Briefing meeting in advance of next Call for Medium and Fast missions
and of an exploratory call for mini-F proposals
in the ESA Science Programme

Questions and Answers

Topics: International collaborations, M missions, F and mini-F missions, General

On International collaborations

Q1: Regarding the collaboration on international/non-ESA flagship missions: how can the community propose mission contributions for that? Will there be a continuous open call for the community to apply when opportunities arise?

A1: The long-term implementation plan for the Science Programme includes a dedicated budget line for ESA participation in missions led by our international partners. This requires iteration with the partners to set the boundaries and conditions for participation. The community will be informed about this, allowing time to reflect on possibilities. As an example, the community in Europe has expressed enthusiasm for NASA's future flagship missions and ESA is maintaining a dialogue with NASA about these missions. The plans and the budget that can be dedicated to this will depend on the resources allocated at the ESA Council Meeting at Ministerial Level in November 2025. A Town Hall meeting will be organised in early 2025 to engage the community interested in NASA's Habitable Worlds Observatory (the first of the NASA flagship missions to move forward) and discussions will continue with Member States.

Q2: The contribution of ESA to JWST was at the level of an M mission. Did ESA consider contributing to the next NASA Flagship mission, i.e. Habitable Worlds Observatory? If so, what would be the framework for such a contribution? Many scientists are very interested by the science with HWO. Do you confirm that M8 is not the framework for this contribution? What about F3 or F4?

A2: The forthcoming M and F Calls are dedicated to ESA-led missions and are therefore not the framework for a contribution to the NASA Flagship missions. In the event of a successful outcome to the Ministerial Meeting in 2025 there will be a dedicated budget line dedicated to participating in these NASA missions, of which the Habitable Worlds Observatory (HWO) would be the first flagship mission under discussion. A Town Hall meeting will be organised in early 2025 for a discussion with the community to assess interest in participation in HWO.

Q3: It has been made clear that the F- and M-class missions must be ESA-led. Does it mean that the only possibility to contribute an Entry Probe to the future NASA Uranus Orbiter Probe mission is through requesting extra funding to the Member States at the next Ministerial Meeting? Will there be an official request? Are there other alternatives?

A3: The Science Programme has a number of budget lines attributed to various activities, one of which is associated with international cooperation, in particular, for contributions to the NASA flagship missions (as well as for Missions of Opportunity, which are contributions of maximum 50 million euro to missions led by international partners). Once the level of resources has been defined by the Ministerial Meeting in 2025, the Science Programme Committee will be consulted on how best to accommodate the ambitions of the Member States' science community with the available resources.

Q4: Is there any limit on the amount of non-Member States (international) contributions? Like the 1/3 maximum external contributions for NASA missions?

A4: There is no fixed number, but rather it is a matter of responsibility. It is important that the critical mission elements are under ESA control and this clearly implies a limit to what a partner can contribute. Contributions from international partners are discussed on a case-by-case basis and take into account, for example, also the technology readiness level of an item proposed by a partner. One can also think about this from the perspective of risk. Often, when a mission starts Phase A, the partner is not yet in a position to commit and this can be a non-negligible risk if the partner's contribution is large or mission-enabling. One way to mitigate this risk is to have a fall-back scenario which is purely European as mentioned in ESA's presentation (see e.g., slide 9), possibly with acceptable science descoping options.

Q5: Can associate Member States, like Latvia, take part in ESA mission proposals as a consortium partner?

A5: The process is open to contributions from international stakeholders and ESA welcomes contributions from European non-Member States as part of a consortium proposing a mission.

Q6: Concerning M-missions and, if NASA is considered as partner, what is needed from them as letters of endorsements (firm commitment?) and at which stage?

A6: For the Phase-1 proposals, no letters of support are required from potential partners, including Member States. For proposals that subsequently proceed to Phase-2, it is standard practice to ask for letters of support from Member States and international partners. Although at this phase it is still too early for firm commitments, there will be a careful evaluation of the partners' commitment to follow the work through the study and as the final selection phase approaches there will be a re-assessment of the level of support to the payload, from international partners and from Member States.

Q7: Can non-European launch vehicles such as Falcon 9 be considered for mini-F missions to reduce cost? And would foreign contribution (for instance US) for launcher be considered? Also, does the mini-F cost cap of 50 million euro include the launch cost?

