The lunar regolith is sensitive to the bombardment history of the Moon and contains a wealth of knowledge regarding the types of processes that have modified the lunar crust through time. Noble gases that are produced and trapped in the lunar regolith, as a result of this interaction with the space environment, can be used to determine the cosmic ray exposure age, maturity, shielding depth and antiquity age of lunar regolith samples. This thesis aims to probe this temporal archive to further understand the impact history of the Moon contained within the regolith. Initially, all the published noble gas literature data for the Apollo regolith breccias, drill cores and soils was compiled into a database where trapped and cosmogenic noble gas component were calculated. These data were used to summarise the history of the lunar regolith contained in the Apollo sample archive. A dichotomy between the "ancient" (determined by the antiquity indicator using the 40Ar/36Artr ratio) regolith samples and those formed in more recent times has been described previously (e.g., McKay et al., 1986).The ancient breccias and soils (&gt;~3.5 Ga) have typically experienced limited amounts of surface exposure (i.e., they are 'immature'). Whereas, regolith samples formed in more recent times ( < 3.5 Ga, << 2 Ga) show a range of maturities. It is likely that the difference in maturity between the ancient and younger breccias reflects the changing collisional conditions of the time i.e., impact flux and regolith turnover rates. Here, 12 lunar meteorite regolith breccias were analysed for their noble gas content (Ne, Ar, Xe isotopes) to determine if lunar meteorites show the same difference between (40Ar/36Ar)tr ratio and maturity. Lunar meteorites in this study and previously published data do show the same negative correlation between (40Ar/36Ar)tr ratio and maturity. Furthermore, many of the lunar meteorite samples have (40Ar/36Ar)tr ratio between 1 and 2.5 indicating antiquity ages of approximately 1-2 Ga. This potentially reflects a declining period of random intermediate impacts bracketing the period between the 'ancient' and 'recent' samples. The same techniques were applied to newly discovered lunar meteorite MIL 13317. This included a full petrology description, mineral chemistry, U-Pb and Pb-Pb ages, and analysis of noble gas content to decipher the regolith history of this new sample. The meteorite is a mixture of mare and highland components (including mare basalts, FAN, Mg-suite and KREEP) with ancient ages (~ 4.3Ga) and a complex regolith history (exposure age ~500 to 800 Ma, antiquity age ~1.92 Ga). MIL 13317 is an important addition to the lunar collection as it contains material from previously unsampled areas of the Moon which is interpreted here to be associated with the northern regions of the Procellarum KREEP Terrane. Work was also begun on Apollo 16 regolith breccias using the same analytical techniques. However, due to instrument issues and friable samples much of the work was not completed and will be continued after the PhD. Understanding the data collected here and the techniques used will feed forward to future missions to the Moon to understand noble gas concentrations in the lunar regolith.

A suite of lightning strike glasses and unmelted starting materials has been studied by electron microscope and Mossbauer spectroscopy to determine Fe oxidation states. Nine of eleven samples are reduced compared to the starting materials; four of the glasses contain Fe0. Only one sample contained evidence of reduction by carbon, and the results support the reduction of Fe as intrinsic to the rapid, high temperature processing during lightning strikes.A thermodynamic modeling code is used to model the formation of moldavite tektites and the reduction of Fe from sediments around the Ries crater. During isentropic cooling from a strong shock, Fe3+ is reduced to Fe2+ at all modeled conditions. The best matches to an average moldavite composition and the compositions of the Bohemian and Bohemian:Radomilice sub-strewn fields occur with a mixture of surface and subsurface sands along a 4500 J/kg-K isentropic cooling path, consistent with an asteroid impact. The Lusatian and Moravian sub-strewn fields are better represented by starting materials of entirely surface sands, consistent with the uppermost layers of surface material having traveled the farthest from the impact.The thermodynamic code is also used to investigate the formation of lunar regolith agglutinates and reduction of Fe to Fe0. Forming Fe0 requires assuming Fe0 is miscible in silicate liquid at elevated temperatures and pressures. When Fe0 is included in the liquid solution, it is stable at modeled conditions. Simple separation of liquid from vapor is not sufficient to reproduce agglutinate glass. When the vapor phase is allowed to partially redeposit and some Fe0 is directly condensed from vapor, the resulting liquid better reproduces mare agglutinate glasses. This model cannot reproduce highland agglutinate glass, because the Al concentration remains too high in the liquid. The best match to mare glass is produced using the <10 µm fraction of the mare soil along the 8000 J/kg-K cooling isentrope at 100 bars, 4370 K with 95% vapor redeposition and 50% of the Fe(g) directly condensed as Fe0. The reduced fulgurite samples and the results of the impact models suggest that Fe reduction is intrinsic to the rapid, high temperature processing of silicates.

