Date of Award

12-1995

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Aeronautics and Astronautics

First Advisor

Christopher D. Hall, PhD

Abstract

The purpose of this research is to understand and describe the process by which the 1986 Polar BEAR gravity- gradient research satellite of John Hopkins University/Applied Physics Laboratory achieved an orbital attitude correction (re-inversion) from an inverted orientation through the utilization of its momentum wheel. Understanding this process provides an analytical foundation from which a universal attitude inversion process for other gravity-gradient satellites with similar anomalous motions may be sought and developed. The equations of motion for a gravity-gradient satellite with a momentum wheel are derived and implemented in FORTRAN for simulation of the dynamics of the spacecraft. Several re-inversion characteristics are observed, in particular, the dynamics about the pitch axis. The resulting observations demonstrate an unexpected non-linear relationship between the oscillation angle of the pitch axis and the despin time of the momentum wheel. This phenomenon depends in part on the size of the momentum wheel compared to that of the spacecraft and on the pitch angle at the time of motor torque application.

AFIT Designator

AFIT-GSO-ENY-95D-02

DTIC Accession Number

ADA303238

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