First Hotfire Tests Mark Major Milestone in Ice2Thrust’s Water Electrolysis Propulsion Thruster Development

On the picture: Exhaust plume while hotfire testing of the WEP transpiration-cooling pathfinder thruster at Technical University of Munich (TUM)

May 2025 — The Ice2Thrust project has successfully concluded the first phase of its Pathfinder thruster test campaign, marking a significant achievement in the development of sustainable in-space propulsion. These initial hotfire trials are a major step forward in validating the Water Electrolysis Propulsion (WEP) concept, which uses water as a renewable, space-storable fuel source.

One of the central technical challenges in harnessing hydrogen-oxygen combustion is managing extreme temperatures, which can reach up to 3500°C. To overcome this, the Ice2Thrust team is testing transpiration cooling—an advanced method where coolant gas is pushed through a porous combustion chamber wall, cooling it from within. After a reference series of uncooled tests, the team successfully achieved a cumulative burn time exceeding three minutes in the transpiration-cooled configuration.

In addition to combustion performance, the campaign successfully commissioned a catalytic ignition system, capable of reliable re-ignition—a key requirement for propulsion systems designed for multiple restart cycles in orbit. After careful optimization, the system demonstrated stable and repeatable behavior, with further improvements planned.

With these critical milestones achieved, Ice2Thrust is now preparing for the next stage: testing a vacuum-optimized thruster prototype, slated for late 2025. The continued development of WEP technology aims to enable efficient, reusable, and eco-friendly propulsion systems that support future space missions.

Contact: Sascha Dengler, Project Manager WEP Thruster (TUM), sascha.dengler(@)tum.de