Yes, modular construction from individual items, additive manufacturing, in-situ printing and other approaches are all eligible. In all cases, the manufacturing of at least one representative unit (e.g. a brick, an individual building block item or a representative element of a continuous structure) must be conducted during the Phase 3 field test. The production and deployment of the structure may involve pre-manufactured units brought to the field test by the teams.

No, the physical demonstrations will focus on manufacturing the construction output and deploying the structure. Upstream steps should be identified and explained in the construction concept description and in the application scenario, including any feedstock preparation, size sorting, compaction or site preparation required for your idea. These steps may be completed manually or in advance where needed and do not have to be automated as part of the live demonstration. 

Yes, hybrid concepts are eligible. Teams must identify the imported materials, consumables and equipment required for their idea. Greater dependence on Earth-supplied materials or complex imported infrastructure will reduce the sustainability or infrastructure-complexity scores though.

“Structural” is used broadly to distinguish construction outputs assessed through their geometrical, mechanical and integrity-related criteria, unlike standalone products assessed for functional properties such as radiation or thermal shielding, which fall outside of the scope of the challenge. Horizontal and vertical infrastructure remains relevant where the proposed output has a credible use case and can be evaluated against suitable mechanical or geometrical requirements. The exact structural and mechanical criteria will be defined in the Phase 2 documentation. 

Yes, this is explicitly considered within the scope of the Challenge.

No, a technology does not need to have never been demonstrated before. Both new and established approaches may be competitive where the concept is credible and presents a strong application scenario as well as maturation pathway.

There is no fixed minimum level; teams should clearly present the validation already completed through the written submission and video. The proposed development work and use of the Phase 2 and final-prize funding also forms part of the evaluation.

Yes, but these are separated across the Challenge phases. Phase 2 focuses on manufacturing a representative construction unit at the team’s premises. Phase 3 requires teams to manufacture at least one unit at LUNA and then deploy or construct a structure. For continuous construction concepts, the team defines what constitutes a representative “unit” or section.

No, this is not required as robotic and tele-operated approaches are permitted, while direct human intervention in the construction area during the demonstration is not. Remote manual control from LUNA mission control is permitted.

Yes, the system may be manually loaded and prepared before the start of the demonstration. Manual reloading during the construction operation would constitute human intervention is not permitted and will affect scoring.

The live demonstration of manufacturing of a construction unit in Phase 2 and the field test demonstration of unit manufacturing and structure construction in Phase 3 must be demonstrated physically. Manual control of these activities is allowed, but must be performed remotely. Digital models can support the description and analysis of the wider value chain. Manual operations can be used to represent or support the upstream stages in the wider value chain (e.g. site preparation, initial feedstock loading…). However, manual operations are not permitted within the scope of the required live demonstrations. 

No explicit one-to-one scale requirement is set. A scaled demonstration is acceptable where it clearly demonstrates the construction process and relevant performance. Teams must explain how the technology scales to the proposed lunar application, including the implications for materials, energy, equipment and operations etc.

Yes, provided the approach is justified and the pre-manufactured units remain representative of the proposed concept in their relevant characteristics (such as mass, surface condition, deployment/assembly behaviour,…). At least one unit still has to be manufactured using the demonstrated process and feedstock during the field test. 

The evaluation will include structural properties, integrity and performance against relevant benchmarks. Because the proposed concepts may differ substantially, a single universal test (e.g. compressive or flexural testing) has not been prescribed. Teams may be asked to define benchmarks appropriate to their concept, against which performance will then be assessed. The specific tests, properties and scoring approach are being finalised and will be set out in the Phase 2 Call for Proposals. 

Not as part of the field demonstration and evaluation. The physical evaluation focuses on construction and mechanical performance. Teams must nevertheless explain in their application scenario why the concept is compatible with the lunar environment and how long-term conditions could affect their construction output.

