Date of Award

12-2016

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Aeronautics and Astronautics

First Advisor

James M. Longuski

Committee Chair

James M. Longuski

Committee Member 1

William Crossley

Committee Member 2

Michael Grant

Committee Member 3

Kathleen Howell

Abstract

A method for finding optimal aerogravity-assist tours of the solar system is developed using indirect methods. Two cost functionals are used in the optimization; finding the minimum required maximum lift-to-drag ratio, with and without a convective heating-rate path constraint, and the path which provides the minimum total stagnation point convective heat load. It is found that using present or near-future thermal protection system materials will suffice for certain aerogravity assist trajectories at Mars. Minimum heat load optimal trajectories are found for aerocapture maneuvers at Uranus and Neptune. With a large radius, and short rotational periods, atmospheric rotation must be taken into account to accurately model the system dynamics.

Investigation of the 2018 Inspiration Mars free-return opportunity is conducted. A broad search over 100 years of Mars free-return trajectories is catalogued, and a Pareto front analysis is employed to find the overall best trajectories in the timespan. The geometry is explored further with the use of a time-free ephemeris to see where minimal energy transfer arcs between Earth and Mars occur, and see if the 2018 opportunity is one such transfer. It turned out that both the 2017 and 2064 candidates found from the 100-year search were the closest to minimum energy, highlighting the rarity of the Inspiration Mars opportunity, and gives a motivating push to fly this mission.

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