Model Age Derivation of Large Martian Impact Craters, Using Automatic Crater Counting Methods

Determining when an impact crater formed is a complex and tedious task. However, this knowledge is crucial to understanding the geological history of planetary bodies and, more specifically, gives information on erosion rate measurements, meteorite ejection location, impact flux evolution and the loss of a magnetic field. The derivation of an individual crater's age is currently performed through manual counting. Because crater size scales as a power law, this method is limited to small (and/or young) surface areas and, in the case of the derivation of crater emplacement age, to a small set of impact craters. Here, we used a Crater Detection Algorithm, specifically retrained to detect small impact craters on large‐ and high‐resolution imagery data set to solve this issue. We applied it to a global, 5 m/pixel resolution mosaic of Mars. Here, we test the use of this data set to date 10 large impact craters. We developed a cluster analysis tool in order to distinguish potential secondary crater clusters from the primary crater population. We then use this, filtered, crater population to date each large impact crater and evaluate our results against literature ages. We found that automated counting filtered through clustering analysis produced similar model ages to manual counts. This technique can now be expanded to much wider crater dating surveys, and by extension to any other kind of Martian surface. We anticipate that this new tool will considerably expand our knowledge of the geological events that have shaped the surface of Mars, their timing and duration

Geologic Setting of the Phoenix Lander Mission Landing Site

The Phoenix Lander touched down on the northern distal flank of the shield volcano Alba Patera in a ~150 km wide valley underlain by the Scandia Formation. The geomorphology and geology of the landing site is dominated by the ~0.6 Ga, 11.5 km wide, bowl-shaped impact crater, Heimdal, and its areally extensive ejecta deposits. The Lander is located ~20 km to the west of the crater and is sitting on a plains surface underlain by partially eroded Heimdal ejecta deposits. Heimdal was produced by a hypervelocity impact into fine-grained, ice-rich material and is inferred to have produced high velocity winds and a ground-hugging ejecta emplacement mode that destroyed or buried preexisting surfaces and rock fields out to ~10 crater radii. Patterned ground is ubiquitous, with complex polygon patterns and rock rubble piles located on older plains: ~3.3 Ga) to the west of the ejecta deposits. Crater size frequency distributions are complex and represent equilibria between crater production and destruction processes: e.g., aeolian infill, cryoturbation, relaxation of icy substrate). Rock abundances increase near craters for the older plains and rocks with their dark shadows explain the reason for the few percent lower albedo for these plains as opposed to the Heimdal ejecta deposits. Many rocks at the landing site have been reworked by cryoturbation and moved to polygon troughs. The evidence for cryoturbation and the lack of aeolian features imply that the soils sampled by Phoenix are locally derived and mixed with a subordinate amount of wind-blown dust

Remote Sensing of World War II Era Unexploded Bombs Using Object-Based Image Analysis and Multi-Temporal Datasets: A Case Study of the Fort Myers Bombing and Gunnery Range

During World War II, United States Army and Navy pilots trained on several hundred bombing ranges encompassing more than 12 million acres of land, leaving behind crater-scarred landscapes across the country. Post-war estimates suggest that 10-15% of aerial bombs used failed to detonate as intended, so these areas today are contaminated by a large number of dangerous unexploded bombs (UXB) which remain under the surface. Until recently, detecting UXB has been a tedious and expensive process done in three stages: (1) identifying and mapping general areas of concentrated bomb craters using historical air photos and records; (2) intensely searching these areas at a larger scale for much smaller UXB entry holes; and (3) confirming the presence of individual UXB using magnetometry or ground-penetrating radar. This research aims to streamline the workflow for stage 1 and 2 using semi-automated object-based image analysis (OBIA) methods with multi-source high spatial-resolution imagery. Using the Fort Myers Bombing and Gunnery Range in Florida as a study area, this thesis determines what OBIA software and Imagery is best at locating UXB in this environment. I assess the use of LiDAR-derived DEMs, historical air photos and high-resolution color digital orthophotos in Feature Analyst and Imagine Objective, and discuss optimal inputs and configurations for UXB searches in karst wetlands. This methodology might be applied by the detection and clearance industry in former war zones, and aid in restoring former training ranges to safe land uses in the U.S

Abstracts of the Annual Meeting of Planetary Geologic Mappers, Flagstaff, AZ, 2008

