Characterization of a flux-pinning interface for the control of nanosatellites in very close proximity

In this work, we propose a system ensuring autonomous station-keeping of a prescribed configuration of two, or more satellites, in very close proximity, which is realized equipping one satellite with a type-II high temperature superconductor and the other one with a magnet. It is known that the interaction between two magnets can generate either a repulsive or an attractive force, differently a type-II superconductor and a magnet can show an interaction based on the flux-pinning effect and are therefore named a flux-pinning interface (FPI). The force exchanged by the FPI switches from attractive to repulsive as the two devices approach, therefore it allows binding the relative motion of the satellites while ensuring collision avoidance. To establish the flux-pinning effect, the superconductor must be cooled-down below its critical temperature, a process that can be performed by a passive thermal control system. The magnetic characterization of the type-II superconductor, in a sample of granular ceramic YBCO, is performed using a vibrating sample magnetometer. Once characterized the high temperature superconductor, a model of the FPI is and an extension of the Hill-Clohessy-Wiltshire equations is developed. Analysis on the dynamics on the problem allows identifying new equilibrium conditions existing for the FPI and some cases of interest are investigated numerically.