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In-Space Green Propulsion Innovations in the EIC Portfolio �on In-Space Solar Energy Harvesting for Innovative Space Applications

NaFSKI-VI: Session: “Game-changers” for in-space solar energy harvesting

T. Mrazek, L. Blondel, G. Sanchez-Arriaga

28.10.2025

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WP2023:ISSEH - WG3

Goal: advancing research, technology, and applications related to in-space green propulsion

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Common Research Areas

Catalytic ignition and decomposition 

Advanced Cooling Technologies for Thrust Chambers 

Ultra-compact deployment systems for large flexible surfaces�Required to deploy tether tapes or solar panels. 

Inflatable and deployable tanks �Required to store gaseous propellants once produced in orbit 

Production and concentration of propellants in orbit from stored water �Using photo-electric catalysis and/or plasma-based synthesis and/or electrolysis 

Solar thermal propulsion �With focus on the thruster and of the energy storage/heat transfer components 

Close-Proximity, docking and propellant (water) refilling technologies�Including ACS, control algorithms, docking adapter and fluidic systems 

CubeSat propulsion system integration�For validation of propulsion technologies

ISRU: Water extraction from icy regoliths�Including investigating purity aspects for subsequent usage for propellant production in water-based propulsion systems

DC/DC-Converters �Required to distribute power from solar panels to consumers (e.g. electrolyser) 

Ice2Thrust.Space (S4I2T) is an EU-funded project [GA number 101161690]

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The Ice2Thrust Project

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Project Management

Water Electrolysis Propulsion

Water Extraction

ISRU end-to-end Demo

Autonomous Docking & Proximity Operations

HIL Docking & Propellant Refilling Demo

CubeSat Integrator

Platform Provider

Market Perspective

Commercialisation & Dissemination

Ice2Thrust.Space (S4I2T) is an EU-funded project [GA number 101161690]

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Ice2Thrust Architecture

Single propellant and solar energy provides all mobility needs

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H2O is extracted

Moon / NEO

self-sustainable �H2O Distribution

    • Cold-gas thrusters (attitude control)
    • Hot-gas thruster (high-thrust maneuvers)
    • Electric thruster (high Δv maneuvers)

Ice2Thrust.Space (S4I2T) is an EU-funded project [GA number 101161690]

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Ice2Thrust Architecture

Single propellant and solar energy provides all mobility needs

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H2O is extracted

Moon / NEO

self-sustainable �H2O Distribution

Autonomous Docking

    • Robust control through model-based RL
    • Enables in-space manufacturing, assembly and robotics

Propellant Refilling

    • Utilising simplicity of water as propellant
    • Lifetime of a satellite is no longer predefined
    • Water is accessible in space

Ice2Thrust.Space (S4I2T) is an EU-funded project [GA number 101161690]

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Ice2Thrust Architecture

Single propellant and solar energy provides all mobility needs

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H2O is extracted

Moon / NEO

self-sustainable �H2O Distribution

In-Space Water Extraction and Utilisation

    • Potential for first economically viable use of in-space resources
    • Eliminate need for constant replenishment from Earth

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Ice2Thrust.Space (S4I2T) is an EU-funded project [GA number 101161690]

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Electrolyser

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  • First prototype designed, built, and tested
  • Accumulated >450h of operation

Hot-gas Thruster

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  • 1st battleship testbed
  • 2nd manufacturing proof-of-concept of technology
  • 3rd prototype a vacuum integrated thruster

Cold-gas Thrusters

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  • Single thruster prototype testing early 2026
  • Parallel conceptual design of attitude control array

Refilling Interface

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  • FDI V1 in testing
  • V2 conceptual design ongoing in parallel

Ice2Thrust.Space (S4I2T) is an EU-funded project [GA number 101161690]

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Electrolyser

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  • First prototype designed, built, and tested
  • Accumulated >450h of operation

Hot-gas Thruster

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  • 1st battleship testbed
  • 2nd manufacturing proof-of-concept of technology
  • 3rd prototype a vacuum integrated thruster

Cold-gas Thrusters

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  • Single thruster prototype testing early 2026
  • Parallel conceptual design of attitude control array

Refilling Interface

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  • FDI V1 in testing
  • V2 conceptual design ongoing in parallel

Vacuum Facility

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  • Procurement ongoing
  • Assembly Q4 2025
  • First test by the end of the year

Ice2Thrust.Space (S4I2T) is an EU-funded project [GA number 101161690]

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Green Solar-to-Propellant Water Propulsion�Overview of the EIC Green SWaP Project

NAFSKI Conference

28th October 2025

Project funded by

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Green SWaP’s Consortium

Overview of the Green SWaP Project – NAFSKI Conference

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6 Partner Organizations across 5 countries

Coordination by the University of Pisa

HORIZON-EIC-2023-PATHFINDERCHALLENGES-01-05

EIC Pathfinder Challenge: In-space solar energy harvesting for innovative space applications

Grant Agreement 101161583

Pathfinder (TRL 1-4)

Transition (TRL 4-6)

Accelerator (TRL 6-9)

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Green SWaP Reference Mission Use Case

The Green SWaP system consists of two modules:

  • A reusable orbital stage, performing in-orbit services, refueled in Sun-Synchronous orbit
  • A water-based in-orbit propellant production & concentration station in SSO, powered by solar energy

Overview of the Green SWaP Project – NAFSKI Conference

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Green SWaP’s Architecture & Technologies

Overview of the Green SWaP Project – NAFSKI Conference

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Green SWaP’s propulsion system architecture:

