Thesis (M. S.)--Oklahoma State University, 2006. / Vita. Includes bibliographical references.

<p>The incorporation of extremely compact multifunctional microsystems is a highly profitable long-term approach in spacecraft design. These systems bring substantial launch-cost reductions, and enable exciting space exploration and science missions.</p><p>Silicon microsystems technology is an adequate choice for the multifunctional microsystem development. However, the development of basic microsystems technology cannot be financed within application-specific space missions. Rather, the microsystems technology should be matured through fundamental research.</p><p>Silicon microsystems technology was used to develop a cold gas microthruster system suitable for minute movements of spacecraft (low Δv). In a hybrid integration, the system unit contains three silicon microsystem parts with four individual thrusters in total, together with external control electronics. The total mass is 0.35 kg.</p><p>Further integration will result in a mass of 0.08 kg. Complete system integration means that all package and interconnection levels are integrated into the silicon microsystem units. Several vital issues must be addressed, e.g. the reliable bonding of silicon wafers, the microfabrication process compatibility, and the manufacture process sequence. A graphical tool is introduced for process sequence evaluation.</p><p>Wafer bonding is used as fabrication process, assembly tool, and packaging technique. The quality and reliability of the bonded interfaces must be assessed in order to secure the operation of the microsystems in space. Therefore, statistical methods for burst test evaluation have been developed.</p><p>Weibull fracture probability functions have been derived in order to interpret the bond quality. In addition, rank-sum tests on spot series and analysis of variance are performed for bond quality diagnostics. The dependence on annealing temperature and surface-activation are presented, together with diagnosed degradation of insufficiently annealed bonds due to different spaceflight environments (thermal cycling, vibration, γ-irradiation).</p>

The incorporation of extremely compact multifunctional microsystems is a highly profitable long-term approach in spacecraft design. These systems bring substantial launch-cost reductions, and enable exciting space exploration and science missions. Silicon microsystems technology is an adequate choice for the multifunctional microsystem development. However, the development of basic microsystems technology cannot be financed within application-specific space missions. Rather, the microsystems technology should be matured through fundamental research. Silicon microsystems technology was used to develop a cold gas microthruster system suitable for minute movements of spacecraft (low Δv). In a hybrid integration, the system unit contains three silicon microsystem parts with four individual thrusters in total, together with external control electronics. The total mass is 0.35 kg. Further integration will result in a mass of 0.08 kg. Complete system integration means that all package and interconnection levels are integrated into the silicon microsystem units. Several vital issues must be addressed, e.g. the reliable bonding of silicon wafers, the microfabrication process compatibility, and the manufacture process sequence. A graphical tool is introduced for process sequence evaluation. Wafer bonding is used as fabrication process, assembly tool, and packaging technique. The quality and reliability of the bonded interfaces must be assessed in order to secure the operation of the microsystems in space. Therefore, statistical methods for burst test evaluation have been developed. Weibull fracture probability functions have been derived in order to interpret the bond quality. In addition, rank-sum tests on spot series and analysis of variance are performed for bond quality diagnostics. The dependence on annealing temperature and surface-activation are presented, together with diagnosed degradation of insufficiently annealed bonds due to different spaceflight environments (thermal cycling, vibration, γ-irradiation).

<p>Energetic neutral atoms (ENAs) are produced whenever a stellar wind encounters a neutral atmosphere. If a stellar wind proton comes sufficiently close to a neutral a charge-exchange reaction may take place, transforming the proton into an ENA. Unaffected by magnetic and electric fields, ENAs provide an opportunity for global imaging of stellar wind interactions.</p><p>This thesis presents methods and results of numerical modelling of stellar wind interactions. In particular it treats in depth production of ENAs at comets, Mars and the extrasolar planet HD 209458b.</p><p>Sufficiently accurate numerical models of stellar wind interactions require extensive computations. Parallel computing has therefore been used throughout the work, both for fluid and particle simulations of space plasmas. This thesis describes the use of a general simulation tool, providing parallel computing for space plasma simulations.</p><p>The thesis presents estimations of the magnitude and morphology of the ENA production at comets and HD 209458b. It compares the results obtained with observations and analyzes them in the light of ENA production at similar objects. Also, simulated ENA images for Mars were produced and compared to observations.</p>

Energetic neutral atoms (ENAs) are produced whenever a stellar wind encounters a neutral atmosphere. If a stellar wind proton comes sufficiently close to a neutral a charge-exchange reaction may take place, transforming the proton into an ENA. Unaffected by magnetic and electric fields, ENAs provide an opportunity for global imaging of stellar wind interactions. This thesis presents methods and results of numerical modelling of stellar wind interactions. In particular it treats in depth production of ENAs at comets, Mars and the extrasolar planet HD 209458b. Sufficiently accurate numerical models of stellar wind interactions require extensive computations. Parallel computing has therefore been used throughout the work, both for fluid and particle simulations of space plasmas. This thesis describes the use of a general simulation tool, providing parallel computing for space plasma simulations. The thesis presents estimations of the magnitude and morphology of the ENA production at comets and HD 209458b. It compares the results obtained with observations and analyzes them in the light of ENA production at similar objects. Also, simulated ENA images for Mars were produced and compared to observations.

