Resumo: Uma abordagem analítica para o movimento rotacional de satélites artificiais estabilizados por rotação é apresentada, considerando os satélites em órbita elíptica e a influência do torque magnético residual. O torque magnético residual resulta da interação entre o campo magnético residual do satélite e o campo geomagnético, sendo este representado pelo modelo de quadripolo. As equações do movimento são descritas em termos do módulo da velocidade de rotação do satélite, da declinação e da ascensão reta do eixo de rotação do satélite. As componentes médias do torque residual em um sistema fixo no satélite são determinadas para um período orbital. Uma solução analítica para as equações do movimento é determinada, sendo válida para um período orbital. Por esta solução observa-se que o torque residual não afeta o módulo da velocidade de rotação, contribuindo apenas para as variações temporais da ascensão reta e declinação do eixo de rotação, associadas com a precessão e deriva do eixo de rotação do satélite. Aplicações são realizadas para os Satélites de Coleta de Dados Brasileiros SCD1 e SCD2, mostrando uma concordância entre os resultados obtidos pela teoria e os dados fornecidos pelo Centro de Controle de Satélites do INPE. O comportamento do erro gerado na direção do eixo de rotação do satélite é também apresentado, sendo que os desvios obtidos se mostram de acordo com as precisões requeridas para as missões destes satélites. / Abstract: An analytical approach is show for attitude motion of the spin stabilized artificial satellite in an elliptic orbit. Residual magnetic torque is considered and the geomagnetic torque is defined by the quadripole model. The equations of motion are described by the magnitude of the spin velocity, right ascension and declination of the spin axis. The components of the averaged residual torque are computed for one orbital period in a satellite reference system. An analytical solution is presented and it is valid for one orbit period. By this solution it is possible to observe that the residual torque causes the precession and the drift of the spin axis, but it does not affect the magnitude of spin velocity. Some applications are done for Brazilian Satellite SCD1 and SCD2, and they show the agreement of the theory results and the data provide by INPE Satellite Control Center. The behavior of the error in the spin axis direction is also presented and this error agrees with the required precision of these satellite missions. / Orientador: Maria Cecília F. de Paula Santos Zanardi / Coorientador: Hélio Koiti Kuga / Banca: Rodolpho Vilhena de Moraes / Banca: Valcir Orlando / Mestre

Este trabalho apresenta o desenvolvimento de um equipamento para testes eletrônicos, GSE (Ground Support Equipment), em nível de sistema e subsistema do imageador multiespectral (MUX) do satélite CBERS3&4, a primeira câmera espacial desenvolvida no país. O projeto foi realizado com base em um modelo de referência para o desenvolvimento de produtos mecatrônicos. O GSE utiliza instrumentação virtual, um banco óptico e outros equipamentos controlados por computador e integrados por uma eletrônica própria para testar todos os requisitos funcionais do subsistema. Além disso, é capaz de simular outros subsistemas do satélite que possuam interface com a câmera MUX, tais como o DDR (Digital Data Recorder), OBDH (On-Board Data Handler) e o EPSS (Eletrical Power Supply Subsystem). Como resultado, este trabalho apresenta os testes realizados pelo equipamento desenvolvido, ressaltando sua funcionalidade. / This work presents the development of an equipment for electronic tests, GSE (Ground Support Equipment), in system and subsytem levels of the multispectral imager from CBERS3&4 satellite, the first camera for space applications developed in the country. This project was developed using a reference model for mechatronic products development. GSE utilizes virtual instrumentation, an optical bench and other equipments controled by computer and integrated by its own electronics to test all subsystem functional requirements. Besides, GSE is capable to simulate all others satellite subsystems which share interfaces with MUX, such as DDR (Digital Data Recorder), OBDH (On-Board Data Handler) and EPSS (Eletrical Power Supply Subsystem). As a result, this work presents the tests accomplished by the developed equipment, emphasizing its functionality.

Research has been completed to determine the most effective thermal control architecture for modular satellites. This research investigated principles of modularity, modular spacecraft examples, thermal control methods, and advanced thermal control technologies. A modular spacecraft was designed as a case study to determine key influences and issues. A number of thermal control architectures were developed. Each was evaluated for compatibility with modularity principles, thermal control performance, and a realizable implementation. Thermal control performance was determined by simulating on-orbit conditions for a number of design reference missions, including traditional thermal control architecture used for comparison. An effective thermal control architecture was found that has all desired attributes. The methods of development, simulation, and evaluation are presented with results and key findings.