The baseline for the application scenario should be based on a lunar South-polar location. EAC-1 regolith simulant is proposed to be made available by ESA to requesting teams, as it is available in practical quantities in the LUNA facility. Teams using EAC-1 should explain how their process transfers to South polar highland regolith and how sensitive it is to variations in regolith composition. 

No specific composition has been prescribed. Teams should support their selected composition with credible research or data and show how the process remains applicable to the location of their proposed lunar application scenario. 

Each team selected for Phase 2 will receive the same quantity of EAC-1 lunar regolith simulant. The exact quantity – expected to be 5 kg – will be confirmed in the Phase 2 Call for Proposals documentation. Teams will be asked to support the shipping arrangements by providing suitable packaging or containers. 

This allocation is intended to familiarise teams with the simulant used at ESA’s LUNA facility and to support compatibility testing. It is not intended to cover the full feedstock requirement for a team’s live demonstration. Teams may request from ESA additional quantities of EAC-1, subject to availability, for which the requesting team must cover the associated container and shipping costs. 

Imported binders and other Earth-supplied materials are permitted, but the proportion required for construction will affect the sustainability score. A concept requiring a high fraction of imported binder is expected to score less favourably than one which uses a smaller fraction, or which uses mainly materials that can be sourced locally. A description of materials considered locally available is available in Annex D of the OSIP campaign page. 

Materials which are depleted during the construction process and must be replenished for each construction operation are treated as consumables. This includes consumables used in the construction feedstock (e.g. binders,…), as well as consumables used for operating the construction equipment (e.g. cooling fluids, cutting tools…). A material that is retrieved at the end of a manufacturing operation and reused for the next ones (e.g. recovered process water), may no longer be treated as a consumable if the recovery is convincingly explained and demonstrated. The amount of consumables used for the proposed in-situ construction concept will affect the sustainability criterion in the evaluation.  

If water is used as part of the proposed in-situ construction process, the team may demonstrate recovery, for it not to be considered as a consumable. The team should explain the recovery approach as part of the Phase 1 proposal. The team should then demonstrate and quantify the recovery during the Phase 2 unit-manufacturing live demonstration at their premises. During the LUNA field test, a qualitative demonstration of recovery can be considered sufficient, provided that quantitative demonstration of recovery has been witnessed by ESA and evaluated at Phase 2.

Yes, the evaluation is expected to consider how realistically the required feedstock could become available in a lunar infrastructure scenario. Concepts using minimally processed locally available feedstock (e.g. regolith) may be more readily deployable than concepts dependent on a refinement of metallic regolith constituents or on the extraction of large quantities of water. The equipment, resources (energy, consumables) and extraction time required in the feedstock-preparation chain, for the quantities relevant to the proposed in-situ construction concept, must be explained in the Phase 1 proposal. The equipment and resources needed for the live demonstration and field demonstration must also be described in the Phase 2 and Phase 3 proposal, respectively. They will be assessed as part of an infrastructure complexity criterion in the evaluation.  

No fixed requirement is set for the quantity of water applicable to the application scenario, and teams may propose water-based processes. However, the water quantity required for their proposed in-situ construction concept and the likelihood of availability in the needed quantity, at the relevant stages of the scenario, should be described and duly justified in the application scenario. For instance, dependence on the availability of large quantities of water, in a scenario corresponding to the early stages of a lunar-base build-up, may adversely affect the scoring for evaluation criteria related to sustainability and credibility. 

No preference exists for one innovation category over another. Concepts will be judged on the credibility of the process, if the unit and structure construction outputs meet the applicable criteria, and if the overall concept performs well against sustainability, scalability, clarity of the maturation pathway and value proposition for lunar infrastructure implementation. 

Use of locally available materials and minimisation of imported consumables will form part of the sustainability evaluation. The evaluation criteria weighting factors for Phase 1 are indicated in Annex B on the OSIP campaign page. The finalised criteria, scoring methods and weighting factors for Phase 2 and Phase 3 will be published in the Cover Letter for each Restricted Calls for Proposals.  

