Date of Award

8-2014

Degree Name

Master of Science

Department

Mechanical and Aerospace Engineering

First Advisor

Dr. Jennifer Hudson

Second Advisor

Dr. James Kamman

Third Advisor

Dr. Kapseong Ro

Fourth Advisor

Dr. Christopher Cho

Keywords

Trojan asteroids, dynamic program, optimization, GMAT, Matlab

Access Setting

Masters Thesis-Open Access

Abstract

The problem of finding a minimum-fuel trajectory for a mission to the Jovian Trojan asteroids is considered. The problem is formulated as a modified traveling salesman problem. Two different types of algorithms such as an exhaustive search algorithm and a serial rendezvous search algorithm are developed. The General Mission Analysis Tool (GMAT) is employed for finding optimum trajectories with minimal fuel consumption. The selection of a minimum-fuel mission trajectory, and the associated target asteroids, will be a key factor in determining feasibility and scientific value of a Trojan tour and rendezvous mission.

The transfer trajectory followed by a spacecraft between two orbital states can be calculated by solving Lambert’s problem. Matlab language is extensively used to establish the intercommunicating interface between GMAT software and Lambert’s solution. The results achieved by solving Lambert’s problem and dynamic programming algorithm in Matlab are directly passed to GMAT software for higher-fidelity trajectory optimization and visualization of the trajectory. The comparison between the results obtained is verified by minimum delta-v criteria.

In this thesis several cases of asteroid selection are taken into consideration. An exhaustive search approach, which considers every possible permutation of the order of asteroid visits, is employed up to the practical limit of eight asteroids. A larger number of Trojan asteroids sets require more efficient methods; a serial rendezvous search is employed for larger sets. Also a range of mission dates and transfer times are considered.

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