Optimization of an electromagnetic soft-docking system for small satellites

Small satellites, and especially CubeSats (standardized satellites of modular nature), are currently widely used in the space industry, thanks to their low cost, fast development time and the possibility to exploit commercial off-the-shelf components. On orbit servicing, on orbit assembly and active debris removal are applications of great interest at the moment, and all these procedures involve the use of docking systems, which are a critical part of the space mission, especially for the small dimensions of the involved satellites. The docking action often comprehends a soft-docking procedure, which aims to perform a non-rigid contact between the two vehicles, and a hard-docking procedure, which instead establishes a rigid connection. SROC (Space Rider Observer Cube) will be a future mission of the European Space Agency. The main objective of the satellite is to perform proximity operations and docking with the larger vehicle Space Rider, a space laboratory that enables various payloads to operate in orbit. SROC is a 12U CubeSat that will be deployed from Space Rider cargo bay, will perform close observations and finally will dock back with Space Rider, by means of a dedicated smart docking system named DOCKS. This thesis focuses on the soft-docking subsystem of SROC, which comprehends an electromagnet and a damping system. Given a series of requirements, the electromagnet design has been optimized, and two different configurations have gone into production. The main goal is to keep a non-rigid contact between the two docking interfaces of SROC and Space Rider until hard-docking is completed. The damping system has been preliminarily analyzed by means of dynamic impact simulations. To conclude, an experimental set-up to find the electromagnetic force as a function of the air gap has been developed, and a commercial electromagnet has been tested in order to validate the set-up.