A7: The mini-F budget is a Cost at Completion (CaC) to ESA (as for the M or F cases) therefore encompassing all ESA costs, including launch costs as applicable. However, please note that the mini-F Call is an exploratory call for ideas and the associated ESA CaC is indicative at this stage. Furthermore, the launcher cost is not expected to be a dominant fraction of the CaC (typically <10%), so the detailed assumptions on the launcher will have little impact on the assessment of mini-F missions' potential. The mini-F proposals should focus on the scientific merit of the intended mission and on its feasibility within the programmatic boundaries (cost and schedule). A fixed allocation (<10%) will be recommended by ESA for the launcher in the mini-F Call for focussing the proposal effort.

Regarding the use of commercial US launchers, ESA's policy is to privilege the use of European launchers when the launch is funded by ESA. The launcher market is evolving rapidly and there are small launchers in development in Europe, some of which may be available before too long. A ballpark figure for such launches could be of order 15 million euros, and these launchers could be capable of launching 100s of kilograms into orbit, which would mean that there could be multiple passengers, and the individual launch cost of a mini-F would be in the expected range.

On M missions

Q8: Can the current M7 Phase A candidates submit to M8? If not, can the science theme be submitted to M8 (given that the M7 selection will not be completed before the end of the M8 Phase-1 process)?

A8: The community is free to propose any science theme and the themes addressed by the current M7 candidate missions (M-MATISSE, Plasma Observatory, THESEUS) are not excluded from the upcoming calls, neither are any of the M7 proposing teams precluded from participating in proposals. It would, however, not make sense to propose one of the candidate M7 missions for the M8 opportunity, because at this stage, all three teams should be making the utmost effort to win the M7 launch opportunity. For the two unsuccessful M7 missions, there will be the possibility to submit for the M9 opportunity in 2-3 years' time, with the intervening time used to reflect on why the mission was not selected and to improve areas of shortcoming.

Q9: Do you think that there is an intrinsic risk associated with sub-K cryogenic missions that could impact the feasibility assessment of proposals for the M8 call?

A9: This is a valid and difficult question. The Science Programme is aware of several potential M missions requiring cooling chains and that this requirement can be a technical hurdle. The area of cooling chains is one ESA takes seriously and where it is exploring concrete technical solutions for the benefit of the community.

ESA is working on defining a set of guidelines for the proposers (as part of the Annex that will be attached to the Call) to address some of the hurdles induced by cryogenic instruments. For example, one could consider a scenario in which ESA handle the cooling down to 4K, with underlying assumptions, and the community takes over at that level. Obviously, the actual feasibility of a mission can only be confirmed by the detailed Phase 0/A studies. The general purpose of the Annex to the Call is to help the proposers in submitting potentially feasible missions that are not immediately discarded from the scientific competition in Phase-1 for programmatic reasons.

Q10: Would ESA make available specific payload information relating to reflector antennas and cryogenic cooling technologies?

A10: We will give guidelines for cryogenic instruments/payloads. The question on reflector antennas is too open to allow a meaningful answer. No dedicated section is foreseen today in the Annex on the specific topic of reflector antennas, beyond the general statement that large and complex antennas or telescopes should be accounted under the ESA CaC and responsibility as part of the space segment industrial development (unless there are very solid reasons for proposing a different scheme).

Q11: Could potential non-ESA Member States / other agencies' contributions be added to the ESA M8 cost cap of 650 million euro or does the full mission need to be limited to this cost cap?

A11: The 650 million euro ​​​​​​​refers to the costs paid by ESA. It does not include the Member State contributions or any contributions by international partners.

Q12: What is the timescale to select the science theme for L5 - as that launches in the second half of the 2040s - knowing the focus of that large mission could influence the M8 science focus?

