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Full-Text Articles in Engineering
Applications Of Aerodynamic Forces For Spacecraft Orbit Maneuverability In Operationally Responsive Space And Space Reconstitution Needs, Matthew N. Goodson
Applications Of Aerodynamic Forces For Spacecraft Orbit Maneuverability In Operationally Responsive Space And Space Reconstitution Needs, Matthew N. Goodson
Theses and Dissertations
Each year multiple satellites are launched to provide end users key pieces of information. This information ranges from remote sensing data for military or civilian purposes (e.g., weather forecasting, troop movements, agricultural production, etc.) to large bandwidth telecommunications sensors. No matter the type of information needed, society is demanding more. Because of this continual rise in information needs, the current model of launching one satellite for one mission is not sustainable. To satisfy the information needs of nations across the globe, a means for satellites to transition from one mission type to another must be developed. One means of transitioning …
Application Of Kam Theorem To Earth Orbiting Satellites, Bryan D. Little
Application Of Kam Theorem To Earth Orbiting Satellites, Bryan D. Little
Theses and Dissertations
An orbit that lies on a Kolmogorov, Arnold, and Moser (KAM) Torus will remain on that torus until and unless it experiences a force that causes it to leave the torus. Earth satellites that are subject only to the Earth's gravity field may lie on such KAM tori. Analyzing on orbit satellite position data should allow for the identification of the fundamental frequencies needed to define the KAM tori for modeling Earth satellite orbits. KAM Tori are created for the Gravity Recovery and Climate Experience (GRACE) and Jason-1 satellites to model their orbital motion. Precise position data for the satellites …
Initial Determination Of Low Earth Orbits Using Commercial Telescopes, Matthew M. Schmunk
Initial Determination Of Low Earth Orbits Using Commercial Telescopes, Matthew M. Schmunk
Theses and Dissertations
Within the last decade, many new technologies have significantly changed the face of private astronomy. Developments such as inexpensive but high-quality sensors, rapid personal computing, and easy networking inspire a reexamination of an old problem: how practical is it to develop initial orbit estimates for Low Earth Orbiting (LEO) satellites using optical tracking? This paper documents the design and implementation of a commercial telescope system used to answer precisely that question. This analysis deter- mined there are some challenging barriers to successful single-site orbit determination, but it is possible given the right conditions. Considering the low cost and small sup- …
Optimal Orbital Coverage Of Theater Operations And Targets, Kimberly A. Sugrue
Optimal Orbital Coverage Of Theater Operations And Targets, Kimberly A. Sugrue
Theses and Dissertations
The use of satellites as a tactical asset to support theater operations is a desired capability for future space operations. Unlike traditional satellite systems designed to provide coverage over the entire globe or large regions, tactical satellites would provide coverage over a small region which can be modeled as a single ground point defined by a latitude and longitude. In order to provide sufficient utility as a theater asset, a satellite should be placed in an orbit that provides a maximum amount of coverage of the target ground point. This study examined the optimization of orbit parameters to maximize the …
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 …
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 …
Mean Performance Optimization Of An Orbiting Distributed Aperture By Warped Aperture Image Plane Comparisons, Timothy W. Parker
Mean Performance Optimization Of An Orbiting Distributed Aperture By Warped Aperture Image Plane Comparisons, Timothy W. Parker
Theses and Dissertations
This work models the aggregate performance of satellite receiver formations functioning as orbiting interferometers as compared to filled apertures of similar geometries. These models facilitate selecting initial conditions for formations such that their control-free dynamics yield interferometry performance with minimal errors as compared to the filled apertures. The solution method draws on the dynamic models of an orbiting planar satellite formation to define the size and shape of a reference aperture and to define the degrees of freedom for the formation members. The paths of formation elements yield geometries for which the aggregate performance of the array of discrete receivers …
Solar Radiation Pressure Modeling Issues For High Altitude Satellites, Dayne G. Cook
Solar Radiation Pressure Modeling Issues For High Altitude Satellites, Dayne G. Cook
Theses and Dissertations
Current satellite orbit propagation techniques employ a solar radiation pressure model that makes simplifying assumptions concerning the satellite and its orbital geometry. Solar radiation pressure, a non-gravitational perturbation, significantly affects satellite motion at high altitudes. The model currently in use by the Air Force for orbit determination includes the following assumptions: a constant cross-sectional area projected to the Sun, cylindrical Earth shadow for eclipse, and specular reflection. In reality, the satellite's cross-sectional area with respect to the Sun constantly changes, the Earth's shadow is conical, and reflection is both specular and diffuse. Additionally, the solar flux received at the Earth …
Relative Equilibria Of A Rigid Satellite In A Central Gravitational Field, Jeffrey A. Beck
Relative Equilibria Of A Rigid Satellite In A Central Gravitational Field, Jeffrey A. Beck
Theses and Dissertations
We apply noncanonical Hamiltonian methods to examine relative equilibria of a rigid body in a central gravitational field. These equilibria correspond to fixed points of a reduced set of equations expressed in a rotating frame and are representative of an orbiting satellite with fixed attitude relative to an observer rotating at the orbital rate. Our objective is to clarify the relationship between the classical approximation and a recent noncanonical Hamiltonian treatment. In contrast to the classical approximation, the orbital and attitude equations of motion for the noncanonical system remain coupled and the general solution is a circular orbit for which …