A fundamental investigation of the use of ultrasonic consolidation (UC) to produce deck panels for small satellites was undertaken. Several fabrication methods for producing structural panels and decking were analyzed. Because of its ability to create aluminum objects in an additive fashion, and at near-room temperatures, UC was found to be a powerful solution for creating highly integrated and modular satellite panels. It also allowed a lightweight and stiff deck to be fabricated without the use of adhesives. A series of experiments were performed to understand the issues associated with creating a sandwich-type structure using UC. The experiments used a peel test apparatus to evaluate the bond strength for various geometric configurations and materials. Aluminum 3003 was chosen as the sole material constituting the deck panel. The honeycomb lattice was found to offer the best core configuration due to its ability to resist vibration from the sonotrode and provide adequate support for pressure induced by the sonotrode. Support materials for enhancing the bonding of the facings to the core were investigated but did not lead to implementation. A CAD model was created to integrate the honeycomb core, facings, and modular bolt pattern into the ultrasonically consolidated structure. The model was used to develop a build procedure for fabricating the deck on the UC machine. A finite element analysis was performed that used an equivalent properties method to represent the deck. The stiffness of a prototype deck was evaluated in a three-point bending test and the results were found to correlate with the finite element model. A sine sweep vibration test was then performed on the prototype deck panel to measure its natural frequencies. Finally, a case study was performed on a deck built for the TOROID spacecraft. A final deck panel was designed using the results from the prototype. The deck included the USUSat bolt pattern, vented honeycomb, and a reinforced rim. The cost and benefits of the final deck panel versus traditional fabrication methods were outlined.

Tracking an individual species has always been a challenge for scientists, especially when one has to make sure to not change its natural movement pattern. When the number of individuals being tracked is increased and water is added to the equation, the task becomes next to impossible. But thanks to technologies and tracking methods like telemetry, the task of tracking any species without affecting the natural movement pattern has not only become a reality but easily accessible to scientists. Underwater acoustic telemetry has become a standard tool for fisheries biologist to study the movement pattern of the fish (Heupel). This project develops a minimalistic database designed to meet the needs of the telemetry systems. The database is optimized for storing a large number of datasets generated by the telemetry system and also for the most common queries run against the system.

CubeSat development has seen a rise since the first launch in 2003 due to faster design process and low launch costs. It has played a vital role in providing access to space to small start-ups and academic organizations with low budgets. It has also enabled the testing of different upcoming technologies in space and has helped in providing hands-on experience to students taking part in design of such platforms. University of Pisa, in collaboration with SITAEL, has also taken an initiative to design and develop a CubeSat to test the FEEP thruster, design of which is presented in the thesis. A FEEP system was designed to fit within 1U dimensions and with a dry mass of approximately 820 grams. The system is based on slit emitter which provides an advantage over already available technologies in the market which uses needle emitters. Slit emitter scan achieve multiple Taylor cones without the need of clustering as used in needle emitters and also have a higher Thrust to Power Ratio. A propellant comparison was done considering all the properties required for an ideal propellant for a FEEP system. This comparison led to the selection of indium as working propellant which has an atomic mass of 114.8 u and a melting point of 156.6 °C. The FEEP system was designed keeping in mind easy assembling and modularity of thruster for ease in changing parts. The design consists of three different modules that are assembled separately and then joined together to complete the assembling of the system. The propellant tank, which also houses the emitter, has an internal volume of 32.75 cm3 and can hold approximately 240 grams of indium, which has a density of 7.31 g/cm3. During mission analysis, a 600km altitude orbit was proposed by analyzing the amount of propellant required for drag compensation and de-orbit maneuver at different altitudes with worst case values for ballistic coefficient and Thrust to Weight Ratio. At this altitude, the propellant requirement is 254.4 grams, 14.4 grams more than that of what can fit in the propellant tank of the designed thruster. However, both design of the system and mission analysis are ongoing processes and changes would be made in the future to either one or both to meet the requirements.

No description available.

