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Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Real-time navigation during the final approach phase of an interplanetary mission can significantly increase the accuracy of aerocapture and pin-point landing. The Mars Network is a versatile telecommunications network that is ideally situated to provide spacecraft-to-spacecraft radiometric navigation during Mars final approach and entry, descent, and landing via the Electra UHF transceiver, which is capable of providing autonomous, on-orbit, real-time trajectory determination using two-way Doppler measurements between a Mars approach vehicle and a Mars Network orbiter. A detailed dynamic analysis and link analysis of the final approach problem is presented, which seeks to determine the expected operating conditions of the Electra transceiver. In particular, the maximum Doppler shift and Doppler rate, which determine the transceiver tracking loop requirements, and the total received signal power and signal-to-noise ratio, which determine the range at which the communications link can be closed, are investigated for a range of Mars Network orbital geometries. A model of the Electra signal is developed on the basis of the results of the dynamic analysis and link analysis and is used as input to a high-fidelity simulation of the Electra transceiver. A Monte Carlo analysis is performed to determine the performance of the Electra transceiver for a range of signal and tracking loop parameters. In particular, the performance analysis focuses on the maximum range at which the link can be closed and on the acquisition and tracking performance of the second-order tracking loop. The analysis of the tracking performance is used to characterize and model the error in the Doppler measurement of the Electra transceiver. The error model is incorporated into the design of an extended Kalman filter, in order to improve the fidelity of the navigation filter design. The information content in the Doppler measurement and the observability of the estimated states are investigated for various orbital geometries and the accuracy of the navigation solution is analyzed.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

There are critical questions we must engage in before we ever set foot or flag on Mars. Why do we go? How do we convince ourselves it is worth it? In this work, I will analyze the current discourse of Mars. Mars is legitimized as a place through a form of discourse whose roots can be traced back to earlier, colonial forms of discourse. Modernity acts as a normative force by limiting our language to established forms of discourse, like Hegelian notions of progress, while marginalizing other possibilities of narrative. The colonial gaze is only one possible way we have to understand Mars. What is necessary now is to perform the great Foucaultian task of seeking out lost narratives and lost knowledges of our past. I will examine how the power of narrative has been used to convince the public that we should go to Mars. Modernity has phenomenologically shaped Mars and our present discourse of Mars is the result of that metamorphosis. Narratives of science-fiction, science advocacy, special interest groups, and government bureaucracy reflect the modern notions that pervade Areological discourse, thereby promoting a colonial gaze of Mars. Modernity represents a way of seeing Mars that has been pushed upon us by history, eliminating alternate narratives of place through the nonnative practice of modern thinking.

Thesis (M.S.)--Mississippi State University. Department of Aerospace Engineering. / Title from title screen. Includes bibliographical references.

The International Space Station utilizes many different forms of written and verbal communication between the flight crews and ground control personnel. This study analyzes the historical use of three regular communication methods, Daily Planning Conferences, Weekly Planning Conferences and written Daily Summaries, as well as specific, science and internal maintenance events for characteristics and perceived effectiveness across eight expeditions (4 ? 11). The results are recommendations for the continued use of, or substitution for, these methods for future long-duration human space missions, specifically to the Moon and to Mars. General conclusions are that most of the conference content could have been relayed through written/electronic methods, and that the Daily Summaries are considered succinct and effective as a communication cornerstone. Conclusions formed from the study of individual events involved the importance of well-written crew procedures, the effective stowage and retrieval of necessary materials and the selection of well-defined science experiments.