The MELiSSA project consists of developing a closed-loop life support system (LSS), allowing astronauts to recycle crew waste, revitalize air and produce water and food. That will make remote exploration missions possible by reducing the spacecraft's mass, but those regenerative technologies are also destined for terrestrial contexts.  There is an increasing need to develop a complete simulation platform for the MELiSSA loop. That implies considering a multi-criteria approach to provide the user with metrics complementary to the traditional Equivalent System Mass (ESM).  State of the art was conducted on previous LSS projects to identify the challenges around the specification of such a simulation platform. Many similar projects have struggled in the past for technical, political, and human reasons, such as ELISSA and V-HAB. That can be explained by the technical complexity of the problem and the poor consideration of stakeholders' needs during the specification phase. In addition, the MELiSSA simulation platform has to consider its specificities in circularity, which can relate to similar challenges in terrestrial circular systems. An in-depth industrial audit with several MELiSSA project stakeholders enabled their simulation needs to be understood. Some tools already exist, such as ALiSSE, a multi-criteria evaluation tool. However, the industrial audit revealed a complex use and variability in the reliability of the criteria due to difficulties in integrating the external simulation models. After several expert interviews, we represented their needs from 3 different viewpoints (Operational analysis, System Architecture & Use case), highlighting existing tools and conflicting priorities (trade-off between flexibility, speed, and reliability). It showed the need to implement new methods to ensure the consistency and usefulness of the final simulation platform. In particular, we have identified a gap between the formulation of system architecture simulation requirements and simulation models. To bridge this gap, we consider here two complementary approaches extracted from the literature:  The "simulation request": to define the needs and causes of each simulation in a transparent and traceable way. It is enriched with "Model Identity Cards" (MIC), a collaborative standard that simplifies simulation models specification sharing and interfacing;  The "Credible Simulation Process" approach allows a project manager to anticipate the resources and roles needed for each step of the specification process.  These two approaches would be interesting to integrate into the MELiSSA project, as they would allow each stakeholder to use the same standard of requirements and architecture via a top-down approach. Simplified templates for applying them have been created. That contributes to spreading their interest among the project stakeholders with a view to standardization, connectivity, traceability, and digital continuity.  Through this research, simulation architecture specification methods have been identified to address the project's needs at different levels of detail and technicality. These methodologies have been analyzed and discussed, proposing perspectives for future research within the MELiSSA project.