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Thesis (MScEng)--University of Kwa-Zulu Natal, 2011. / ENGLISH ABSTRACT: This research investigates the collection of concentrating solar energy and its transmission through optical fibres for use in high temperature applications such as lunar in-situ resource utilisation (ISRU) programmes, solar power generation and solar surgery. A prototype collector, known as the Fibre Optic Concentrating Utilisation System (FOCUS), has been developed and is capable of delivering high energy fluxes to a remote target. Salient performance results include flux concentrations approaching 1000 suns with an overall optical efficiency of 13%, measured from the inlet of the collector to the fibre outlet. The system comprises a novel solar concentrator designed to inject solar energy into a four metre long fibre optic cable for the transmission of light to the target. A nonimaging reflective lens in the form of a 600 mm diameter ring array concentrator was chosen for the collection of solar energy. Advantageous characteristics over the more common parabolic dish are its rearward focusing capacity and single stage reflection. The ring array comprises a nested set of paraboloidal elements constructed using composite material techniques to demonstrate a low-cost, effective fabrication process. At concentrator focus, a fibre optic cable of numerical aperture 0.37 is positioned to transport the highly concentrated energy away from the collector. The cable is treated to withstand UV exposure and high solar energy flux, and allows flexibility for target positioning. A computational analysis of the optical system was performed using ray tracing software, from which a predictive model of concentrator performance was developed to compare with experimental results. Performance testing of FOCUS was conducted using energy balance principles in conjunction with a flat plate calorimeter. Temperatures approaching 1500°C and flux levels in the region of 1800 suns were achieved before injection to the cable, demonstrating the optical system‟s suitability for use in high flux applications. During testing, peak temperatures exceeding 900°C were achieved at the remote target with a measured flux of 104 W/cm2 at the cable outlet. The predicted optical efficiency was 22%, indicating that further refinements to the ray trace model are necessary, specifically with regard to losses at the inlet to the cable. FOCUS was able to demonstrate its usefulness as a test bed for lunar in-situ resource utilisation technologies by successfully melting a lunar soil simulant. The system permits further terrestrial-based ISRU research, such as oxygen production from regolith and the fabrication of structural elements from lunar soil. / Sponsored by the Centre for Renewable and Sustainable Energy Studies

Increased interestin In-Situ Resource Utilization (ISRU) concept for lunar outpost construction has motivated to the development of autonomous excavation rovers. The system design of two autonomous excavation rover prototypes UNEMEEP and The Musketeers are detailed in this thesis. The problem of autonomous excavation has been explored in the area of agriculture and mining. However, to date very little have been accomplished in the area of an autonomous excavation rover aimed towards space application. A hybrid position and admittance control strategy is implemented on autonomous excavation rovers to achieve digging and leveling capabilities. Integration tests and a full scale multirover mission scenario were also carried out. The results from the experiments are analyzed and recommendations are made to improve upon the capabilities of the rovers.

Increased interestin In-Situ Resource Utilization (ISRU) concept for lunar outpost construction has motivated to the development of autonomous excavation rovers. The system design of two autonomous excavation rover prototypes UNEMEEP and The Musketeers are detailed in this thesis. The problem of autonomous excavation has been explored in the area of agriculture and mining. However, to date very little have been accomplished in the area of an autonomous excavation rover aimed towards space application. A hybrid position and admittance control strategy is implemented on autonomous excavation rovers to achieve digging and leveling capabilities. Integration tests and a full scale multirover mission scenario were also carried out. The results from the experiments are analyzed and recommendations are made to improve upon the capabilities of the rovers.

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (p. 170-178).

Thesis (Ph.D.)--Drexel University, 2009. / Includes abstract and vita. Includes bibliographical references (leaves 205-220).

Thesis (M.S.)--Ohio State University, 1986. / Includes bibliographical references (leaves 141-146). Available online via OhioLINK's ETD Center

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.

The development of a flexible, high-fidelity, generic simulation of transatmospheric and interplanetary motion is described. The simulation incorporates aerodynamic and gravitational force modelling implemented in a Cartesian reference co-ordinate set. Propagation of the motion of a vehicle is carried out in a "working" reference frame whose origin is determined by the current gravitational sphere of influence. A semi-analytic model of planetary motion propagates the motion of the nine planets and six major moons, allowing simulation at any point within the solar system. Expansion and improvement of the model is facilitated through the vector formulation of the problem. The use and applicability of the method of matched asymptotic expansions is examined as a means of producing high quality trajectory predictions quickly and easily. Ballistic launch and entry trajectories are considered incorporating a velocity dependent model for the aerodynamic drag coefficient. Using the derived relations direct launch is considered as a low-cost means of transporting acceleration insensitive payloads to a space station in low Earth orbit. In addition, it is shown that the high quality trajectory predictions may be obtained using a simple spreadsheet package. Analytic modelling is also used as the basis of a highly robust, computationally efficient, controller design for autonomous aerocapture in the context of the lunar return problem. The validity of this approach to lunar return is examined and found to be of considerable potential in both its robustness and the potential improvements in payload mass-fraction available through the substantial fuel savings over direct return to Earth or propulsive return to a space station. The study shows that, using the derived control, the aerocapture manoeuvre can be successfully performed with existing material and technological capabilities.

abstract: Stratification is a dominant feature of all planetary interiors. Fine-scale structure associated with layering, as well as heterogeneities hold important clues on a planet's compositional, thermal, and dynamical state, as well as its evolution. This research centers on using data from seismic arrays, networks of seismic sensors, and array processing methodologies to map the fine scale structure in the Earth's upper mantle and deep layering in the Moon - Earth and Moon are the only two planetary bodies with seismic available data for such analyses. Small-scale structure in the Earth's upper mantle can give rise to seismic wave scattering. I studied high frequency data from the Warramunga Array in Australia using array seismology. I developed and employed back-projection schemes to map the possible upper mantle scattering or reflection locations. Mapped scatterers show good correlation to strong lateral P-wave velocity gradients in tomography models and may be associated with the complex tectonic history beneath north of Australia. The minimum scale of scatterers relates to the seismic wavelength, which is roughly between 5 and 10 km in the upper mantle for the frequencies we study. The Apollo Passive Seismic Experiment (APSE) consisted of four 3-component seismometers deployed between 1969 and 1972 that continuously recorded lunar ground motion until late 1977. I studied the deep lunar interior with array methods applied to the legacy APSE dataset. The stack results suggest the presence of a solid inner and fluid outer core, overlain by a partially molten boundary layer, but their reflector impedance contrasts and reflector depths are not well constrained. With a rapidly increasing number of available modern broadband data, I developed a package, Discovery Using Ducttape Excessively (DUDE), to quickly generate plots for a comprehensive view of earthquake data. These plots facilitate discovery of unexpected phenomena. This dissertation identifies evidence for small-scale heterogeneities in Earth's upper mantle, and deeper lunar layering structure. Planetary interiors are complex with the heterogeneities on many scales, and discontinuities of variable character. This research demonstrates that seismic array methods are well-suited for interrogating heterogeneous phenomena, especially considering the recent rapid expansion of easily available dense network data. / Dissertation/Thesis / Ph.D. Geological Sciences 2011