Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 17 of 17 for “"Geostationary orbit"”.
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Probabilistic risk assessment of system-level radiation effects
… in the International Space Station (ISS) and Geostationary Orbit (GEO) environments. The resulting analysis validates certain design choices and identifies the parts and subsystems which contribute most to system risk.
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Radio frequency interference and risk of damage for satellite servicing missions
… transmitted from a servicing satellite in geostationary orbit to couple into the receivers on its intended client, thereby causing interference or even damage to receiver components. It begins by examining the satellite servicing paradigm, and introducing as case studies two missions that …
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Lyapunov feedback control in equinoctial elements applied to low thrust control of elliptical orbit constellations
… are easily fulfilled by using a satellite in a geostationary orbit. However, coverage of higher latitude locales is not as effective with geostationary satellites because the viewing angle from the ground to the satellite will be closer to the horizon, which increases the likelihood of loss of …
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Beam scanning offset Cassegrain reflector antennas by subreflector movement
… for use in radiometric remote sensing from geostationary orbit. This work describes research conducted at Virginia Tech into techniques for beam scanning offset Cassegrain reflector antennas by subreflector translation and rotation. Background material relevant to beam scanning antenna …
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A high gain tri-reflector antenna configuration for beam scanning
High resolution earth observation from geostationary orbit offers several advantages compared to traditional low earth orbit systems. Among the advantages are decreased time to scan the visible geo-disk and the ability to stare at a particular event. The following work is concerned with the design …
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Ultra-thin III-V photovoltaic technology for space applications
… x 10^16 cm^-2, equivalent to > 15 years in the geostationary orbit. In the proposed glass-as-superstrate embodiment, the ultra-thin multi-junction III-V solar cells could eliminate the adhesives and growth substrate supports for significant cost reduction, and maintain high radiation resilience …
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On-Orbit Servicing System Architectures for Proliferated Low Earth Orbit Constellations
On-orbit servicing (OOS) presents new opportunities for refueling, inspection, repair, maintenance, and upgrade of spacecraft (s/c). OOS is a significant area of need for future space growth, enabled by the maturation of technology and the economic prospects. This congestion is leading s/c …
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Optimizing resource allocation in large communications satellite constellations
… users, using thousands of satellites. While the orbital configuration of each design is different, the next generation of satellite communications relies on highly flexible digital payloads, such as phased array antennas, on-board processing, and adaptive modulation and coding schemes. Several …
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Computer vision-based localization and mapping of an unknown, uncooperative and spinning target for spacecraft proximity operations
… are over 100 potential target objects near the Geostationary Orbit belt that are spinning at rates of over 20 rotations per minute. For a number of reasons, it may be desirable to operate in close proximity to these objects for the purposes of inspection, docking and repair. Many of them have an …
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Automated Detection and Analysis of Low Latitude Nightside Equatorial Plasma Bubbles
… are analyzed. GOLD provides consistent data from geostationary orbit with the eastern region of the Americas, Atlantic, and western Africa. The optical data can be used to pick out gradients in brightness along the 135.6 nm wavelength which correlate with the location of EPBs in the nightside …
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Observations of Non-Migrating Tides in the Middle Thermosphere
… thermospheric parameters, the former from geostationary orbit (GEO) and the latter from low Earth orbit. Both missions infer the daytime column O/N2 ratio, while GOLD also retrieves the daytime thermospheric disk temperature. Traditional spectral tidal decomposition cannot be employed on …
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Modeling and simulation of permanent on-orbit servicing infrastructures dedicated to modularized earth-orbiting platforms
… and cost-effectiveness of permanent on-orbit servicing (OOS) infrastructures providing services to multiple serviceable platforms in coplanar medium Earth orbit (MEO) and/or geostationary orbit (GEO). The customer satellites are assumed to be made of elementary units (EUs). EUs are small …
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Optimal control techniques for multimode propulsion mission design in cislunar space
… are developed for solving optimal multimode orbital transfers. Using an indirect approach results in the automatic selection of the burn sequence (i.e., which mode should be used at every instant). This yields more optimal transfers in comparison to the traditional approach in which the burn …
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Modelling the Exposure of Satellites in Medium Earth Orbit to Proton Belt Radiation
… Earth's proton radiation belt pose a hazard to orbiting spacecraft. In particular, solar cells are prone to degradation caused by non-ionising collisions with protons in the energy range of several megaelectron volts, which can ultimately shorten the lifespan of a mission. Dynamic enhancements …
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Antenna systems research
… on large satellites, and future technology, geostationary orbit multi-role satellites with 'plug-in' payloads. New satcom terminal antenna configurations has been a very important area of research, resulting in high performance circularly polarized antenna configurations for small terminals …
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Impact evaluation of in-space additive manufacturing and recycling technologies for on-orbit servicing
Made available in DSpace on 2018-09-04T20:42:00Z (GMT). No. of bitstreams: 2 SEARS-THESIS-2018.pdf: 502754 bytes, checksum: 9fc27d97554ffc268d11cbb6ddbe49d3 (MD5) LICENSE.txt: 4210 bytes, checksum: 0cc39aa6e04642f01c5b652b842fc32a (MD5) Previous issue date: 2018-04-27
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Satellite multiple access protocols for land mobile terminals. A study of the multiple access environment for land mobile satellite terminals, including the design analysis and simulation of a suitable protocol and the evaluation of its performance in a U.K. system.
… to a large number of small terminals. Three orbit options are studied, namely the geostationary, elliptical (Molniya) and inclined circular orbits. These are investigated for various mobile applications and the choice of the Molniya orbit is justified for a U. K. system. Frequency, Time and …