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Dissertation Defense
Exploration and Optimization of Low-Energy Capture Options at Jovian Moons
Kevin A. Bokelmann
PhD Candidate
Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin
Friday, August 10, 2018, 10:00 am
WRW 410

A key trade-off for planetary system exploration is the fuel cost required versus science data obtained. Historically, planetary systems have been explored utilizing multiple flybys, such as Cassini and the proposed Europa Clipper mission. An alternative that seeks to maximize science return is to capture about each moon of interest. Investigations of low-energy dynamics have shown the existence of relatively inexpensive transfers between halo orbits at different moons. Chaining these transfers in a moon-hopping tour allows one spacecraft to visit multiple moons. The next step is to connect inter-moon transfers to science orbits for a complete end-to-end transfer.

This dissertation develops the methods used to generate and optimize these impulsive transfer trajectories to capture at Europa using a combination of analytical and numerical techniques. The problem is approached in three major steps: connecting halo orbits to different classes of science orbits, optimization using primer vector theory, and connecting the optimized transfer to the last resonant orbit of a Europa approach trajectory.  Key challenges addressed include determining the “goodness” of initial guesses, efficiently connecting orbits in three-dimensional space, and mitigating the effects of hyper-sensitive trajectories.

As an additional mission design option, the possibilities of advanced exploration using an electrodynamic tether are investigated. An approximation to the tether-perturbed dynamics is derived that allows for an integral of motion, enabling useful analytical techniques. New periodic orbit families are generated as a function of tether length, using continuation from non-perturbed Lyapunov orbits. The new orbits are analyzed in terms of stability and utility for future use in mission design.

Contact  Dr. Ryan Russell ryan.russell@austin.utexas.edu OR (512) 471-4190

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