Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 66 for “"Craters"”.
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Impact Melt-Bearing Deposits Around Martian Craters
… impact melt emplacement around Martian craters. We compare our results to melt emplacement processes found on Venus, the Moon, and Mercury. We tentatively find Martian melt emplacement more closely resembles Venusian emplacement, rather than lunar emplacement. This suggests Martian melt …
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Finite-element modeling of large impact craters: Implications for the size of the Vredefort structure and the formation of multiple ring craters
… events. Most of the observations of impact craters created by such events are limited to remote sensing of their surface morphology; although there are large terrestrial craters whose sub-surface structures can be studied, most have been modified by subsequent geologic activity. Laboratory …
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Planetary mapping tools applied to floor-fractured craters on Mars
… I adapt automated tools for floor-fractured craters (FFCs) on Mars. These impact craters show a variety of surface features, occurring in different Martian environments, and having different fracturing origins. They provide a complex morphological and geological field of application. 433 FFCs …
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Impact induced porosity of terrestrial impact craters : a gravity study of Meteor Crater.
In this project we gathered and interpreted gravity anomaly data at Meteor Crater, and we used these data to constrain the porosity variations across Meteor Crater that were induced by the crater-forming impact event. We performed a gravity survey at the crater and merged these new data with legacy …
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Investigation of the depth and diameter of simple craters in the lunar mare
… (LOLA), the depths and diameters of 1429 simple craters in six different lunar maria units were measured, The analysis utilized a Graphical User Interface that was developed to access the LOLA data base and measure crater depth and diameter.The craters were compared to a published trend of …
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Deep Convolutional Neural Networks Based Single Image Super-Resolution And Classification For Crater Detection
Craters are among the most abundant features on the surface of many planets with great importance for planetary scientists. Craters reveal chronology information about planets and may be used for autonomous spacecraft navigation and landing. Typically, crater detection involves two main phases: (i) …
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Characterization of crater morphometry on the Moon and Mercury from altimetry observations
… are used to assess the morphometry of impact craters. Data acquired by the Mercury Laser Altimeter on the MESSENGER spacecraft are used to measure the depths and diameters of 537 craters at the high northern latitudes on Mercury, including 42 polar-deposit-hosting craters (PDCs) which host …
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Significance of Specific Force Models in Two Applications: Solar Sails to Sun-Earth L4/L5 and GRAIL Data Analysis Suggesting Lava Tubes and Buried Craters on the Moon
In the trajectory design process, gravitational interaction between the bodies of interest plays a key role in developing the over-arching force model. However, non-gravitational forces, such as solar radiation pressure (SRP), can significantly influence the motion of a spacecraft. Incorporating …
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Distal Flow Deposits: Exploring Impact Related Surface Flow Morphologies Beyond the Layered Ejecta Blankets of Mars
… current models suggest. Around just a few source craters, surface flow morphologies beyond the layered and often rugged-textured continuous ejecta blanket have been reported and have been suggested to result from an extended continuous ejecta unit. Despite the recent identification of such …
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Hydrocode modeling of oblique impacts into terrestrial planets
… point underneath the basin.</p> <p>Doublet craters form within crater rays on terrestrial bodies. The near simultaneous impact of two projectiles results in overlapping craters. This process results in modified crater morphologies and ejecta morphologies. I modeled the impact of two …
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Constraining the average fill densities of Mars' lowlands and fluvial erosion of Titan's polar regions.
… lowlands appear smooth because many of the craters in the north have been partially or completely buried beneath volcanic and sedimentary fill of unknown relative proportions. In Chapter 1, we use the Mars Orbiter Laser Altimeter (MOLA) topography data, the Mars Reconnaissance Orbiter (MRO) …
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The geophysical evolution of impact basins and volcanic structures on Mercury and the Moon
… volcanism. The forms that the resulting impact craters and volcanic structures take can tell us a great deal about the ways in which these processes occur and about the environment of the host body at the time of their formation. The surfaces of bodies like Mercury and the Moon are old, however, …
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Lunar orbiter state estimation using neural network-based crater detection
… network and image processing methods to detect craters from imagery taken by a spacecraft's on-board camera. These detections are matched with known lunar craters, and these matches can be used as features that are input to a extended Kalman filter. Our results show that, on average, LunaNet …
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Crater ice deposits near the south pole of Mars
… polar layered deposits (SPLD), dozens of impact craters contain large mounds of fill material with distinct similarities to the main layered deposits. Previously identified as outliers of the main SPLD, these deposits could offer clues to the climatic history of the Martian south polar region. We …
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3D GROUND-PENETRATING RADAR (GPR) INVESTIGATIONS: BURIED CULVERTS, HISTORICAL GRAVES, A SANDSTONE RESERVOIR ANALOG, AND AN IMPACT CRATER
… historical graves, reservoir analogs, and impact craters. In the first case of “buried culverts” I evaluated the GPR performance across five antenna frequencies to determine which would best image buried culverts. Laboratory measurements of soil were made to provide independent measurements to …
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Observational constraints on the number, albedos, size, and impact hazards of the near-Earth asteroids
… 47,000 +/- 6,000 years. The rate of formation of craters expected from the NEAs is found to be in close agreement with the observed number of craters on the Earth and Moon.
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The Mineralogy And Chemistry Of Micrometeorites
… selected on the basis that they contained impact craters (100-1000μm diameter) rather than larger impact holes (1-3mm diameter), as preliminary studies indicated that they were more likely to retain impact residues. These were subsequently analysed using digitised hack-scattered electron imaging, …
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Hydrostratigraphic units within the alluvium and tertiary volcanics of East Central Yucca Flat, Nevada Test Site
… test cavities, rubble chimneys and collapse craters collectively comprise a fourth hydrostratigraphic unit.
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Comparative Investigation of LIBS Spectra and Crater Morphology During Laser Ablation of Eutectic BiSn Alloys
… the morphology and elemental distribution of the craters, post ablation. The proposed approach was successfully applied and confirmed the influence of the aforementioned parameters on the stoichiometric transfer during the ablation process. It has been shown that ablation thresholds are affected …
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Micro Surface Texturing for Friction Control
… densities, are simulated and analysed. Circular craters of different sizes and densities, are fabricated using laser ablation on hardened tool steel samples, while the hexagonal dimples are fabricated using photo-lithography. The dimples are arranged in adjacent equilateral triangles layout. …
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