Ph.D. Thesis Defense

Madilyn Drosendahl-Birbasov

(Faculty Advisor: Professor Dimitri Mavris)

"A Methodology for the Optimization of Hybrid SEP-Chem Trajectories for Outer Planets Missions"

Tuesday, April 21

12:00 p.m.

Weber II CoDE 

Abstract: 

In space mission planning, trajectory analysis is broadly treated like an optimization problem consisting of two categories: sequence optimization, and path optimization. When solving this problem within the context of interplanetary low-thrust trajectories, there is a noticeable tradeoff between solution quality and computational speed, with priority broadly given to speed at early design stages. This prioritization is understandable when the goal is mission feasibility, but it can cause issues with the resulting solution set at later points in the design process. The inclusion of sequence optimization is variable and may be inefficient. High performing solutions may be incorrectly labeled as infeasible due to sparse, random sampling of the design space and prematurely removed from consideration. Path optimization in particular is less of a unified approach, and more a collection of ad hoc methods designed for very specific missions at hand.

The research detailed in this thesis aims to challenge some of the preexisting methods for performing low-thrust space mission planning with the aims of increasing computational efficiency and solution set optimality. The first goal of this research aims to compare the computational efficiency of a state-of-the-art genetic algorithm powered solution optimizer against a simpler pruned factorial method. The second goal aims to measure the impact of starting or “initial guess” methods in the path optimization problem across fidelity levels. The third goal aims to investigate the lack of fully global optimization methods for low-thrust interplanetary trajectories despite their commonality in high-thrust applications.

Committee:

Dr. Dimitri Mavris (advisor), School of Aerospace Engineering
Prof. Brian Gunter, School of Aerospace Engineering
Prof. Graeme Kennedy, School of Aerospace Engineering
Dr. Bradford Robertson, School of Aerospace Engineering
Dr. Stephen Edwards, NASA Marshall Space Flight Center