A12: The Voyage 2050 exercise was a broad consultation with the scientific community, involving almost 100 White Papers, reviewed by five Topical Teams, and analysed and assembled into a series of recommendations by the Senior Science Committee (SSC). The recommendations were endorsed by the Science Programme Committee and have been consolidated in the Science Programme's long-term plan. The SSC identified the scientific themes for the three large Voyage 2050 missions to be: Moons of the Giant Planets (L4), From temperate exoplanets to the Milky Way (L5), and New physical probes of the early Universe (L6). The first of these themes is addressed by the L4 mission for which some activities have already started, with the scientific community and with industry, and are expected to expand after the Ministerial Meeting in 2025. The activities on L5 are planned to start after the Ministerial Meeting in 2025, subject to the level of resources that will be allocated to the Science Programme, and their progress speed will depend on the results of the next two Ministerial Meetings. The themes for the large Voyage 2050 missions are known and the M8 proposals must take this into account.

Q13: For Phase-1 M-class proposal evaluation, can you clarify whether complementarity with other projects would be seen as a plus or otherwise, and if self-contained science output (no need of other data to maximise science return) would be seen as a plus, or otherwise?

A13: If a mission complements another ESA science mission it is considered neither better nor worse than a mission that is independent. A mission should return science that is beneficial to ESA and to the science community. If a proposed mission is doing the same science as a mission that is already approved and will be operational in the same time period, then that could be considered a negative point.

Q14: In terms of the M mission Phase-1 proposal of 10 pages and its expected content, what weighting is applied to the various sections? Is it something similar to EU proposals? e.g. science 50%, implementation feasibility 30%, operations and people 20%?

A14: There are no weighting factors for individual sections. The criteria are scientific excellence and feasible missions. Unfeasible missions are discarded, but the technical assessment is light, in the sense that if there is a reasonable doubt about the unfeasibility or there are ways to improve aspects of the proposal, then the proposal can proceed to the next phase.

Q15: In M7 there were spacecraft mass constraints mentioned, ≤1500 kg dry mass, in view of the ESA cost target. Is this number the same for M8? Will there be similar mass constraints in the Annex?

A15: The Annex accompanying the Call will include guidelines on the mass constraints and it is likely that the numbers will be very similar to the M7 case.

On F and mini-F missions

Q16: Can we accept a larger risk of failure at F and mini-F respectively? Does the given cost reflect an acceptable risk level?

A16: Bearing in mind that these missions are using public money, the approach is always to aim for success no matter what the cost cap is. The expectation for a mission is commensurate with the budget, both scientifically and in terms of complexity. The F missions need a fast timeline and therefore it is advisable to use existing platforms because there is not the time to develop new platforms and because this is a way to lower the risk. All of the Science Programme missions have been successful in orbit so far, and we aim to continue this even with missions that have a shorter timeline and a lower budget.

Q17: How will ESA reduce development overhead for mini-Fast missions? e.g., which requirements/reviews that are demanded for M-class development would be removed from the mini-Fast missions?

A17: There will be a series of reviews with some simplifications. For example, for the F missions there are still most of the standard reviews, but they are run on a faster pace and with fewer inputs. The F-mission schedule requires relying on existing platforms (therefore existing associated documentation, possibly with some modifications), and the payload must rely on demonstrated technologies (TRL ≥ 5) and substantial heritage. If the payload is either already existing or is based on an existing one with small modifications, this means that Phase A/B can be shorter than for M-missions, allowing to initiate the procurement of long-lead items such as detectors and electronics within a couple of years.

For the mini-F Call, we are looking for ideas at this stage. The scientific assessment of potentially feasible mini-F proposals will tell us if such missions have their place in ESA's Science Programme. Clearly, the compressed schedule will require an even higher readiness level than for F-missions, for both the platform and the payload. It is difficult to anticipate the outcome of the mini-F Call, which is precisely why ESA is first proceeding with a Call for ideas. One could conclude there are several valid mini-F mission concepts that could be implemented today, or the opposite, or also that the concept is not immediately feasible but has a good potential subject to a small enabling development programme.

Q18. How will the platform provider be selected for the mini-F? Is ESA open to the Science Community coming together with a consortium that includes a platform provider? Specifically, for a small platform like CubeSats, involving a platform provider already in the proposal stage could better align with the short schedule and the limited cost cap.

A18: Any item that will be proposed under ESA direct responsibility will be procured by ESA in accordance with the general procurement rules of the Agency, by considering, among other things, the Science Programme's specific constraints. This will not affect a fast implementation compatible with the mini-F schedule. The proposers can take a concrete example of platform to build their proposal and achieve a preliminary definition of the interface requirements. However, the proposers cannot choose the final platform if it is intended to be procured by ESA.

