How to address EU strategic autonomy in space technology proposals (HORIZON-CL4-2025-02-SPACE-72)
13th June 2025 at 3:52 pm
With the deadline for the HORIZON-CL4-2025-02-SPACE-72 call topic fast approaching on 25 September 2025, now is the time to prepare compelling proposals that will advance European non-dependence in critical space equipment. This call topic, part of Horizon Europe’s Cluster 4 “Digital, Industry and Space” Work Programme, calls for research and innovation actions (RIAs) targeting two strategic technology areas: chip-scale atomic clocks and solar cells. In this blog post, we explain how proposals can best respond to the EU’s goals for open strategic autonomy in the space sector and what elements evaluators most likely expect to see.
The EU’s ambition – open strategic autonomy in space
The HORIZON-CL4-2025-02-SPACE-72 topic is rooted in the broader EU ambition to reduce dependency on non-European technologies in critical domains, in line with the European Economic Security Strategy and the European Space Strategy for Security and Defence.
Focus areas – chip-scale atomic clocks and solar cells
According to the call text, proposals must address only one of the following two technology domains, both vital to secure EU capabilities in satellite navigation, Earth observation, and telecommunications:
1. Chip-scale atomic clocks (CSACs) underpin precise timing in global navigation systems, secure communications, and space-based science missions. The EU seeks innovation in miniaturised, energy-efficient CSACs that:
- Deliver improved frequency stability and environmental robustness.
- Are compatible with space constraints and radiation environments.
- Use components that are not subject to export control restrictions.
2. Solar cells: Proposals should advance European non-dependence in space-grade photovoltaic technologies, including:
- Multi-junction solar cells with high specific power.
- Use of non-toxic materials and low-cost production methods.
- Manufacturing processes that are scalable in Europe.
- Qualification for low-Earth orbit (LEO) or deep space missions.
Both topics require collaboration with end-users (e.g. ESA, EUSPA and satellite integrators) and a clear path to industrialisation.
Key aspects to obtain a competitive proposal
To align closely with the expectations for HORIZON-CL4-2025-02-SPACE-72, your proposal should:
Demonstrate technology readiness and scalability
Proposals should aim to reach technology readiness levels of TRL 5-6 for the solar cells and TRL 6 for the chip-scale atomic clocks by the end of the project and include:
- Functional prototypes tested in relevant space conditions.
- Pathways to space qualification and standardisation. Include a list of proposed applicable standards (e.g. ECSS, ESCC and MIL JEDEC) that are considered relevant.
- Engagement with European certification bodies, where applicable.
Build strong EU value chains and demonstrate non-dependence
Consortia should include European suppliers of raw materials and components, SMEs and research institutes specialised in advanced manufacturing and end-users and potential buyers of the resulting technology. Additionally, proposals must show how the project reduces dependency on non-EU suppliers. To this end, proposals must include a description of:
- The technology and high-level breakdown of the space equipment supply chain to be used. It needs to be demonstrated that the final product, as well as the supply chain, are free from any legal export restrictions or limitations, such as those established in the International Traffic in Arms Regulations (ITAR) or equivalent instruments applicable in other non-EU jurisdictions.
- Whether any part of the supply chain is affected by non-EU export controls, such as the Export Administration Regulation (EAR).
- The technology development process that the consortium intends to use for avoiding restrictions of non-EU states and assessing vulnerabilities of the supply chain.
In addition, as part of the work plan, the proposals must include specific tasks and associated confidential deliverables to be provided within the first 6 months of the project with the objective of:
- Analysing and describing, in detail, the full supply chain, each entity and its role in the supply chain, level of criticality and, if relevant, identifying dependencies from outside the EU.
- Describe the industrial technical roadmap and a business plan for commercialisation with an accurate understanding of applications needs, space mission insertion, including time to market indication, of the developed product.
- Reporting the list of relevant non-EU export controls with extra-territorial applicability for the specific technology/product under development, independently from the supply chain established for the EU-COM project.
- Undertaking a comprehensive literature review of the relevant technology/product, reporting the state-of-the-art and highlighting potential gaps between current EU solutions and competition from outside the EU.
Plan for dual-use potential
Where relevant, consider the dual-use applications of the technologies (civil and defence), especially for navigation and timing. This can strengthen the case for long-term sustainability and policy relevance.
Impact, exploitation, and EU alignment
The call topic explicitly requires that proposals address the EU’s Space Industrial Strategy and Strategic Compass objectives, include a clear exploitation plan with credible business models, detail how results will be taken up by ESA programmes or Copernicus/Galileo infrastructure and comply with EU export control and security rules.
Whether advancing ultra-precise timekeeping with chip-scale atomic clocks or ensuring solar power sovereignty in orbit, the HORIZON-CL4-2025-02-SPACE-72 call topic is a high-stakes opportunity to reinforce Europe’s independence in the space domain. With the September deadline fast approaching, consortia must move quickly to align with the technical, political, and industrial priorities that underpin this strategically vital call.
How accelopment can support
We assist researchers, companies and institutions by reviewing proposals or offering full writing support. Our multi-disciplinary and highly qualified team has many years of experience notably in projects in Energy, Materials, ICT and manufacturing and other areas. For example, we have successfully supported the PEPPERONI (perovskite/silicon tandem photovoltaics), SOLARX (concentrated solar power), CHEOPS (perovskite photovoltaics), macQsimal (quantum technology including atomic clocks), SOSLeM (fuel cells) and Mat4Rail (materials) projects. We look forward to discussing your project idea and how we can support you best!
Dr. Johannes Ripperger
Research & Innovation Manager
Andreia Cruz
Research & Innovation Project Manager