Thesis (M.S.)--University of Hawaii at Manoa, 2006. / Includes bibliographical references (leaves xxxiii-xxxviii). / lv leaves, bound ill. 29 cm

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abstract: Previous workers hypothesized that lunar Localized Pyroclastic Deposits (LPDs) represent products of vulcanian-style eruptions, since some have low proportions of juvenile material. The objective of the first study is to determine how juvenile composition, calculated using deposit and vent volumes, varies among LPDs. I used Lunar Reconnaissance Orbiter Camera Narrow Angle Camera (LROC NAC) digital terrain models (DTMs) to generate models of pre-eruption surfaces for 23 LPDs and subtracted them from the NAC DTMs to calculate deposit and vent volumes. Results show that LPDs have a wide range of juvenile compositions and thinning profiles, and that there is a positive relationship between juvenile material proportion and deposit size. These findings indicate there is greater diversity among LPDs than previously understood, and that a simple vulcanian eruption model may only apply to the smallest deposits. There is consensus that martian outflow channels were formed by catastrophic flooding events, yet many of these channels exhibit lava flow features issuing from the same source as the eroded channels, leading some authors to suggest that lava may have served as their sole agent of erosion. This debate is addressed in two studies that use Context Camera images for photogeologic analysis, geomorphic mapping, and cratering statistics: (1) A study of Mangala Valles showing that it underwent at least two episodes of fluvial activity and at least three episodes of volcanic activity during the Late Amazonian, consistent with alternating episodes of flooding and volcanism. (2) A study of Maja Valles finds that it is thinly draped in lava flows sourced from Lunae Planum to the west, rendering it analogous to the lava-coated Elysium outflow systems. However, the source of eroded channels in Maja Valles is not the source of the its lava flows, which instead issue from south Lunae Planum. The failure of these lava flows to generate any major channels along their path suggests that the channels of Maja Valles are not lava-eroded. Finally, I describe a method of locating sharp edges in out-of-focus images for application to automated trajectory control systems that use images from fixed-focus cameras to determine proximity to a target. / Dissertation/Thesis / Doctoral Dissertation Geological Sciences 2018

Thesis--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (p.133-142)

Thesis (Ph. D.) -- University of Tennessee, Knoxville, 2005. / Vita. Includes bibliographical references (p. 57-76). Also available via World Wide Web.

Dreibus and Wänke (1985) calculated a bulk composition for the interior of Mars (DW model) based on eight Martian meteorites. Since then, experiments on the Martian interior have used this model, or similar models, to understand processes that may influence basalt genesis within the Martian mantle. Recent experiments have shown that the DW model does not fit with the current, now greater number of Martian meteorites (132 including paired stones as of April 2014) and surface basalt compositions. One of the parameters that does not match is the Mg # (atomic [Mg2+/(Mg2+ + Fe2+)]*100); the current data show that Mars is not as iron rich as once thought and needs a higher bulk Mg # for the mantle to produce Martian basaltic compositions. This project involves experiments using a new bulk composition with an Mg # of 80 to update the compositions of a partially melted Martian mantle. A melt produced by this new bulk composition consists of MgO and FeO levels that match well with the primitive Martian meteorite Yamato-980459. Additionally, this composition was produced with 37% melt. Melts produced with this bulk composition match poorly with Na2O composition of Martian meteorites and match better, but still not particularly well, with CaO and Al2O3 compositions. However, lower-temperature partial melts of the Mg # 80 mantle match well with CaO, Al2O3, FeO, and Na2O compositions of Martian surface basalts. This shows that the source of the surface basalts is represented well by the model in this study.

The most widely used and accepted composition for the Martian mantle in experimental petrology is the Dreibus and Wänke (1985) proposed composition based on only eight SNC meteorites. This composition is enriched in iron with respect to the Earth, which follows what we see from samples of Mars. The magnesium number (Mg#=Mg/Mg+Fe) of the Dreibus and Wänke (1985) composition is Mg#75, which is iron rich compared to Earth’s Mg# of around 90. However, when experimentally melted as a source for generating Martian basalts, the melt concentrates iron further, higher than the Mars basalt compositions, and requires melting a large percentage of the mantle to reach a composition that is comparable to known Martian basalts. Partial melting experiments of an Mg# 80 mantle composition produced shergottite-like melts with a lower percentage of partial melting than with the Mg#75 compositions. This would be more likely since the Martian mantle would have cooled considerably by the time it would have produced the shergottites, which was only approximately 180 million years ago. The reprised composition is Mg#80 and less iron rich than the DW composition, but more iron-rich than Earth.

