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Alluvial deposits within Martian impact craters are sensitive morphologic records of modification by liquid water, and can help constrain past climate conditions. This study explores the evolution of Late Hesperian-Amazonian-age sedimentary deposits within two craters, Mojave and Eberswalde. For Mojave crater, the evolution of intracrater alluvial fan systems and the climatic context are poorly understood. Analysis of stratigraphic relationships between the fans and crater infill suggests that precipitation which formed the systems was temporally closely associated with the impact process. Regional mapping of youthful fluvial features within a ~300 km radius of Mojave supports a genetic link between the impact event and precipitation, due to dense clustering around the crater. Analysis of five additional Late Hesperian-Amazonian craters, which also contain evidence for catchment-fan formation by precipitation, shows similar clustering of fluvial activity. Two mechanisms of water production are suggested to have formed the features observed: (a) localised impact-induced precipitation due to impact plume-related atmospheric effects, and (b) a regional snowpack which melted locally due to impact-induced heating. Eberswalde crater contains multiple sedimentary systems sourced from channels which breach the crater rim, and the depositional system as a whole is poorly understood. Mapping of rocks with differing characteristics within the second largest depositional system, and reconstruction of stratigraphic architecture, shows that the deposit records backstepping of putative deltaic lobe sedimentary bodies. The observed sedimentary architecture is best explained by a net transgression, likely caused by lake level rise through time. This behaviour is not recorded within the best-studied and largest Eberswalde deposit likely due to subsequent burial by progradational lobes. In addition, planform evolution of sinuous channels within the largest Eberswalde deposit is investigated, and mapped chute cutoffs are suggested as implying that overbank flooding occurred.

The Planetary And Natural scene Generation Utility (P ANGU) , developed at the University of Dundee for the European Space Agency (ESA), successfully generates stochastic Digital Elevation Models (DEMs) of simulated planetary surfaces. P ANGU was developed to allow development and extensive testing of vision-guided navigation software for autonomous planetary landers. PANGU's initial scope was to model airless bodies such as the Moon and Mercury. ESA has outlined the Mars exploration programme for the next few decades as part of its Aurora programme. In this context, "Modelling Martian Geomorphology" looks at extending PANGU's capabilities to allow the modelling of Martian surfaces. A review of available Martian remote sensing data is undertaken and a summary of Martian terrain types is provided. From this, the requirements for a Martian surface model are derived. The development of a stochastic sand dune model was identified as a key addition to allow P ANGU to model Mars. Existing geomorphological sand dune models concentrate on modelling the dynamic processes that generate sand dunes. A dynamic model developed by Werner is implemented in PANGU. Novel aspects of this research are, running the model over existing surfaces and exploration of scale factors for use in a P ANGU hierarchical model. The model though proves to be scale dependent and is not directly suitable for use in PANGU. Research is undertaken into feature extraction from the dynamic model. Dune crests and toe locations are extracted and a geometric model of the dune cross-section is used to reconstruct the dune. This generates a model that can be rendered at a range of scales as required by PANGU. This model suffers from artefacts introduced in the dune reconstruction where dunes overlap. An entirely static model is developed based on the random placement of barchan dunes. Where these overlap, they are merged to produce barchanoid ridge dunes. With high densities of initial barchan dunes, after merging, transverse dune fields are created. This method has been implemented in P ANGU and used in development research by ESA.

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Prior to their retrieval from low Earth orbit (LEO), the individual solar cells that make up the 'V2' solar array panel from the Huhble Space Telescope (HST) were prone to hypervelocity (>5 km/s ) impact damage from micrometeoroids and space debris. The analysis of such passive collector surfaces allows sampling of micrometeoroids that have not undergone any terrestrial atmospheric alteration and better defines the population of space debris particles below the lmm size range. Herein a new approach has been taken to try and identify the nature atid origin of impact derived residues generated in the individual solar cells from the HST. A total of 25 solar cells were selected on the basis that they contained impact craters (100-1000?n 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, coupled with digitised x-ray elemental mapping and micro-spot analysis to locate, identify and classify the residues. 29 impact craters were located on solar cells. In the analysis of the residues; 3 were identified residues as space debris in origin, 6 unclassified and 20 as micrometeoroid. The space debris derived residues were identified as remnants of a paint fragment, a stainless steel particle and a fragment of a printed circuit board. The micrometeoroid derived residues were sub-classified in terms of mineral chemistry, with apparent mafic- and phyllo- silicates being the dominant components, with minor iron-nickel metal and iron sulfides, suggesting a broadly chondritic origin. Fe-Ni rich residue was also identified that would appear to belong to a group of non-chondritic particles previously unrecognised. Possible refractory or Ca/Al rich inclusions from a primitive micrometeoroid were also observed as near intact Ca-rich fragments, the textures of the individual grains suggested that they were not merely terrestrial contamination. Laboratory impact studies, using a light-gas-gun to accelerate small fragments (125- 250?m) of known meteorite mineralogies up to 5km/s, and then impact them into solar cells have generated a suite of residues that are analogues of those observed from LEO studies. The silicate minerals generated residues that were intimately associated with the host melt glass. Metallic sulfides and metals generated surface and sub-surface immiscible droplets. Several craters also contained near-intact fragments of minerals. Overall. despite the small sample set examined. the observed dominance of micrometeoroid to space debris residue chemistry (correlating to particle size range of 8-80 ?m) corresponds well to the accepted flux models.

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No description available.