Topics discussed include: Merging of the USGS Atlas of Mercury 1:5,000,000 Geologic Series; Geologic Mapping of the V-36 Thetis Regio Quadrangle: 2008 Progress Report; Structural Maps of the V-17 Beta Regio Quadrangle, Venus; Geologic Mapping of Isabella Quadrangle (V-50) and Helen Planitia, Venus; Renewed Mapping of the Nepthys Mons Quadrangle (V-54), Venus; Mapping the Sedna-Lavinia Region of Venus; Geologic Mapping of the Guinevere Planitia Quadrangle of Venus; Geological Mapping of Fortuna Tessera (V-2): Venus and Earth's Archean Process Comparisons; Geological Mapping of the North Polar Region of Venus (V-1 Snegurochka Planitia): Significant Problems and Comparisons to the Earth's Archean; Venus Quadrangle Geological Mapping: Use of Geoscience Data Visualization Systems in Mapping and Training; Geologic Map of the V-1 Snegurochka Planitia Quadrangle: Progress Report; The Fredegonde (V-57) Quadrangle, Venus: Characterization of the Venus Midlands; Formation and Evolution of Lakshmi Planum (V-7), Venus: Assessment of Models using Observations from Geological Mapping; Geologic Map of the Meskhent Tessera Quadrangle (V-3), Venus: Evidence for Early Formation and Preservation of Regional Topography; Geological Mapping of the Lada Terra (V-56) Quadrangle, Venus: A Progress Report; Geology of the Lachesis Tessera Quadrangle (V-18), Venus; Geologic Mapping of the Juno Chasma Quadrangle, Venus: Establishing the Relation Between Rifting and Volcanism; Geologic Mapping of V-19, V-28, and V-53; Lunar Geologic Mapping Program: 2008 Update; Geologic Mapping of the Marius Quadrangle, the Moon; Geologic Mapping along the Arabia Terra Dichotomy Boundary: Mawrth Vallis and Nili Fossae, Mars: Introductory Report; New Geologic Map of the Argyre Region of Mars; Geologic Evolution of the Martian Highlands: MTMs -20002, -20007, -25002, and -25007; Mapping Hesperia Planum, Mars; Geologic Mapping of the Meridiani Region, Mars; Geology of Holden Crater and the Holden and Ladon Multi-Ring Impact Basins, Margaritifer Terra, Mars; Geologic Mapping of Athabasca Valles; Geologic Mapping of MTM -30247, -35247 and -40247 Quadrangles, Reull Vallis Region of Mars; Geologic Mapping of the Martian Impact Crater Tooting; Geology of the Southern Utopia Planitia Highland-Lowland Boundary Plain: First Year Results and Second Year Plan; Mars Global Geologic Mapping: Amazonian Results; Recent Geologic Mapping Results for the Polar Regions of Mars; Geologic Mapping of the Medusae Fossae Formation on Mars (MC-8 SE and MC-23 NW) and the Northern Lowlands of Venus (V-16 and V-15); Geologic Mapping of the Zal, Hi'iaka, and Shamshu Regions of Io; Global Geologic Map of Europa; Material Units, Structures/Landforms, and Stratigraphy for the Global Geologic Map of Ganymede (1:15M); and Global Geologic Mapping of Io: Preliminary Results

A Comparison of Relict and Active Terrestrial Patterned Ground as an Analog for Mars

Patterned ground is a ubiquitous landform in periglacial regions of Earth and is also present across the mid to high latitudes of Mars. The association of terrestrial patterned ground to the presence of subsurface water ice in the form of permafrost that develops a seasonal ‘wet’ active layer during the summer thaw prompted further investigation of patterned ground on Mars. The Phoenix spacecraft was sent to the surface of the north polar plains of Mars to investigate an area of patterned ground where water ice was predicted to occur. The confirmation of subsurface water ice at the Phoenix landing site confirmed the hypothesis that water ice and patterned ground on Mars are intricately linked, however outstanding questions remain regarding the mode of formation of martian patterned ground. Dry modification via sublimation and thermal-driven processes are possible under present-day climate conditions, however warmer climate conditions are predicted to have occurred during past periods of high obliquity and could have supported periglacial freeze-thaw modification of patterned ground on Mars. Understanding the extent to which liquid water may have been available in the recent geological history of Mars is important to constraining past habitability as well as identifying resources for future long-duration human exploration. It is suggested that if patterned ground on Mars experienced periglacial modification in the past, then it currently exists in a relict form. This research examines the morphometry and surface roughness parameters of active and relict terrestrial patterned ground sites in conjunction with evaluations of martian patterned ground to identify parameters that may assist with ongoing efforts to determine the age and modes of historical modification of patterned ground on Mars