As part of the ExoMars space programme, the 2016 Trace Gas Orbiter mission was announced. The Martian Atmospheric Trace Molecule Occultation Spectrometer (MATMOS) was a proposed Fourier transform spectrometer and solar imager concept pair that would provide for trace gas detection and aerosol observation of the Martian atmosphere. Martian aerosols – namely CO2 crystals, water-ice crystals, and dust – have been observed during past missions; however, observations have failed to fully characterize their physical and optical properties. This thesis presents an analysis of the ability of the proposed imager to determine the pointing of the spacecraft independent of the spectrometer. Furthermore, proof of concept is presenting showing the ability to, in laboratory conditions, characterize the precision and stability of the imager. Finally, window regions in the transmittance spectrum of the Martian atmosphere are determined simulating the Martian atmosphere and viewing geometry.

Phyllosilicates are widespread on Noachian to Early Hesperian terrains on Mars and can help constrain the planet’s geologic and environmental history, particularly its aqueous and redox history, which in turn can provide clues about past habitability. A range of ferrous and mixed-valence smectites were synthesized and then exposed to varying O2 fluxes under dry conditions to determine if Fe/Mg trioctahedral smectites can be oxidized without an aqueous medium to form dioctahedral smectites like those observed on the surface of Mars. The appearance of a secondary peak in some unaltered samples indicates a separate phase formed during synthesis, which remained throughout the oxidation process. Partial oxidation was achieved by all samples, but only those with the highest starting Fe3+ content reached almost complete oxidation. Rapid initial oxidation was observed for all samples, but seemed to subside before oxidation was complete, indicating the process becomes unfavorable after a certain point. All three O2 fluxes used in this study were successful in partially oxidizing the smectite samples but no correlation was observed between O2 flux and actual amount of oxidation, i.e., a higher O2 flux does not necessarily result in higher production of ferric iron. The process of oxidation did cause octahedral sheet contraction in some cases; however, in some samples octahedral sheet expansion was observed with oxidation. No additional phases were formed upon oxidation and no Fe ejection was observed. Overall, the amount of oxidation observed for all samples indicates that O2 alteration of trioctahedral smectites into dioctahedral smectites can proceed under dry conditions, meaning oxidation could have continued on Mars after surface water dried up. / Geology

Over the past decade, there has been a considerable increase in space exploration efforts, driving the need for new methods to examine planets and other celestial bodies. The current trend involves designing spacecraft capable of surveying surfaces from elevated positions, with drones proving to be more suited for the task. . The focus of space missions has primarily been on exploring Mars, as evidenced by the pioneering flight of the Ingenuity helicopter in 2021. The Martian environment poses significant aerodynamic challenges due to its thin atmosphere and low pressure, complicating drone flight. The generation of lift is problematic owing to the scant atmosphere and the restricted dimensions required for space missions, resulting in low-chord Reynolds number flows. Despite the reduction in skin friction drag due to lower viscosity, the decrease in airfoil efficiency is significantly compromised, with only a partial counterbalance by the reduced gravitational pull. Two main challenges must be addressed: low chord-based Reynolds number flows and Martian dust. The former results in the formation of Laminar Separation Bubbles (LSB), severely impairing the aerodynamic efficiency of the airfoil. Concurrently, the accumulation of dust particles on the airfoil’s surface significantly affects its performance, altering its geometry and surface roughness. Thus, it is crucial to accurately determine the presence and location of both separation bubbles and particle deposition to predict performance degradation. \\This thesis presents a comprehensive survey on drones for planetary exploration and an analysis conducted on a cambered plate with 6$\%$ camber and 1$\%$ thickness, ideal for the types of flows considered. The studies are carried out for Reynolds number flows, namely 20,000 and 50,000, to observe the effects of rotor and airfoil dimensions. The computational study is performed using ANSYS Fluent, utilising a two-dimensional CFD model with a C-type mesh and the gamma-Re ($\gamma-Re_{\theta}$) transition model, which aids in capturing the behaviour of these flow regimes. Additionally, for the dust study, two phases are created: a primary phase, the atmosphere, and a secondary phase, the dust particles. The volume fraction of particles is assumed to be small enough to imply that the primary phase influences the secondary, but not vice versa (one-way coupling). To assess particle adhesion, a deposition model has been developed to check for the deposition of dust particles, working in conjunction with the Discrete Phase Modelling (DPM), which simulates the trajectory of particles within the control volume. The deposition model comprises a particle transport model, which accounts for the forces acting on the particles, and a particle-wall interaction model, which determines the particles' rebound or adhesion. The results are presented and discussed at the end of the thesis, along with a brief discussion of future studies focusing on alternative assumptions for dust modelling.