Dynamics and Control of Tethered Satellite Formations for the Purpose of Space-Based Remote Sensing

摘要

This dissertation assesses the utility of tethered satellite formations for the space-based remote sensing mission. Energy dissipation is found to have an adverse effect on foundational rigid body (Likins-Pringle) equilibria. It is shown that a continuously earth-facing equilibrium condition for a fixed-length tethered system does not exist since the spin rate required for the proper precession would not be high enough to maintain tether tension. The range of required spin rates for steady-spin motion is numerically defined here, but none of these conditions can meet the continuously earth-facing criteria. Of particular note is the discovery that applying certain rigid body conditions to a free-flying formation creates the desired equilibrium condition. Control methods applied to the tethered system fail to maintain formation orientation or are cost prohibitive. The overall assessment is that tethers have great value for general formations, however, by themselves tethers cannot conduct formation control for continuously earth-facing aperture clusters. Even with additional controls, the utility of tethers for this mission is limited.