Q19: For the mini-F call, how does ESA foresee the approach to geographical distribution? The limited budget and short timeline may imply developing a focused (but impactful) scientific goal. However, this might result in a smaller core team with a narrower geographical spread compared to bigger missions like M or F. Would ESA consider proposals where the core team is formed by one or two countries, provided the mission demonstrates scientific excellence and feasibility?

A19: The geographic distribution of contracts awarded by ESA will consider the Science Programme needs, for the mini-F as for any other ESA procurement. Regarding team composition and parts procured under direct national funding, e.g., payload hardware provision, institute funding, or contribution to operations, there is no minimum number for the countries/entities to be involved. At the same time, some collaboration across the ESA Member States is expected within each proposal.

Equally, there will be no strong constraints on which mission elements could be nationally funded. Scientific excellence and feasibility (including implementation robustness) are the main drivers for building the mini-F proposal.

Q20: In the context of mini-F missions, is it possible to use a payload which is fully developed by an international partner and the ESA Member State consortium would only develop methods/procedures for the 'borrowed' instrument?
Also, for mini-F missions, is it possible to have a payload contribution for these missions from countries outside of Europe?

A20: There is no limitation to contributions from entities and partners outside Europe as part of the proposal. However, the associated implementation risks must be carefully assessed and addressed. Please bear in mind the compressed schedule, implying firm commitments from the very beginning for any partner involvement.

Q21: If a mission is proposed as F-class and deemed scientifically compelling but can fit only in the Cost-at-Completion of an M-class, can it be re-classified as an M-class and carried over for Phase-2 of M8?

A21: The deadline for submitting Phase-1 proposals for the Call for Medium and Fast missions and the exploratory Call for the mini-Fast mission is the same. This is deliberate because it allows us to reclassify a proposal, if necessary. In the past some missions were proposed for one class but a technical assessment by ESA made it clear that based on capability and cost it belonged in a different class. If the proposal is strong enough to compete in Phase-2 it may be reclassified. Bear in mind that the timelines for F and M missions are different (length of time in development; launch dates) and these aspects can be important for the mission's science case.

Q22: Is the maximum payload weight limit (15-20 kg) for mini-F class missions, the total weight or per satellite? Are there any restrictions in size?
​​​​​​​Also, can the call support a project with several small platforms if it fits within the budget?

A22: The only restriction in size is technical feasibility, including among other things the compliance with the interface requirements for the selected launcher. There is no arbitrary constraint on the space segment beyond overall feasibility. Several spacecraft may be proposed for a mini-F provided the mission remains compatible with the budget. However, bear in mind that increasing the number of spacecraft has an obvious impact on cost (hardware and operations) and on the implementation schedule. All proposals are judged on a case-by-case basis.

Q23: Is there a plan to tailor ECSS for the mini-F scheme?

A23: The ECSS is already being tailored to the F missions and there will be some information in the Annex about the applicability to mini-F missions. There is a classification-based approach now and the classification for mini-F's will have fewer constraints for e.g., component selection, but not at the level of compromising performance and losing the science return.

Q24: For F2 the instrument was expected be 'of order less than 70 kg', compared to a spacecraft mass ~500 kg. Is this likely to be the case for F3, and how stringent is this constraint on instrument mass, e.g., can it be higher if the proposers can show that the instrument cost/complexity is under control?

A24: These guidelines on mass are provided to help proposers in meeting the programmatic boundaries, but they are not rigid constraints. If it can be demonstrated that a heavier payload is under control and will work well, it will not be rejected solely because it exceeds the guideline. Equally, a payload can be much lighter than 70 kg, and the mission discarded because of insufficient technology readiness. The primary objective is to have scientifically excellent and feasible missions.

General

Q25: Will ESA provide a list of available platforms, their capabilities, and costs, for F-missions that have to rely on existing platforms?

A25: There is currently no true standard platform for space missions, however there is an initiative at Agency level to investigate such a platform and the Science Directorate will be following the developments in that area.

The term 'available platforms' means using a platform similar to one used for a previous recent mission but perhaps with some modifications. The main idea is to rely on a mass and technical capability that has been used before, where feasible. The actual platform will be in open competition and then industry may decide to repurpose something they have done before. There are also new actors becoming involved in the space industry.

