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 20 of 108 for “"Low-Earth Orbit (LEO)"”.
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Calibration and validation for CubeSat Microwave Radiometers
… radiometers deployed on nanosatellites in Low Earth Orbit (LEO) are now demonstrating the ability to provide science-quality weather measurements. For instance, the Micro-sized Microwave Atmospheric Satellite-2A (MicroMAS-2A) is a 3U CubeSat launched in January 2018 that provided the first …
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Autonomous navigation of distributed spacecraft using intersatellite laser communications
… such as determining and disseminating orbit solutions. Several autonomous navigation methods have been previously studied, using some combination of on-board sensors that can measure relative range or bearing to known bodies, such as horizon and star sensors (Hicks and Wiesel, 1992) or …
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Deep Learning for Space Object Density Distribution Prediction
The rapid growth of artificial objects in Low Earth Orbit (LEO) has heightened concerns over orbital congestion and collision cascades, known as Kessler Syndrome. Traditional high-fidelity models, while accurate, are computationally intensive and poorly scalable. This thesis introduces a machine …
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GNSS-based relative navigation for LEO nanosatellite laser communications
… has the objective of demonstrating the first Low-Earth orbit (LEO) nanosatellite crosslink. The need for precise and accurate pointing with laser instruments motivates a formalized, systematic approach to fulfilling this need called Pointing, Acquisition, and Tracking (PAT). The focus of this …
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Evaluating the effect of spacesuit glove fit on functional task performance
… per mission increases with exploration beyond low Earth orbit (LEO), it is essential that crewmembers conduct suited activities in a manner that enables acceptable performance and minimizes the risk of injury. Currently, knowledge gaps exist in how to dene optimal suit t, how to more …
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Low Earth Orbit Spacecraft Slotting: Towards an Implementable Proposal
The growth in the number of proposed low Earth orbit (LEO) satellites is driven primarily by large commercial communications constellations. The launch of even half of the proposed satellites would result in an order-of-magnitude increase in active spacecraft traffic, with significant implications …
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Investigation of Orbital Debris Situational Awareness with Constellation Design and Evaluation
Orbital debris is a current and growing threat to reliable space operations and new space vehicle traffic. As space traffic increases, so does the economic impact of orbital debris on the sustainability of systems that increasingly support national security and international commerce. Much of the …
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Ionospheric Simulator (IonSim): Simulating Ionospheric conditions in a vacuum chamber
… analyzers (RPAs) and ion traps are routinely flown in low earth orbit (LEO) to provide data for seeding/improve ionospheric models. This thesis describes and characterizes a new ion source that can be used to test and calibrate these space-borne instruments inside a laboratory vacuum chamber. …
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Deep learning for downscaling GOES-18 measurements for wildfire detection
… for frequent observations but suffers from low spatial resolution. In contrast, low Earth orbit (LEO) satellites like Suomi-NPP, NOAA-20, and NOAA-21 with the Visible Infrared Imaging Radiometer Suite (VIIRS) imager provide high spatial resolution but with limited temporal coverage. To …
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Sensor Package Analysis and Simulation for Direct Sensor-to-Satellite Links
… investigates the design and the performance of low-power microsensors that communicate directly to a satellite or a constellation of satellites. Information is spread using pseudo noise (PN) or Barker codes. The sensors use a single circular microstrip patch element with a wide beamwidth or a …
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On-Orbit Cryogenic Propellant Storage Optimization
<p>The optimization of an on-orbit Cryogenic Propellant Storage (CPS) system enables human exploration missions by reducing launch vehicle mass to orbit requirements and providing an extensible approach for human spaceflight missions to near-Earth asteroids, the moon, and Mars. The optimal CPS …
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Dual High-Voltage Power Supply for Use on Board a CubeSat
… on sending simple data and photographs back to Earth. Since then, vast improvements have been made by over 40 universities and private firms, and now CubeSats are beginning to look towards interplanetary travel. These small satellites could provide a cost effective means of exploring the galaxy, …
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Dual Satellite Coverage using Particle Swarm Optimization
A dual satellite system in a Low Earth Orbit, LEO, would be beneficial to study the electromagnetic occurrences in the magnetosphere and their contributions to the development of the aurora events in the Earth's lower atmosphere. An orbit configuration is sought that would increase the total time …
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The Effects of Low Earth Orbit Satellite Constellation Altitude and Inclination on Simulated Non-Terrestrial Network Performance
… have varied in scale and architecture. Satellite orbital elements have been a key feature of the ongoing development and design of modern constellations. Orbital altitude and inclination have impacted the types of service and extent of ground coverage each network can provide. The large scale of …
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Graphene Nano-Composites For Hypervelocity Impact Applications
The Low Earth Orbit (LEO) is a harsh environment cluttered with natural meteoroids and man-made debris, which can travel at velocities approaching 15 km/s. Most space activities within the LEO will encounter this environment. Thus, the spacecraft and its hardware must be designed to survive debris …
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Swarm keeping strategies for spacecraft under J2 and atmospheric drag perturbations
… the two main disturbances for spacecraft in Low Earth Orbit (LEO), $J_2$ and atmospheric drag. Using this dynamic model, numerical simulations are provided at each step to show the effectiveness of each method and to see where improvements can be made. The main result is a set of initial …
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Configuration Validation of a Novel In-Space Propellant Storage and Transfer System
… concept of developing a new technology for on-orbit storage and refueling system has been a great interest among scientists for many decades. This study is about Centaur-based on-orbit propellant storage and transfer. This system takes the advantage of rotational settling to a simple fluid …
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Small Satellite Closed Ecosystems as Enabling Platforms for Low-Cost In-Space Biological Research
… for these CubeSats have typically been Earth observation, communication, technology demonstration, or education. Very few CubeSats are launched with biological research payloads, which are typically hosted on larger spacecraft due to the size, weight, and power (SWaP) requirements of …
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Characterization of commercial step-down converter performance in the low Earth orbit radiation environment
… commercial step-down DC-DC converters for the Low Earth Orbit (LEO) space radiation environment. Commercial space industry is shifting spacecraft design philosophy toward accepting more risk for shorter lead times, lower costs, and high instrument performance. This shift opens up the Commercial …
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Analysis of a CubeSat Orbit Using STK
This thesis presents an analysis of CubeSat orbits for both Low Earth Orbit (LEO) and Sun-Synchronous Orbit (SSO) missions using Systems Tool Kit (STK). The study focuses on analyzing communication, power generation, and radiation exposure while considering various factors. The analysis is based on …
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