Accession Number : ADA303238

Title :   Analysis of Gravity-Gradient Satellite Attitude Inversion.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING

Personal Author(s) : Desamours, Jules-Francois D.

PDF Url : ADA303238

Report Date : DEC 1995

Pagination or Media Count : 65

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.

Descriptors :   *SATELLITE ATTITUDE, *ATTITUDE(INCLINATION), MATHEMATICAL MODELS, ALGORITHMS, COMPUTERIZED SIMULATION, STABILITY, OPTIMIZATION, ATTITUDE CONTROL SYSTEMS, PITCH(INCLINATION), PITCH(MOTION), YAW, EQUATIONS OF MOTION, EARTH ORBITS, ORIENTATION(DIRECTION), THESES, GRAVITY, INVERSION, SPINNING(MOTION), NONLINEAR ANALYSIS, TORQUE, ANGULAR MOMENTUM, MOMENT OF INERTIA, SCIENTIFIC SATELLITES.

Subject Categories : Spacecraft Trajectories and Reentry

Distribution Statement : APPROVED FOR PUBLIC RELEASE