Periodic Reporting for period 1 - S4I2T (Solar for Ice to Thrust)
Période du rapport: 2024-09-01 au 2025-08-31
Ice2Thrust.Space (S4I2T) is an EU-funded Pathfinder project (GA No 101161690) pioneering a new paradigm in sustainable space mobility. Its core ambition is to demonstrate a solar-electric water propulsion system and the enabling architecture for in-space resource utilisation (ISRU). By converting sunlight into thrust via water electrolysis, Ice2Thrust aims to prove that water – abundant, non-toxic, and easily storable – can serve as the cornerstone of a self-sustaining, circular space economy.
The project’s scientific and technological objectives are to develop and validate a Water Electrolysis Propulsion (WEP) system that surpasses the performance of conventional chemical propulsion while remaining green and storable; to demonstrate an end-to-end ISRU chain in which water is extracted from icy regolith and converted directly into thrust under vacuum conditions; to design autonomous guidance and docking technologies based on reinforcement-learning methods capable of enabling safe and intelligent spacecraft refuelling; and to formulate a holistic roadmap and commercialisation strategy that consolidates Europe’s leadership in in-orbit servicing, assembly and manufacturing.
Through these objectives, Ice2Thrust directly advances Europe’s capability for sustainable, non-Earth-dependent space operations, reducing reliance on toxic propellants such as hydrazine and expensive noble gases. The project’s expected impact lies in creating the scientific foundation and technology demonstrators for an economically viable, solar-powered mobility infrastructure extending from low-Earth orbit to lunar and deep-space destinations.
The project’s scientific and technological objectives are to develop and validate a Water Electrolysis Propulsion (WEP) system that surpasses the performance of conventional chemical propulsion while remaining green and storable; to demonstrate an end-to-end ISRU chain in which water is extracted from icy regolith and converted directly into thrust under vacuum conditions; to design autonomous guidance and docking technologies based on reinforcement-learning methods capable of enabling safe and intelligent spacecraft refuelling; and to formulate a holistic roadmap and commercialisation strategy that consolidates Europe’s leadership in in-orbit servicing, assembly and manufacturing.
Through these objectives, Ice2Thrust directly advances Europe’s capability for sustainable, non-Earth-dependent space operations, reducing reliance on toxic propellants such as hydrazine and expensive noble gases. The project’s expected impact lies in creating the scientific foundation and technology demonstrators for an economically viable, solar-powered mobility infrastructure extending from low-Earth orbit to lunar and deep-space destinations.
During the first reporting period (Month 1 to Month 12) the project advanced from conceptual design to tangible laboratory demonstration across all major domains. In-situ resource utilisation studies undertaken by TUM identified the Moon as the most suitable near-term candidate for extraterrestrial water extraction. A thermal-vacuum demonstrator using redirected sunlight to mine icy regolith has been designed, the necessary hardware procured, and subsystem integration is under way. The propulsion system development at TUM advanced on all major components: Prototypes of electrolyser, hot-gas thrusters and docking adapter were design, built and tested. Promising results could be achieved, yielding insights into the characteristics of hydrogen and oxygen production or the cooling efficiency of transpiration cooling for spacecraft thrusters. A coupled prototype of the propulsion system is being prepared for commissioning testing under vacuum conditions. At the University of Luxembourg, the work on autonomous docking and control defined the roles of chaser and target spacecraft within a reinforcement-learning framework. A modular simulation environment supporting both three- and six-degree-of-freedom tasks was established, enabling large-scale parallel training of control policies and their successful transfer from simulation to real-world testing in the Zero-G laboratory. EnduroSat meanwhile initiated the design of the spacecraft platform, developing the baseline architecture centred on a Remote Interface Unit (RIU) that governs the interaction between sensors, actuators and the Onboard Computer. These combined efforts have laid the technical groundwork for validating water-based propulsion, autonomous docking and in-orbit refilling under realistic laboratory conditions.
The Ice2Thrust project advances well beyond existing research by experimentally analysing the efficiency of lunar water extraction and recovery under varying conditions, supported by computational simulations. Its work goes beyond earlier feasibility studies by examining the composition of icy regolith and optimising the cold-trap process for ice retrieval, paving the way for future in-situ analyses on the Moon and a more mature extraction technology.
A space-capable PEM electrolyser could be systematically characterised for varying environmental conditions. Additionally, for the first time worldwide, additively manufactured porous metal structures were used for transpiration cooling of a rocket engine thrust chamber. The results show a strong potential for a significantly increase in fuel economy due to a decrease in amount of coolant needed. Furthermore, a docking adapter design could be investigated that is more compact and simplistic than currently available designs for the transfer of water between spacecraft.
At the same time, the project demonstrates the successful use of reinforcement learning for autonomous docking, achieving robust simulation-to-real transfer through large-scale training and validation in the Zero-G laboratory. Continued work on constrained and model-based reinforcement learning is expected to enhance safety, adaptability, and autonomy for future in-space servicing operations.
Finally, the development of a dedicated Remote Interface Unit for a satellite platform marks a technological breakthrough in managing the complex operations of a water electrolysis propulsion system. This architecture validates water as a safe, sustainable propellant and lays the groundwork for a new European ecosystem in in-orbit servicing, refuelling, and assembly, with future progress depending on hardware maturation, in-orbit demonstration, and the adoption of standardised interfaces to enable commercial interoperability.
A space-capable PEM electrolyser could be systematically characterised for varying environmental conditions. Additionally, for the first time worldwide, additively manufactured porous metal structures were used for transpiration cooling of a rocket engine thrust chamber. The results show a strong potential for a significantly increase in fuel economy due to a decrease in amount of coolant needed. Furthermore, a docking adapter design could be investigated that is more compact and simplistic than currently available designs for the transfer of water between spacecraft.
At the same time, the project demonstrates the successful use of reinforcement learning for autonomous docking, achieving robust simulation-to-real transfer through large-scale training and validation in the Zero-G laboratory. Continued work on constrained and model-based reinforcement learning is expected to enhance safety, adaptability, and autonomy for future in-space servicing operations.
Finally, the development of a dedicated Remote Interface Unit for a satellite platform marks a technological breakthrough in managing the complex operations of a water electrolysis propulsion system. This architecture validates water as a safe, sustainable propellant and lays the groundwork for a new European ecosystem in in-orbit servicing, refuelling, and assembly, with future progress depending on hardware maturation, in-orbit demonstration, and the adoption of standardised interfaces to enable commercial interoperability.