Subsurface Reflectors Detected by SHARAD Reveal Stratigraphy and Buried Channels over Central Elysium Planitia, Mars

The Central Elysium Planitia (CEP) is one of the youngest geological units on Mars and displays evidence of volcanic and fluvial activities on the surface. The origin of the CEP material has long been debated with a range of hypotheses from purely fluvial to solely volcanic origins. This study presents a comprehensive investigation of SHARAD (SHAllow RADar) data to reveal subsurface radar reflectors over the CEP region. Distribution of the detected radar reflectors show possible connections between the CEP and outflow channels, such as Athabasca Valles and Marte Vallis. Analysis of the radar reflectors in the CEP region show six subsurface layers implying multiple depositional and erosional episodes. Two of the layers are found to correspond to two exposed layers of one terraced crater. By measuring the depth accurately of these exposed layers in the derived HiRISE (High Resolution Imaging Scientific Experiment) and CTX (Context Camera) DTMs (Digital Terrain Models) and inverting the dielectric constant combining the layers in radargrams, an interpretation that the filling material contains water ice is favoured

Progress and prospects for research on Martian topographic features and typical landform identification

The study of Martian surface topography is important for understanding the geological evolution of Mars and revealing the spatial differentiation of the Martian landscape. Identifying typical landform units is a fundamental task when studying the origin and evolution of Mars and provides important information for landing on and exploring Mars, as well as estimating the age of the Martian surface and inferring the evolution of the Earth’s environment. In this paper, we first investigate Mars exploration, data acquisition and mapping, and the classification methods of Martian landforms. Then, the identification of several typical Martian landform types, such as aeolian landforms, fluvial landforms, and impact landforms, is shown in detail. Finally, the prospects of Mars data acquisition, landform mapping, and the construction and identification of the Martian landform classification system are presented. The construction of the Martian landform classification system and the identification of typical Martian landforms using deep learning are important development directions in planetary science

Mapping the Martian Geologic Record: Studies of the Gusev Crater Spirit Landing Site and Plagioclase Feldspar Compositions on Mars

The flurry of activity involved in the scientific study of Mars has resulted in multiple new data sets from several missions (Mars Global Surveyor (MGS), Mars Odyssey (MO), Mars Exploration Rovers (MER), Mars Reconnaissance Orbiter (MRO), and Mars Express) that provide information for unlocking the planet’s geologic and climatic history. This three part study utilized both orbital data and laboratory experiments to examine Mars for morphologic and mineralogic evidence of aqueous activity and magmatic evolution. The first study examined Gusev Crater, landing site for the Spirit MER rover. This work began during final landing site selection and was published just prior to Spirit’s January 2004 landing. In this work, I examined the paradigm that Gusev once held a paleolake and that it contains detrital sediment from the northern highlands. Analyses involved using the most current data then available. I produced thermophysical, morphological, and surface unit maps showing the spatial distribution and stratigraphic relationships of materials on the floor of Gusev. Orbital analyses found no unambiguous evidence of paleolake deposits. This study offered alternative hypotheses explaining floor units, one of which, volcanic deposition, has since been verified by Spirit on the ground. The second and third studies address our ability to accurately derive plagioclase compositions on Mars and to use thermal emission spectroscopy to map vii the distribution of plagioclase compositions on Mars. Plagioclase is the most abundant mineral in the martian crust and may provide information about the igneous evolution and subsequent alteration of the Martian surface. The second study focuses on mixtures more complex in nature than the two-component (composition) plagioclase sand mixtures used in previous work. Linear deconvolutions of laboratory spectra from mixtures involving additional components and phases were used to calculate average plagioclase compositions whose accuracies were found to be comparable to previous studies. The final project carried results from previous laboratory studies one step further to map the global distribution of plagioclase compositions on Mars. Maps reveal a world dominated by labradorite and bytownite, with lesser amounts of other plagioclase. Localized variations are difficult to discern at the scale of individual MGS Thermal Emission Spectrometer (TES) observations