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Goals – In-space Solar Fuel Production

Overview of the Green SWaP Project – NAFSKI Conference

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  1. Develop and test 3 different methods of converting water into H2O2 & H2
  2. Develop and test an H2O2 concentrator system able to work in space environment
  3. Develop and test an inflatable storage tank for H2

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Goals – In-space Green Propulsion

Overview of the Green SWaP Project – NAFSKI Conference

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  1. Develop and test a 1N-class solar thermal thruster to be operated with hydrogen propellant
  2. Develop and test a 200N-class bipropellant thruster to be operated with H2 and H2O2 propellants

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Technological Innovations of the Green SWaP Project

  • Objective of the Pathfinder phase: Reach TRL 4 by 2028 for all subsystems
  • Next step: Naturally continue the innovation to mature the technologies to higher TRLs in subsequent phases

Overview of the Green SWaP Project – NAFSKI Conference

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State of the Art

Green SWaP Innovations

No coproduction of H2O2 and H2 for space applications

In-space production of H2O2 and H2 from water through different approaches:

  • Photocatalytic
  • Electrocatalytic
  • Plasma-based

No H2O2 concentrator for space applications

H2O2 concentrator for in-space environment utilization

A few bimodal toxic propulsion systems used in space

Development of integrated bimodal propulsion systems

Solar Thermal Propulsion only theoretically studied

Development of a solar thermal propulsion concept

Toxic liquid bipropellant systems used in space

Development of a chemical propulsion system based on H2O2 and gaseous H2

Water & Sunlight

Greener Propellants Production

Use for OTVs In-space Propulsion

In-orbit Services

In-Situ Resource Utilization �(water refill)

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System Requirements Review (SRR)

Overview of the Green SWaP Project – NAFSKI Conference

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  • System-Level alignment between Propellant Supply & Propulsion Demand
  • 10th April 2025

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Green SWaP’s Project Status (end of the 1st year)

Preparation & initial validation of photocatalytic, photo-electrocatalytic and plasma-based approaches for H2 and H2O2 coproduction

  • material selection, reactor design and setup of experimental infrastructures

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Achievement of the 2nd milestone: Preliminary Design of Thruster Prototypes (PDR) - 10th October 2025

  • Frozen requirements, design trade-offs (challenges & solutions), risks & mitigations, CAD

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Overview of Chemistry & Propulsion Activities since SRR

  • D2.1: Green SWaP Requirement & Test Plan

Overview of the Green SWaP Project – NAFSKI Conference

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E.T.COMPACT �Compact and propellant-less Electrodynamic Tether system based on in-space solar energy

Presentation prepared by the E.T.COMPACT Team

Annual Portfolio Meeting, October 27th, 2025.

Sofia, Bulgaria.

EIC Pathfinder Project funded by the European Innovation Council (101161603)

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The E.T.COMPACT Project

  • In-space propellant-less propulsion

Bare electrodynamic tethers are long in-orbit conductors that exchange momentum with a planet magnetosphere to produce a force without using propellant.

The tether captures electrons from the ambient plasma. An electron emitter close the electric circuit to reach a steady current

  • In-space propellant-less propulsion + power harvesting

Bare-photovoltaic tethers are a subclass of electrodynamic tether with thin film solar cells printed on one side to provide propellant-less propulsion and sun energy.

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The E.T.COMPACT Project

  • Title and Acronym: Compact and Propellant-less Electrodynamic Tether System Based on In-Space Solar Energy (E.T.COMPACT)
  • Partners:

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  • Objectives:
  • Reach TRL 4 for a very compact (3U and 5 kg) and non-autonomous Green Mobility Module based on a spinning electrodynamic tether.
  • Prepare a prototype of a bare-photovoltaic tether based on 2T CIGS/PVK solar cells

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The E.T.COMPACT Project

Avionics

Software

Electron Emitter

Green Mobility Module inside a 6U and 3D printed Platform

Deployment Mechanism

Bare-Photovoltaic Tether

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Project status

  • Modelling and Simulation: optimal spin plane and performance determined & software developed.
  • GMM System Engineering and platform: requirements and preliminary design are finished and mass & power budgets ready.
  • Deployment Mechanism: requirements prepared, trade off analysis carried out, deployment and spin-up strategies studied, and preliminary design finished.
  • Electron emitter: 5 expellant-less cathodes, including thermionic and field emission, were studies numerically and experimentally.
  • Avionics: requirements prepared, ADCS architecture designed, component trade-off & selection made.
  • Bare-Photovoltaic Tether: requirements and model prepared, CIGS and PVK cells engineered (band gap, additives and processes, etc), back contacting system completed and laser integration into cutting and stacking machine.

Workplan is developing as expected.

Important challenges are expected in the second year

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Multi-Project In-Orbit-Demonstration

  • Most of the Space Portfolio project’s innovations target to TRL 4 by 2027.
  • Natural continuation is to mature innovations from 2027-2029 and make an IOD of selected technologies
  • As part of the Portfolio Strategic Plan, we collected key data of the innovations (mass, volume, power).

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  • In the next two years we plan to conduct basic system engineering activities with two objectives:
  • Promote a future IOD.
  • Identify synergies and foster project collaborations to maximize impact.

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Thank you for your attention!

Contact us for more information:

tomas.mrazek@tum.de (Ice2Thrust)

angelo.pasini@unipi.it (Green SWaP)

gonsanch@ing.uc3m.es (E.T. Compact)

Interested in working with us?