The Dynamics And Control Of Flux-Pinned Space Systems: Theory And Experiment

Abstract

Advanced space systems are increasingly reliant on close-proximity operations to achieve complex mission objectives on orbit. These maneuvers - such as docking and rendezvous, formation flying, and on-orbit assembly, refit, and repair - require spacecraft that can provide robust, stable, and predictable behavior. Flux -pinned interfaces (FPIs) for spacecraft are a developing technology that addresses these growing demands on the capabilities and reliability of space systems by exploiting the physics of magnetic flux pinning. Flux pinning is a phenomenon in superconducting physics involving type II superconductors cooled below their critical temperature in the presence of a magnetic field. When set up correctly, the superconductor resists changes to the distribution of magnetic flux present during the temperature transition. The resulting physics passively "pins" a magnetic field source in a six-degree-of-freedom equilibrium relative to the superconductor. By using this interaction to influence the dynamics between spacecraft, an FPI can provide stiff, stable, and controllable relative equilibrium points between magnets on one spacecraft and the superconductors on the other. This dissertation details the extensive research and development work on fluxpinned interfaces for spacecraft. In addition to describing the concepts and literature relevant to the technology, this document examines the modeling, actuation, and control strategies that provide the theoretical grounding for designing FPIs. Going beyond mathematical foundations, subsequent sections explain the results from FPI technology development efforts in laboratory and microgravity experimental environments. The concluding chapters address the practical considerations an orbital FPI design and the prospects for the technology as a whole.