No description available.

This study investigated an oxidation-reduction reaction involving a mixture of minerals, glass, and aluminum that exhibited thermite-type reaction behavior. Thermite reactions are a class of Self-propagating High-temperature Synthesis (SHS) reactions. Chemical reactions between raw minerals and a reducing agent, which exhibit thermite-type reaction behavior, are termed geothermite reactions by the author. Geothermite reactions have the potential for use in In-Situ Resource Utilization (ISRU) applications on the Earth, the Moon, Mars, and beyond. A geothermite reaction was shown to occur between two particle size distributions of lunar regolith simulant. Regolith simulant is a naturally occurring mixture of minerals and glass mined from a volcanic ash deposit. The chemical composition of the simulant is similar to actual lunar regolith found on the Moon. The product of the reaction was a ceramic-composite material. The effect of reactant stoichiometry, regolith simulant particle size, and reaction environment on phase formation, microstructure, and compressive strength of the reaction product was investigated. Reaction environments used in this study included a standard atmosphere and a vacuum environment of 0.600 Torr. In addition, the energy required to initiate each reaction using various reaction parameters was measured. X-ray diffraction (XRD) analysis of reaction products synthesized in a standard atmosphere and in vacuum typically indicated the presence of the chemical species: silicon, corundum (α -Al₂O₃), spinel (MgAl₂O₄), and grossite (CaAl₄O₇). Many additional chemical species were present; their occurrence depended on reaction parameters used during synthesis. Diffraction peaks were observed for phases of aluminum nitride within all reaction products formed in a standard atmosphere. Scanning Electron Microscopy (SEM) showed the presence of whisker networks throughout the microstructure for all reactions conducted in a standard atmosphere. Energy Dispersive Spectroscopy (EDS) indicated the presence of aluminum and nitrogen within many of the whiskers. It was hypothesized that many of the whisker networks were composed of phases of aluminum nitride. No whisker networks were observed in the vacuum synthesized reaction products. Maximum mean compressive strengths were found to be ~ 18 MPa and occurred in the coarse particle size distribution of simulant using the smallest quantity of aluminum. Reactant mixtures using a coarse particle size distribution of regolith simulant were found to require substantially more energy to initiate the reaction than the simulant with the fine particle size distribution. / Master of Science

No description available.

In this work, the use of a lunar regolith simulant as feedstock for the direct ink writing additive manufacturing process is explored, the purpose of which is to enable future lunar in-situ resource utilisation. The feasibility of this approach is demonstrated in a laboratory setting by manufacturing objects with different geometries using methyl cellulose or sodium alginate as binding agents and water as liquid phase together with the lunar regolith simulant EAC-1A to create a viscous, printable ‘ink’ that is used in combination with a custom three-axis gantry system to produce green bodies for subsequent sintering. The sintered objects are characterised using compressive strength measurements and scanning electron microscopy (SEM). It is proposed that the bioorganic compounds used in this work as additives could be produced at the site for a future lunar base through photosynthesis, utilising carbon dioxide exhaled by astronauts together with the available sunlight, meaning that all the components used for the dispersion – additive, water (in the form of ice) and regolith – are available in-situ. The compressive strength for sintered samples produced with this method was measured to be 2.4 MPa with a standard deviation of 0.2 MPa (n = 4). It is believed, based on the high sample porosity observed during SEM analysis, that the comparatively low mechanical strength of the manufactured samples is due to a non-optimal sintering procedure carried out at a too-low temperature, and that the mechanical strength could be increased by optimising the sintering process further.