The S4I2T project seeks to develop a cost-effective and environmentally friendly solar electric water propulsion system. It aims to use water as a propellant to enable autonomous spacecraft docking and propellant refilling, promoting economic and environmental sustainability and facilitating in-orbit servicing, robotics, and in-space manufacturing. Furthermore, the project explores in-space water extraction and utilization from celestial bodies, contributing to a self-sustaining circular space economy based on solar energy harvesting.

The three technological elements at the project's core are:

1. Solar-Electric Water Electrolysis Propulsion: Water is used as a propellant and decomposed into gaseous oxygen and hydrogen, outperforming traditional chemical propulsion systems. Water's non-toxicity, versatility, and availability make it a cost-effective choice. It also utilizes solar energy for propulsion.
2. Autonomous Proximity/Docking Operations and Propellant Refilling: Water simplifies in-orbit refueling, reducing launch mass and extending satellite lifetimes. This supports in-orbit servicing and assembly, enhancing the impact of solar energy harvesting.
3. In-Space Water Extraction and Utilization: Water extraction from celestial bodies combined with the other technologies creates a self-sustainable space mobility infrastructure, offering long-term, Earth-independent operation.

The project aims to achieve several breakthroughs in developing a novel solar-powered propulsion system, addressing technological challenges and bottlenecks. It includes the development and lab demonstration of innovative components for a Solar Electric Water Electrolysis Propulsion System, autonomous proximity/docking algorithms, and end-to-end In-Space Resource Utilization (ISRU) validation.

Ultimately, the S4I2T project strives to position Europe as a leader in solar-energy-powered space mobility, fostering a sustainable and self-sustaining space economy.