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Full-Text Articles in Astrodynamics
Orbit Estimation Using Track Compression And Least Squares Differential Correction, Vincent J. Chioma
Orbit Estimation Using Track Compression And Least Squares Differential Correction, Vincent J. Chioma
Theses and Dissertations
This thesis develops two methods of compressing a track of radar observations of a satellite into a single state vector and associated covariance matrix, and a method of estimating orbits using results from multiple tracks. The track compression uses least squares differential correction to determine a state vector at the central observation time. The resulting state vectors and covariance matrices are then used to estimate the satellite's orbit, also using least squares differential correction. Numerical integration using two-body, J2 and an atmospheric drag model is used to represent the dynamics. This orbit estimation produces a state vector which includes …
Optimal Non-Coplanar Launch To Quick Rendezvous, Gregory B. Sears
Optimal Non-Coplanar Launch To Quick Rendezvous, Gregory B. Sears
Theses and Dissertations
The purpose of this study was to determine the feasibility of launching a Delta Clipper-like vehicle on an optimal, non-coplanar trajectory to rendezvous with an earth orbiting object in one orbit or less. The focus of the research was to determine what such a trajectory would look like, and to determine the cost, in payload mass, of flying such a trajectory. A model for the ascent trajectory was developed using the dynamics equations of motion, an atmosphere model, and an aerodynamic model for the DC-Y concept vehicle. A boundary value problem was posed and solved for a coplanar rendezvous. The …
Optimization Of A Nutation Damper Attached To A Spin-Stabilized Satellite, Brady P. Hauboldt
Optimization Of A Nutation Damper Attached To A Spin-Stabilized Satellite, Brady P. Hauboldt
Theses and Dissertations
This study uses linearized equations of motion for a rigid body with an attached spring-mass-damper to maximize the decay rate of a satellite's coning motion. An analysis of the numerical eigenvalues is presented which leads to an optimal relationship between relevant parameters: damper placement, spring constant, damping coefficient, system moments of inertia, and damper mass fraction. The coupled system's eigenvalues do not provide truly critical damping, thus the real eigenvalue parts are minimized in order to achieve damping which requires the minimum amount of time. A comparison between this optimal design method and a classical method concludes a noticeable improvement …
Modal Control Of An Unstable Periodic Orbit, William Wiesel, William Shelton
Modal Control Of An Unstable Periodic Orbit, William Wiesel, William Shelton
Faculty Publications
We apply Floquet theory to the problem of designing a control system for a satellite in an unstable periodic orbit. Expansion about a periodic orbit produces a time periodic linear system, which is augmented by a time periodic control term. We show that this can be done such that a) the application of control produces only inertial accelerations, b) positive real Poincare exponents are shifted into the left half-plane, and c) the shift of the exponent is linear with control gain. We apply these developments to an unstable orbit near the Earth-Moon L3 point perturbed by the Sun. Finally, …