Staininger, Lynn (Performer) / Woodrow, Marie (Performer) / Graduate Chorale (Performer) / Recital Chorale (Performer) / ASU Library. Music Library (Publisher)
Created1990-10-11
ContributorsWiest-Parthun, Karen (Performer) / Roueche, Michelle (Performer) / Rinsema, Joel M (Performer) / Davis, Cheryl (Performer) / Priddy, S. Bryan (Performer) / Recital Chorale (Performer) / Graduate Chorale (Performer) / ASU Library. Music Library (Publisher)
Created1993-12-02
ContributorsLarson, Brook (Conductor) / Smit, Ryan (Conductor) / Wright, Alicia (Conductor) / McCreary, Kimilee D. (Conductor) / Larson, Matthew (Performer) / Ortman, Mory (Performer) / Graduate Chorale (Performer) / Recital Chorale (Performer) / ASU Library. Music Library (Publisher)
Created2000-04-27