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Nathan Harl
Missouri University of Science and Technology
Advisor: Henry J. Pernicka
Abstract
A method is presented for establishing and maintaining a lunar mapping orbit using continuous low-thrust propulsion. Optimal control theory is used to maintain a lunar orbit that is low-altitude, near-polar, and Sun-synchronous, which are three typical requirements for a successful lunar mapping mission. The analysis of the optimal control problem leads to the commonly seen two-point boundary value problem, which is solved using a simple indirect shooting algorithm. Simulations are presented for a one-year mapping duration, in which it is shown that a very tight control is achieved with thrust levels below 0.7 N for a 1000 kg spacecraft.
Nathan Harl is currently a Ph.D. student at the Missouri University of Science & Technology in Rolla, MO, graduating Suma Cum Laude with both his bachelor's degree in 2005, and his Master's degree in 2007. He is pursuing the field of Aerospace Engineering with an emphasis on orbital mechanics and low-thrust control methods. Nathan's career goal is to one day work at NASA in a position related to orbital guidance and control. Nathan is currently a member of AIAA and the Sigma Gamma Tau honor society.
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