Browsing by Subject "Spacecraft"

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    The development of a simulator system and hardware test bed for deep space X-Ray navigation
    (2013-09) Doyle, Patrick T.
    Currently, there is a considerable interest in developing technologies that will allow using photon measurements from celestial x-ray sources for deep space navigation. The impetus for this is that many envisioned future space missions will require spacecraft to have autonomous navigation capabilities. For missions close to Earth, Global Navigation Satellite Systems (GNSS) such as GPS are readily available for use, but for missions far from Earth, other alternatives must be provided. While existing systems such as the Deep Space Network (DSN) can be used, latencies associated with servicing a fleet of vehicles may not be compatible with some autonomous operations requiring timely updates of their navigation solution. Because of their somewhat predictable emissions, pulsars are the ideal candidates for x-ray sources that can be used to provide key parameters for navigation. Algorithms and simulation tools that will enable designing and analyzing x-ray navigation concepts are presented. The development of a compact x-ray detector system is pivotal to the eventual deployment of such navigation systems. Therefore, results of a high altitude balloon test to evaluate the design of a compact x-ray detector system are described as well.
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    Simulation and optimization of spacecraft re-entry Trajectories
    (2010-05) Tetzman, Derrick G.
    Parameter optimal control has the advantage of often being easier and faster to solve than general optimal control methods, and may be better suited to the task of spacecraft re-entry trajectory optimization. In this thesis, a parameter optimal control algorithm is implemented in MATLAB® to optimize a 2-D re-entry trajectory simulated via Simulink®. Simulation results are validated by comparison with data from the flight of Apollo 4. Behavior of the algorithm is observed as it optimizes the control input under different conditions without constraints applied. The performance of the optimization program is observed as the complexity of the control input is increased up to the point where constraints are required to continue the optimization process. Finally, a guide is laid out for further development of the algorithm towards both pre-flight trajectory planning and real-time control applications for re-entry.