Ph.D. Defense
Kwonhee Alex Lee
(Advisor: Prof. Brian C. Gunter)
"Leveraging Optical Clocks and Relativistic Geodesy for Multi-Satellite Missions and Deep Space Navigation"
Thursday, October 24
10:00 a.m.
Montgomery Knight Building 317
Abstract
The study of gravity throughout history has shed light on a wide range of scientific disciplines, from fundamental physics like Einstein's theory of gravity to planetary geodesy, that influence many aspects of human life today. Despite its rich history, the study of gravity could further benefit from new opportunities enabled by technological advancements. Multi-satellite missions, which provide distributed, robust, and flexible sensor systems, are becoming increasingly feasible due to the advancement in small satellite technologies and reduced launch costs. Additionally, with the advancement of optical clocks, relativistic geodesy, a concept that utilizes gravitational redshift described in Einstein's theory of gravity for gravity modeling, is envisioned to offer a novel approach to observing gravity. This dissertation aims to develop methodologies for designing and operating a multi-satellite geodesy mission that utilizes relativistic geodesy, as well as for navigating a satellite in deep space by reversing the process of relativistic geodesy. The first contribution is the new assessment of the optimized design of multi-satellite geodesy missions, leveraging genetic algorithms and relativistic geodesy observables. Non-symmetric satellite constellations optimized by genetic algorithms are shown to generate short-term, large-scale gravity products that are complementary to other satellite geodesy missions. The second contribution is the development of a deep reinforcement learning framework for autonomous operation of a reconfigurable multi-satellite planetary gravity mission. The trained satellites can collaborate to achieve the mission objective, highlighting the potential of deep reinforcement learning for more efficient and adaptive operations of future multi-satellite planetary gravity missions. The third contribution is a comprehensive analysis on the feasibility of navigating a deep space mission by reversing the process of relativistic geodesy, in which the state is estimated from the known gravitational potential. While there are some limitations, the results show that the proposed approach could potentially complement the deep space network for future deep space missions.
Committee
- Prof. Brian C. Gunter – School of Aerospace Engineering (advisor)
- Prof. E. Glenn Lightsey – School of Aerospace Engineering
- Prof. Koki Ho – School of Aerospace Engineering
- Prof. John Christian – School of Aerospace Engineering
- Dr. Powtawche Valerino – NASA Marshall Space Flight Center