John Shepard

Date of Award

January 2020

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Space Studies

First Advisor

Fevig Ronald

Abstract

The required change in velocity for a satellite to change inclination has prompted studies of efficient orbital transfers. Modeling the motion of a spacecraft by including the gravitational forces associated with the Sun, Earth, and Moon has historically proven effective in obtaining new scientific knowledge. In modeling the motion of satellites, the circular restricted three body problem (CR3BP) demonstrates the interactions from two primary bodies and a satellite. The dynamics created about the equilibrium points within the CR3BP can be used to construct low-energy transfers. The invariant manifolds of the libration point orbits (LPO) can be used to create an orbit using a weak stable boundary (WSB) to approach a coplanar Lagrange point. Following the use of two distinct libration point orbits a satellite can adjust for a return at a greater difference of inclination compared to a one impulse maneuver. On approach to the second Lagrange point, the satellite follows a horizontal Lyapunov orbit to use another maneuver placing the satellite in a vertical Lyapunov orbit. Following the vertical Lyapunov orbit the weak unstable boundary is used for a return toward Earth at a different inclination. Given the trajectory created, a 90-degree inclination change has been developed. The maneuver cost is compared to a Hohmann transfer and bi-elliptic transfer for a decrease in fuel as well as an increase in the time of flight. An analysis of the periodic orbital transfer created in this research is performed, as well as other orbits from associated research articles suggest that a significant amount of velocity savings can be achieved. Continuing with the use of such constructed trajectories, a brief investigation on to financial and environmental impacts are also reviewed. The result of this study demonstrates the utility of periodic orbital transfers and their importance in mission design for plane change maneuvers.

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