Date of Award

3-2007

Document Type

Thesis

Degree Name

Master of Science in Astronautical Engineering

Department

Department of Aeronautics and Astronautics

First Advisor

Nathan A. Titus, PhD

Abstract

Satellite formations, otherwise known in the space community as satellite clusters or distributed satellite systems, have been studied extensively over the last 10 to 15 years. For use in remote sensing applications, formations consisting of smaller, simpler satellites provide numerous advantages over individual satellites. The image resolution capabilities of small-satellite formations constitute a significant technological leap in the ability to synthesize critical information. This research utilizes the nonlinear satellite dynamics, including gravitational perturbations, to search for the optimal fuel cost for maintaining a circular formation. The system dynamics were developed in an earth-centered inertial coordinate frame using the methods of Hamiltonian dynamics. Continuous dynamic optimization theory was used to minimize fuel requirements, resulting in a continuous thrust, open-loop control law. The uncontrolled reference trajectory off which the formation is based was restricted to a circular, inclined orbit. Given initial conditions which match the mean motion of every member of the formation, it is shown that 1-km circular formation configurations can be maintained for control costs on the order of 40-50 m/s/year at an altitude of 400 km. Additionally, further fuel savings are possible with modifications to orbit altitude, formation radius, and variations in the defined performance index.

AFIT Designator

AFIT-GA-ENY-07-M02

DTIC Accession Number

ADA469270

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