ETHILE: A Thruster-In-The-Loop Facility to Enable Autonomous Guidance and Control of Autonomous Interplanetary CubeSat

As the number of interplanetary space missions keeps increasing thanks to the reduction of spacecraft development and integration costs, there is the urge of avoiding the saturation of the ground infrastructure required to operate satellites. The aim of the EXTREMA project, which has received fundings from the European Research Council, is to solve the aforementioned issue by enabling deep-space autonomous spacecraft. This work presents the EXTREMA Thruster in The Loop Experiment (ETHILE), a facility under development at the DART laboratory of the Politecnico di Milano. Its aim is to test and validate novel guidance algorithms tailored for satellites traveling autonomously in deep space. Therefore, it shall model the real actuation of low-thrust propulsion systems, measure the produced thrust, and feed the measurements to a high-fidelity numerical propagator. It is worth noting that a true real-time simulation would require an extremely long time: to complete an interplanetary transfers many months or even years are needed. EXTREMA aims at exploiting a scaled model of the physical system, and to correlate the results with the original one thereafter. Through a mapping between the original system and a fast-evolving one, it will be possible to execute the guidance and control simulations in a shorter time frame, which will last only a few hours or days. Once detailing the mapping principle, the paper describes the layout and characteristics of the ETHILE facility, followed by an overview of the guidance and control algorithms, developed in the framework of EXTREMA. Finally, some preliminary results are given and future developments are outlined.