Q26: Can you provide some more clarity about how ESA will oversee the system engineering and interface management for large, complicated payloads?

A26: For relatively complex payloads, involving several Member States, there can be difficult interfaces, both internal to the payload or between the payload and the spacecraft. For these cases, ESA will be in charge of system engineering and the tasks will be under the responsibility of the Prime Contractor. This is happening on LISA now, this is how NewAthena will be handled, and this approach will be followed for all our large/complex future missions.

Q27: I understand that pure technology proposals are not considered, but what about a pathfinder for future L-class missions?

A27: All feasible proposals are judged on the science case. If the science is weak, then even a pathfinder justification would not be sufficient for the proposal to be selected.

Q28: Can you give indicative cost for operations?

A28: Operations costs vary from one mission to another and according to the type of mission, e.g., planetary or observatory. A ballpark figure for the spacecraft and science operations would be ~10-12% of the total mission cost for the F case, and ~14% for the M case. Indicative amounts will be included in the Annex issued at the time of the Call. The relative numbers have not changed since the previous Call but they have been updated taking inflation into account.

Q29: Could you please clarify what is meant with "potential technical feasibility"?

A29: The Future Missions department will perform a technical review for each submitted proposal and report on this to the Science Assessment Panel (SAP) and the Science Assessment Review Panel (SARP) to inform their recommendations at the different stages of the selection process. Technical feasibility is solidly established at the end of the Phase A only, although it is generally reached (or well advanced) at the end of the Phase 0, when the spacecraft and payload preliminary baseline, and mission requirements, are established. As already mentioned, the Phase-1 feasibility assessment is deliberately light. For Phase-2 selection, complete proposals are assessed, and the feasibility remains "potential". However, there must be high confidence that the mission will be feasible and will successfully pass the Phases 0 and A. The definition of descoping options and of the minimum science objectives are important to assess the design flexibilities, which can be crucial for ensuring feasibility.

Q30: Can F missions target any body in the Solar System (in principle)? In other words, is there a limitation on when the mission ends?

A30: Any Solar System body can in principle be targeted if the mission can be done within the technical and cost constraints. For missions to outer Solar System bodies the cost of operations during any long cruise phase is included in the total cost. For the current F missions in development, the nominal science operation lifetime is about two years.

Q31: Are lunar science and the Moon as a destination within the scope of the Science Programme?

A31: There is no limitation in terms of Solar System destinations. A proposal for a lunar mission with a strong science case is welcome.

Q32: How much overlap can there be in the science with Earth Observation?

A32: There are some areas that overlap, for example, the science of the Earth's magnetosphere. A mission proposal that investigates e.g., the Sun-Earth connection or plasma physics in the environment of the Earth, would be considered a science mission.

Q33: In Phase-1, are all proposals reviewed by the SAP or only the proposals that pass the technical assessment?

A33: The scientific and technical reviews are run in parallel. Before the SAP prepare their final report, they receive the technical assessment and if this demonstrates that a proposal is not feasible then that proposal does not proceed further in the science review.

Q34: How many proposals are usually received at every call?

A34: In the past, 20-30 proposals have been received for Phase-1 for each class (F or M), which dropped to 5-10 for the Phase-2 proposals (after technical and scientific assessments). These are "as observed" numbers: there is no limitation on the number of Phase-2 proposals.

Q35: Would you describe the mindset during scientific evaluation as rather conservative, or risk-tolerant? E.g., is a series of experiments for testing several promising fundamental theories eligible for M-type?

A35: For Phase-1, the assessment is not conservative. Any proposal that has potential to deliver excellent science and is potentially feasible, will proceed to Phase-2. The Phase-2 proposals will be ranked scientifically, and the Senior Science Committee will compare the science cases. If the proposal is competitive, it is eligible.

Q36: Does ESA propose tools to estimate the carbon budget for space projects, which the community could use?

A36: There are some preliminary tools being considered in the Agency, during the study and implementation phases. The carbon budget is not considered for the selection of mission candidates.

Q37: Does it matter if some members of a proposing team hold citizenships from non-ESA Member States?

A37: It does not matter. Obviously, these members must be able to fulfil their job as part of the team, i.e. their function must be compatible with their nationality (e.g. for Export Control aspects if applicable or national rules).

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