Autonomous Docking Manoeuvre Testing in the Framework of the ERMES Experiment

The rise of the “New Space Economy” has expanded access to low-Earth orbits for commercial, non-profit, and educational entities. This has driven significant growth in the small satellite market, offering a low-cost solution for various missions. Autonomous proximity operation systems for small satellites are actively studied for their wide-ranging applications. Experimental Rendezvous in Microgravity Environment Study (ERMES) is a student project, which aimed at testing an autonomous docking manoeuvre between two free-flying CubeSats mock-ups in a reduced gravity environment. The manoeuvre is characterized by an active Chaser and cooperative Target approach. In particular, the Chaser is equipped with a cold gas propulsive system based on expendable CO2 cartridges for three-dimensional manoeuvering, whereas the Target has a set of reaction wheels for attitude control. The magnetic post-manoeuvre connection is achieved thanks to a dedicated miniaturized docking interface. Moreover, the reduced gravity conditions have been achieved by participating in the European Space Agency (ESA) 79th Parabolic Flight Campaign thanks to the selection in the ESA Fly Your Thesis! Programme 2022 (FYT). This article provides an overview of the ERMES experiment, discussing its main objectives and key design solutions. It first describes the design of the Guidance Navigation and Control subsystems of the two mock-ups, then discusses the results of the parabolic flight campaign, and finally focuses on the analysis of a specific parabolic test, where the Chaser was able to dock by recovering a high overall misalignment.