Date of Award

12-2019

Document Type

Thesis - Open Access

Degree Name

Master of Science in Aerospace Engineering

Department

Aerospace Engineering

Committee Chair

Dr. Morad Nazari

First Committee Member

Dr. Donguen Seo

Second Committee Member

Dr. Richard Prazenica

Third Committee Member

Dr. Troy Henderson

Abstract

The use of Coulomb force has been analyzed in recent years to provide propulsion in space for various applications. Coulomb formation can also be utilized to make close formation spacecraft missions fuel efficient. In this study, the Coulomb formation of two craft is studied in elliptic chief orbits for two formation geometries. The first formation requires both spacecraft to be aligned along the nadir (radial) direction and the second formation requires both spacecraft to maintain a constant separation distance relative to each other while each spacecraft rotates freely on the surface of a sphere with the ratio of the radii being inversely proportional to the ratio of the masses. Two nonlinear optimal feedback control techniques are implemented to stabilize the dynamics of the Coulomb formation and maintain the desired formation while minimizing the energy costs. The control accelerations are compared to the analytical constraint accelerations obtained using the Udwadia-Kalaba equations for constrained motion. Due to the effects of plasma shielding, a Debye length model is incorporated in the nonlinear dynamics as a linear function of altitude of the formation's center of mass. The integrated thruster efforts are calculated for both optimal and analytical techniques and the fuel costs are determined and compared for both formations. The results demonstrated that the use of Coulomb force increases fuel efficiency for formation achievement and maintenance. The numerical analysis is performed on a) the highly eccentric Molniya orbit and b) the near-circular near-GEO orbit of the ERS-21.

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