Harnessing Solar Energy to Transform Water into Green Rocket Propellant

Overview

Green SWaP (Green Solar-to-Propellant Water Propulsion) is a groundbreaking project that uses solar energy to convert water into environmentally-friendly propellants: hydrogen peroxide H2O2 and hydrogen H2.

Inspired by the way plants convert sunlight into energy by photosynthesis, this project will integrate advanced technologies to step toward establishing a sustainable method for producing propellants directly in space, enabling low-cost, eco-friendly, and self-sufficient future space missions, facilitating safer and more efficient in-orbit services. 
Green SWaP indeed aims to overcome the challenges of producing and storing liquid propellants in space by developing advanced chemical processes, in particular three solar-based methods, to convert water into H2O2 and H2. These processes are also currently studied for terrestrial application.  

Key objectives

Green SWaP System Requirements

  • Define requirements for the Green SWaP bimodal propulsion system and its components
  • Establish a qualification roadmap based on TRL 4 technology testing outcomes

In-Space Solar Energy Harvesting

  • Develop a solar-powered module for H₂O₂/H₂ production using photo/electrochemical or plasma synthesis
  • Test a high-grade High-Test Peroxide (HTP) concentrator
  • Explore innovative inflatable tank solutions for hydrogen gas storage

H₂O₂ and H₂ for In-Space Propulsion

  • Develop and test a 200N-class chemical thruster and a 1N-class solar thermal thruster using hydrogen-based propellants

Expected breakthrough

  • Development of photocatalytic and plasma-based approaches for production of H2O2 and H2 from water
  • Creation of a high-efficiency H₂O₂ concentrator suitable for in-space operations.
  • Development of a novel chemical bimodal propulsion system that uniquely integrates H₂O₂ and gaseous H₂, a combination never attempted before.
    Implementation of a solar thermal propulsion with innovative concept
  • Design of an inflatable tank for H2 storage compatible with the space environment

Benefits

Green and sustainable and in-space propulsion from water and solar energy

Elimination of toxic and hazardous in-space propellants 

Easier and safer space mission and in-orbit services 

Potential for in-situ water refuelling to extend spacecraft missions 

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Consortium

The Green SWaP initiative is driven by a consortium of leading European universities, research institutions, and industry partners. Together, they bring cross-sectoral expertise to innovate, test, and validate green propulsion technologies.