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- Artificial satellites--Orbits (2)
- Artificial satellites--Orbits--Mathematical models (2)
- Artificial satellites--Control systems (1)
- Artificial satellites--Orbits--Effect of radiation pressure on (1)
- Drag (Aerodynamics)--Mathematical models (1)
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- Genetic algorithms (1)
- Geostationary satellites (1)
- Military communications (1)
- Near-earth asteroids (1)
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- Orbital mechanics (1)
- Orbital transfer (1)
- Radiation pressure (1)
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- Space flight to asteroids (1)
- Space surveillance (1)
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- Trajectories (1)
Articles 1 - 7 of 7
Full-Text Articles in Astrodynamics
Optimization Of Active Rendezvous Trajectories By Genetic Algorithms, Marie Emmanuelle Ricour
Optimization Of Active Rendezvous Trajectories By Genetic Algorithms, Marie Emmanuelle Ricour
Master's Theses - Daytona Beach
Trajectory optimization is and will remain a hot topic in the engineering field. Because analytical or exact solutions are often difficult and sometimes impossible to compute, there is a need for alternative and efficient methods. UnderWater Vehicles (UWV) trajectories and rendezvous trajectories of continuous low-thrust spacecraft are examined. One of the methods to solve such problems is the Genetic Algorithm (GA) method. In this work, a GA has been developed using Matlab®. It treats possible solutions to the studied problems as individuals and eventually converges to an optimal or near optimal solution. Genetic Algorithms have been used previously to solve …
Spacecraft Trajectory Design For Short Duration Near Earth Asteroid Missions, Synthia Mirlin Findlay
Spacecraft Trajectory Design For Short Duration Near Earth Asteroid Missions, Synthia Mirlin Findlay
Mechanical & Aerospace Engineering Theses & Dissertations
Design of orbital trajectories using patched conic approximation methodology for short duration missions to newly detected, incoming near Earth asteroids, which are on close approach trajectories with Earth, is the focus of this thesis. The primary purpose for such missions is two fold. First, near Earth asteroids provide unique mission opportunities for solar system science where the celestial body of interest transits to Earth proximity and is studied in situ by probes having short duration trajectories, rather than sending long distance probes to the celestial body. Second, improved characterization of asteroid properties, compositions, and orbital states for reduction of uncertainties …
Maneuver Estimation Model For Geostationary Orbit Determination, Brian J. Hirsch
Maneuver Estimation Model For Geostationary Orbit Determination, Brian J. Hirsch
Theses and Dissertations
As an increasing number of geostationary satellites fill a limited number of orbital slots, collocation of satellites leads to a risk of close approach or misidentification. The ability to detect maneuvers made by these satellites using optical observations can help to prevent these problems. Such a model has already been created and tested using data from the Air Force Maui Optical and Supercomputing site. The goal of this research was to create a more robust model which would reduce the amount of data needed to make accurate maneuver estimations. The Clohessy-Wiltshire equations were used to model the relative motion of …
The Effects Of Using Solar Radiation Pressure To Alleviate Fuel Requirements For Orbit Changing And Maintenance Of The Dscs Ii F-13 Satellite, Jody A. Paris
Theses and Dissertations
Orbit disposal and maintenance of aging satellites has become a significant concern over the past few years, as the increasing number of orbiting objects threatens to limit the launching of future satellites. Many of the satellites currently in orbit, however, were not built with disposal considerations. The DSCS II series was launched into orbit beginning in the 1970s, and many satellites are now without the fuel required to conventionally transition to a sanctioned disposal orbit. In GEO orbit the largest non-gravitational perturbation is solar radiation pressure. By adjusting the attitude of a satellite with a controller to maximize the perturbing …
Covariance Estimation And Autocorrelation Of Norad Two-Line Element Sets, Victor P. Osweiler
Covariance Estimation And Autocorrelation Of Norad Two-Line Element Sets, Victor P. Osweiler
Theses and Dissertations
This thesis investigates NORAD two-line element sets (TLE) containing satellite mean orbital elements for the purpose of estimating a covariance matrix and formulating an autocorrelation relationship. Orbit propagation is performed using Simplified General Perturbations Number 4 (SGP4) analytical model as implemented within Satellite Took Kit. For a given satellite, TLEs from a span of two weeks are used to calculate position and velocity differences of estimated state vectors in order to characterize their variance behavior and compute a covariance matrix for the most recent TLE. Six satellites and eight time spans are investigated, with all state vector differences evaluated in …
Characterizing And Controlling The Effects Of Differential Drag On Satellite Formations, James T. Wedekind
Characterizing And Controlling The Effects Of Differential Drag On Satellite Formations, James T. Wedekind
Theses and Dissertations
The ability to fly satellites in close formations represents a capability that could revolutionize the way satellite missions are designed in the future. This study examines three of the primary formation flying designs and characterizes the effects that an anomalous satellite with a slightly different cross-sectional area would have on the stability of the formation. Following the characterization of these effects, a controller is implemented to mitigate the cross-sectional area differences between the satellites. The results show that, with the addition of a straightforward controller, small cross-sectional area differences can be mitigated and corrected such that the satellites will remain …
Optimal Coverage Of Theater Targets With Small Satellite Constellations, Axel Rendon
Optimal Coverage Of Theater Targets With Small Satellite Constellations, Axel Rendon
Theses and Dissertations
The daylight passes of a low-Earth orbit satellite over a targeted latitude and longitude are optimized by varying the inclination and eccentricity of an orbit at different altitudes. This investigation extends the work by Emery et al, in which the optimal Right Ascension of the Ascending Node was determined for a circular, matched inclination orbit. The optimal values were determined by a numerical research method based on Emery et al's Matlab program. Results indicate that small increases in inclination raise the number of daylight passes up to 33%. These optimal inclinations depend on the satellite semi-major axis. Eccentricity increases also …