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2017. / The aim of this thesis is to investigate the applications of multifunctional compos- ite (MFC) technology to nano-satellite structures and to produce a working concept design, which can be implemented on future Cube-Satellites (CubeSats). MFC tech- nologies can be used to optimise the performance of the satellite structure in terms of mass, volume and the protection it provides. The optimisation of the structure will allow further room for other sub-systems to be expanded and greater payload allowance. An extensive literature view of existing applications of MFC materials has been conducted, along with the analysis of a MFC CubeSat structural design account- ing for the environmental conditions in space and well-known design practices used in the space industry. Numerical analysis data has been supported by empirical analysis that was done where possible on the concept material and structure. The ndings indicate that the MFC technology shows an improvement over the conventional alu- minium structures that are currently being used. Improvements in rigidity, mass and internal volume were observed. Additional functions that the MFC structure o ers include electrical circuitry and connections through the material itself, as well as an increase electromagnetic shielding capability through the use of carbon- bre composite materials. Empirical data collected on the MFC samples also show good support for the numerical analysis results. The main conclusion to be drawn from this work is that multifunctional composite materials can indeed be used for nano-satellite structures and in the same light, can be tailor-made to the speci c mission requirements of the satellite. The technology is in its infancy still and has vast room for improvement and technological development beyond this work and well into the future. Further improvements and additional functions can be added through the inclusion of various other materials.

”The Eagle has landed”. With this words, astronaut Neil Armstrong, together with astronaut Edwin ”Buzz” Aldrin, confirmed the safe landing on the Moon of the Apollo11 on July 20th, 1969. This achievement would have never been possible without the engineering behind the construction of the Moon lander. One of the most innovative features installed aboard was the pintle injector, a specific type of injector capable of precise metering of the propellants into the combustion chamber, and capable of throttling. Furthermore, the pintle injector has demonstrated its inherent combustion stability andgood mixing properties over time. The current work serves as a feasibility study for the use of an electric motor as the actuator for the pintle. This paper is the result of a 9-month internship at ArianeGroup GmbH, which is investigating the use of a pintle injector as a back-up option for a future ESA lunar lander mission. A preliminary design of the pintle was already produced, and the scope of this work is the design of the mechanical linkages and the actuation of the injector, with the choice of the method of actuation, the electric motor and the necessary components.

The PAMELA satellite experiment will soon be launched and during its 3 year mission perform measurement of charged particle fluxes in the cosmic radiation. PAMELA is specifically designed to identify antiprotons and positrons in the vast background of other charged particles. These antiparticle measurements will be performed using: a permanent magnet spectrometer, a scintillator based time of flight system, an electromagnetic imaging calorimeter, a transition radiation detector and a scintillator triggered neutron detector. There is also a scintillator based anticoincidence system to reject spurious triggers from out of acceptance events (developed and built at KTH). These detectors will allow the background in the antiproton and positron measurements to be significantly reduced, and PAMELA will thus be able to perform high precision measurements with unprecedented statistics and over a wide energy range, far surpassing any previous experiment. To determine the antiparticle identification and background rejection capability of the experiment, studies have been performed using simulations and data collected at particle beams. These studies have focused on: the proton rejection in positron measurements (using the calorimeter), contamination by locally produced pions in antiproton measurements and estimations of the expected statistics due to the energy dependence (caused by e.g. the geomagnetic field and the magnetic field in the spectrometer) of the gathering power. This work significantly extends previous studies of the PAMELA performance in antiparticle identification.

Nowadays, GIS techniques have been widely used in every walk of life. Owing to the rapid urban growth, it is of importance to plan and develop the cities in a reasonable and scientific way. As a result, optimum sites of different constructions should be considered to make full use of land resources and optimize urban structure. Although the traditional field-survey method is important, GIS-based multi-criteria analysis (MCA) provides a more reasonable and scientific way in site selection issue. Weihai, our study area, is one of the fastest developing coastal cities in China. Owing to the rapid urban expansion, Weihai government municipality planned to develop the Poyu town into a new district with multifunctions. In consideration of its advantages in natural resources and geographic position, a holiday resort is proposed. In the aim of applying GIS-based MCA in site selection, this thesis would present an experiment to select the optimal site for a holiday resort with the help of GIS techniques. The data used in this project is a satellite image and digital elevation data of Poyu town. The satellite image has been digitized to obtain the current land use map, based on which constraint maps and factor maps have been made to make preparation of multi-criteria analysis. Finally, the multi-criteria analysis model has been made. The weights for multi-criteria analysis are obtained from the advice of experienced people in Weihai Planning Bureau and also earlier studies on the site selection. There are three sets of weights based on three themes that have been used in this project. The three themes which were fruit-picking theme, seascape and seafood theme as well as leisure and recreation theme were decided based on the results of the questionnaire. Through the discussions of the results, a final selected site for the holiday resort was determined. It includes the optimal site for the main part focusing on both fruit picking theme and leisure and recreation theme and also the optimal site for an accessory part focusing on seascape and seafood theme. The final section concludes the general project work, its perspectives and the function of GIS-based MCA in site selection.

<p>The PAMELA satellite experiment will soon be launched and during its 3 year mission perform measurement of charged particle fluxes in the cosmic radiation. PAMELA is specifically designed to identify antiprotons and positrons in the vast background of other charged particles. These antiparticle measurements will be performed using: a permanent magnet spectrometer, a scintillator based time of flight system, an electromagnetic imaging calorimeter, a transition radiation detector and a scintillator triggered neutron detector. There is also a scintillator based anticoincidence system to reject spurious triggers from out of acceptance events (developed and built at KTH). These detectors will allow the background in the antiproton and positron measurements to be significantly reduced, and PAMELA will thus be able to perform high precision measurements with unprecedented statistics and over a wide energy range, far surpassing any previous experiment. To determine the antiparticle identification and background rejection capability of the experiment, studies have been performed using simulations and data collected at particle beams. These studies have focused on: the proton rejection in positron measurements (using the calorimeter), contamination by locally produced pions in antiproton measurements and estimations of the expected statistics due to the energy dependence (caused by e.g. the geomagnetic field and the magnetic field in the spectrometer) of the gathering power. This work significantly extends previous studies of the PAMELA performance in antiparticle identification.</p>