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Thesis (Ph. D.)--University of Texas at Austin, 2003. / Supervisor: Jeffrey D. Vaaler. Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (M.Sc.). / Written for the Dept. of Physics. Title from title page of PDF (viewed 2008/12/04). Includes bibliographical references.

The historical method of precise orbit determination is a dynamic approach. However, with the improvement of GPS tracking data and associated tracking networks, two newer methods have been developed: reduced-dynamic and kinematic. In addition to orbit determination, alternative methods of gravity field recovery have been developed using kinematic orbits which do not rely on any force modeling. However, one significant drawback of kinematic orbits is that they lack any velocity or acceleration information. These have to be derived numerically. Based on the results of this thesis, the Savitzky-Golay filter, without using a remove-restore procedure, is recommended for deriving kinematic velocities of the GRACE mission. In addition, the numerical differentiation methods are tested to see how well accurately they represent the satellite's acceleration for all three orbit types. Finally, with the kinematic orbits properly reconstructed, the results can also be compared to dynamic and reduced-dynamic orbits through K-Band Ranging residuals. / text

Thesis(M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (p.35-36).

Thesis (M.S.)--California Polytechnic State University, 2009. / Title from PDF title page; viewed on January 8, 2009. Major professor: Jordi Puig-Suari, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Aerospace Engineering." "July 2009." Includes bibliographical references (p. 70-71). Will also be available on microfiche.

This work presents a measurement model designed for multiple observers (space-based and/or ground-based) for cislunar orbit determination and estimation for space domain awareness (SDA). The measurement model is able to rely solely on angles-only measurements by defining the line between the observer and the target object as the intersection of two non-parallel planes. There are two primary applications for the measurement model related to cislunar SDA: (1) It provides a new initial orbit determination (IOD) technique that does not require any knowledge of the dynamical environment, and (2) It is adopted into a sequential estimation scheme to provide continuous orbit tracking. The present measurement model is studied and demonstrated for both Earth orbits and cislunar space applications. While the goal is to operate in cislunar space, evaluating the measurement model in Earth orbits allows for the comparison against established IOD and estimation methods, resulting in a more rigorous analysis of the performance. Within this work, several different aspects of the present measurement model are studied, both analytically and computationally, to understand their effect on the orbit determination and estimation problems. By methodically varying the location of the observers, relative to the target, it is shown that the error produced by the IOD solution to the measurement behaves in a predictable manner. The IOD solution model can then be compared against similar IOD methods for Earth orbit. For orbit estimation, the measurement model is used in a modified extended Kalman filter that incorporates Analytic Continuation, allowing it to propagate the perturbed orbit dynamics to increase estimation accuracy. The measurement model is then incorporated in both an extended Kalman filter and unscented Kalman filter, comparing the resulting accuracy and computational time as the measurement frequency and nonlinearity of the dynamics are varied. For cislunar space, the measurement model is used to perform IOD and tracking of objects in orbits with relevance to future space missions. Finally, the present measurement model is shown to be capable of fusing other measurement methods from heterogeneous sensors to perform accurate orbit estimation. Overall, it is shown that the measurement model produces highly accurate results for IOD and orbit estimation. The results of the IOD solution have the same level of accuracy as other Earth orbit IOD methods and is shown to be able to easily translate to cislunar orbits without any modification, while maintaining that accuracy. For orbit estimation, the measurement model is shown to converge to an accurate estimate quickly and maintain that level of accuracy even in the absence of measurements, which is to be expected due to the vastness of cislunar space. The present approach will have future applications in space-based space surveillance networks for on-orbit cislunar SDA operations.

An autonomous, real-time orbit determination system was developed within thiswork for the next iteration of the University of W¨urzburg’s CubeSat programme.The algorithm only made use of magnetometer and sun sensors, which already wereimplemented on UWE-3, the third satellite in the programme. Previous developedsystems used the same approach, however the unique aspect in this work is thatthe algorithm was implemented using equinoctial elements.A Runge-Kutta-4 integrator propagated the orbit position using the orbit dynamicsunder the consideration of J2-perturbations. Afterwards, an Extended KalmanFilter corrected the position through processing the two measurements.The algorithm was then tested under multiple conditions. At first, a two weekstability test was conducted using simulated data, followed by a test with recordedsatellite data. These have shown a mean error of 13.2 km and 12.6 km respectively.Lastly, the algorithm was translated in to C and evaluated on a micro-controller.

This thesis demonstrates that any individual can provide relevant observational data to further research efforts within the Aerospace community, through the use of amateur telescopes. A Meade LX200 12 in. telescope and Lumenera Skynyx 2.0 camera were utilized to observe small LEO satellites, using a well-documented point-and-wait staring method. Over a period of three months, a total of 186 observation attempts were made resulting in 97 successful captures. From the gathered data, three possible aerospace applications were analyzed: validation of a satellite brightness prediction model, angles-only orbit determination including extended Kalman filtering, and temporal error growth in TLE-based orbit propagation. Further investigations include a preliminary optimization using MATLAB's fmincon function (informed by the previous analyses) to determine an optimal telescope size for performing LEO observations.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 174-186).