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Full-Text Articles in Astrodynamics
Full Lyapunov Exponent Placement In Reentry Trajectories, Michael H. Platt
Full Lyapunov Exponent Placement In Reentry Trajectories, Michael H. Platt
Theses and Dissertations
This study investigated the ability to control the chaotic reentry of a Delta-Clipper like vehicle by setting the values of initial arid final principal dynamical directions as well as the Lyapunov exponents. A model of the original controlled reentry vehicle was created through the use of the equations of motion in conjunction with an atmospheric model. A modified linear quadratic regulator allowed the set up of a boundary value problem which specified the Lyapunov exponents and determined the gain matrix as a function of time. The gain matrix can eventually be used in the control system of the vehicle.
Analysis Of Gravity-Gradient Satellite Attitude Inversion, Jules-Francois D. Desamours
Analysis Of Gravity-Gradient Satellite Attitude Inversion, Jules-Francois D. Desamours
Theses and Dissertations
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 …