Green SWaP

Advancing Space Propulsion for a Sustainable Future

Green SWaP - Green Solar-to-propellant Water Propulsion

Green SWaP is a revolutionary research project funded by the European Innovation Council (EIC) Pathfinder program. It aims to develop core technologies for a new class of in-space water propulsion, converting water directly into high-performance storable propellants using solar energy.

Water offers unparalleled handling and storage advantages both on Earth and in orbit. It guarantees safer, cheaper, faster and more reliable supply chain and operations, which are growing demands of the space sector. Through in-situ resource utilization on the Moon and other bodies, water can become a renewable source of propellant, enabling self-sufficient mission profiles. Moreover, water provides dual-use benefits in future human outposts by serving as a working fluid in life support systems and as radiation shielding fluid.

Conventional water propulsion is currently limited by the low density of gaseous propellants (oxygen and hydrogen) and by the extreme combustion temperatures. To achieve higher thrust levels, a new class of water propulsion systems is needed.

Green SWaP pioneers the direct onboard conversion of water into Hydrogen Peroxide and Hydrogen using solar energy. Unlike traditional electrolysis, this yields a propellant combination with superior storability and density, which burns at significantly lower temperatures.

The project targets a TRL increase for all critical subsystems:

Microgravity Conversion: An innovative system to convert water into in zero-g environments.
Refinement: Concentration of Hydrogen Peroxide to rocket-grade (High-Test Peroxide, HTP).
Storage: Safe storage of hydrogen in lightweight inflatable tanks.
Next-Gen Thrusters: The generated propellants feed two distinct propulsion units:

1 N Solar Thermal Thruster (STT): Uses hydrogen for precise attitude control maneuvers.
200 N Bipropellant Engine: Uses HTP and Hydrogen for high-thrust main propulsion.

The Space Propulsion Laboratory (SPL) at the University of Pisa serves as the Project Coordinator for the entire consortium. SPL is leading the development and testing of the 200 N-class bipropellant main engine prototypes, pushing the boundaries of green propulsion performance.