Vacuum operation is not to be demonstrated during the baseline field test, but lunar-environment compatibility shall be addressed in the application scenario. A process that performs well at LUNA but cannot operate in a vacuum would be reviewed more negatively. In the case where a team proposes a process that requires vacuum to be implemented and cannot be demonstrated in a field test at ambient pressure, adequate explanations should be included in the Phase 1 proposal, for ESA’s consideration on potential accommodations to the demonstrations’ settings. 

Such requirements should be clearly indicated and justified in the proposal, for ESA’s consideration on potential provision of inert gas or gas chamber.   

Natural sunlight is not available inside LUNA. The facility has a sunlight simulator, but it is not expected to provide the energy needed for thermal processing. Use of the nearby DLR solar furnace is dependent on availability, logistics and potential cost constraints. Requirements for use of this facility should be clearly indicated and justified in the proposal, for ESA’s consideration. 

Yes, teams may bring the supporting hardware needed for their process. Its energy demand, mass, volume and complexity must be declared and will form part of the evaluation.

There is a standard physical limit imposed by the LUNA electrical infrastructure. Teams must state the peak and baseline power requirements of their systems. Energy consumption is also an evaluation consideration, and lower energy demand per construction output is advantageous.

Likely not, and its use cannot be guaranteed. Teams should not design their concept on the assumption that gravity offloading will be available.

No formal hard limit has been set. Teams were advised to use the payload capability of a currently envisaged lunar lander, such as Argonaut, as a realistic reference. Larger, heavier or more complex infrastructure is less favourable in the evaluation.

No; launch-vehicle availability and the logistics of a future lunar mission are outside the scope of the Challenge. These aspects should not be the focus in the in-situ concept description. However, teams are requested to describe how the proposed concept would be matured and used in a lunar surface infrastructure, as part of the application scenario.  

An entity without registration in an eligible country may submit to Phase 1, but it must have an eligible registered entity in place when submitting for the Phase 2 proposal. Otherwise, it cannot proceed to Phase 2 or receive a cooperative agreement.

Yes, an individual or informal team may submit at Phase 1. If selected for Phase 2, the team must identify or establish a legal entity in an eligible country that can register on ESA STAR, a requirement to submit the Phase 2 proposal and sign a cooperative agreement.

Yes, teams may combine individuals with different backgrounds and employment situations. The submission should describe the team and include short CVs. A lead legal entity will still be required for the cooperative agreement in later phases.

No hard profile requirement is set. Relevant experience, understanding of the lunar environment and ability to manage the proposed project will be considered in the evaluation. The lead must ultimately represent the entity able to enter into the cooperative agreement.

Yes, consortia involving multiple research entities or other eligible organisations are permitted.

Yes, provided there is no conflict of interest. An organisation may lead one submission and act as a partner or subcontractor in another.

Yes, where an entity has two distinct technology stacks or concepts, separate proposals are recommended so that each can be evaluated clearly.

They may participate in roles such as advisers, customers or other contributors without receiving Challenge funding which should be clearly described in the idea submission. Transferring funding to a participant outside the eligible countries would require special approval by ESA’s contracts team on a case-by-case basis, and only in exceptional circumstances.

No, this OSIP campaign is specifically the pathway to the Challenge field test. A concept seeking support through another OSIP route would need to be submitted separately to an appropriate open call.

The Challenge is intended to identify promising solutions in a field where no preferred technology, nor a mature market is yet established. Unlike a conventional tender with tightly prescribed specifications, it allows ESA and ESRIC to scout a broad range of concepts and support the strongest towards potential future in-situ demonstration, commercialisation and implementation in a lunar context. 

Universities, start-ups, established companies, consortia and individuals with a credible lunar construction concept are all potential participants, subject to the eligibility and contracting requirements.

Questions can be submitted through the OSIP platform until the call closes. Participants are encouraged to ask questions early enough, to be able to use the response in their submission. A further live Q and A opportunity will be the 2nd webinar, on the 15 September 2026.