We studied the global climatology of mid- and low-latitude F region daytime neutral winds using extensive measurements by the Wind Imaging Interferometer (WINDII) instrument on board the Upper Atmosphere Research Satellite (UARS). Quiet-time winds are mostly poleward and westward during the day, and are generally 5-20 m/s smaller in the longitudinal sector closest to the magnetic pole, compared to longitudinally averaged winds. The pre-noon zonal winds are less westward with increasing solar flux, while the post-noon meridional winds are less poleward . Our quiet-time results are in good agreement with the NCAR ThermosphereIonosphere- Electrodynamics General Circulation Model (TIEGCM). We computed residual winds by subtracting quiet-time values calculated along the satellite orbit, which effectively removes average measurement bias. Using these residuals, we studied the average change in the winds under disturbed conditions. The zonal disturbance winds are mostly westward, increase with latitude, and have largest values in the late afternoon sector. In general, the meridional perturbation winds are equatorward, increase linearly with latitude, and decrease from morning to afternoon hours. The zonal and meridional perturbations increase roughly linearly with Kp. We developed empirical analytical models for the disturbance winds from 60° to the equator; these model winds are in poor agreement with results from the empirical Horizontal Wind Model. There are also important discrepancies between the average perturbations winds from WINDII and TIEGCM. We studied the average time-dependent development of disturbance winds during geomagnetic storms. The onset of a storm is characterized by equatorward surges, mostly in the morning sector, that reach the equator in about 2 h. These surges lessen 5-6 h after the onset of a storm, but subsequently increase, reaching their largest values about 15 h after the start of the storm before leveling off or diminishing. Following the end of typical storms, the disturbance winds decrease quickly but oscillate for at least one 8-9 h cycle. We developed time-dependent analytical models of the disturbance winds as a function of the polar cap index at key storm time lags. Our results are consistent with predictions from theoretical models. (146 pages)

Land-cover identification and mapping are an integral part of natural resource planning and management. Satellite imagery provides a way to obtain land cover information, particularly for large tracts of land such as those administered by federal and state agencies. This study assesses the usefulness of the Brightness/Greenness Transformation of Landsat Thematic Mapper data for differentiating conifer forest types in northern Utah. Satellite data for the Logan Ranger District of the Wasatch-Cache National Forest were classified into 27 vegetation classes. Of these, nine were determined to be conifer classes and were used in subsequent analyses. Ten sites of each conifer class type were field checked and vegetation and physical site characteristics recorded. The Brightness/Greenness Transformation was able to distinguish conifer areas from other vegetation types. High-density conifer classes were classified at 94 percent accuracy. Low-density conifer classes were classified correctly 65 percent of the time. The Brightness/Greenness Transformation alone met with limited success in distinguish ing between conifer species. Each class showed great variability with respect to major overstory species. Analysis of variance indicated that none of the site factors measured consistently corresponded with the spectrally designated classes. While several factors differed significantly among classes, no factor was significantly different for all c l ass-pair combinations. Correlation analysis revealed that brightness, greenness, and wetness values related more to environmental values than to conifer species. Brightness was highly correlated with percent of exposed soil on the site. Greenness was highly correlated to the presence of deciduous and herbaceous vegetation. Wetness was highly correlated to total tree and conifer cover values. Adding slope and aspect data to the Brightness/Greenness Transformation classes with the highest percentages of canopy cover did allow separation of lodgepole pine and Douglas fir. High percentagecanopy cover sites on slopes less than 35 percent were classified as lodgepole pine with 89 percent accuracy. On slopes greater than or equal to 35 percent, Douglas fir was found with 79 percent accuracy.

Cube Satellite (CubeSat) launches have been on the rise since its first launch in2003. This popularity is mainly due to faster design process and lower launch costs.However, most CubeSats are launched into Low Earth Orbits (LEOs), with nomissions to Geostationary Transfer Orbits (GTOs). However, many mission areplanned for the next half-decade.A major challenge to launch a CubeSat into a GTO is the thermal environmentof the higher altitude orbits. These orbits are significantly colder due to reducedheating from Earth’s planetary and albedo radiations, and a possibility for longereclipses due to the eccentricities of GTOs.A thermal investigation of the thermal environment was done using the Foresailmissions as examples, as the missions currently are set to fly the first missions toPolar LEO. The trajectories for the second Foresail mission are being evaluated,with the GTO being a strong contender. This thermal investigation is done througha comparative study of the two missions. The thermal effects of a few missionspecific scenarios were also evaluated.This provided a holistic thermal design of the first Foresail mission. A region specificthermal solution for the battery was analyzed. The various mission scenarios andtheir comparisons with the LEO mission, also formed a basis of the feasibility ofvarious situations on the second mission. Moreover, the results, in part assessedthe thermally feasibility to launch a 3U CubeSat into a GTO.The results showed GTOs show larger magnitude of variation of thermal loads ascompared to LEOs. However, these variations are more gradual due to the largerorbital periods. A 3U CubeSat can be launched into both, the LEO and GTOenvironments with passive thermal control. The properties of the thermal coatsvary slightly. However, it is not possible to passively control the CubeSat if theeclipse occurred at the aphelion of the orbit.