About Ratio-Sim
This page provides further details about RATIO-SIM, its structure (Advisory & Working Groups), its terms of reference, and other related ESA material such as Technology Harmonisation Dossiers.
Advisory Group
The RATIO-SIM Advisory Group is composed of ESA Member States key stakeholders in the field of system modelling and simulation such as Large System Integrators like Airbus Defense and Space, Thales Alenia Space, ArianeGroup and Agencies like CNES, ESOC and ESTEC. The Advisory Group reviews current roadmaps, guides the R&D activity plans and monitors their execution, as to maximise results towards a shared vision, this includes:
- Providing strategic guidance and oversight to the RATIO-SIM initiative;
- Ensuring alignment of RATIO-SIM activities with the broader objectives of RATIO-SIM stakeholders;
- Facilitating collaboration and information exchange among stakeholders in the field of system modelling and simulation;
- Reviewing and approving workplans and deliverables of the Working Groups;
- Supporting the dissemination and adoption of RATIO-SIM standards, guidelines, and best practices across the European space community.
The RATIO-SIM Advisory Group and its Working Groups are open to participation by organisations residing in any of the ESA Member States and that are stakeholders in the domain of system modelling and simulation. Details are provided in the RATIO-SIM Terms of References.
Simulation Modelling Platform
The Simulation Modelling Platform (SMP) Working Group is responsible for simulation modelling and model portability aspects including standardisation. This SMP Working Group took onboard the existing SMP Level 1 ECSS Working Group and continue the work on SMP with the same community; however now in the wider context of RATIO-SIM.
The first issue of ECSS-E-ST-40-08C (SMP level 2) was published on 5 August 2025, together with Revision 1 of ECSS-E-ST-40-07C (SMP level 1).
Simulator Architecture
The Simulator Architecture Working Group is responsible for the URSA (Unifying Reference Simulator Architecture) reference architecture including information flow and engineering processes. URSA is an attempt in unifying well used specification and architecture from both CNES and ESOC ground segments.
Simulator Infrastructure
The Simulator Infrastructure Working Group is responsible for developing building blocks for the existing simulator infrastructures in European agencies and industry. These building blocks will enable interoperability between various Simulator Infrastructures and Mission Control Systems. As an example, a first activity will focus on the High Level Architecture (HLA) specification and how its European implementation can be a first key to this interoperability.
Onboard Computer Simulators and Emulators
The Onboard Computer Simulators and Emulators Working Group is a response to the upcoming challenges in the emulation and simulation of onboard computers. The WG will focus on the definition of a common strategy for Europe to address the needs of future missions, including the definition of a handbook to advise on the best choice of technology per simulation use-cases and needs.
Digital Twin and Advanced Simulation Concepts
The Working Group aims at coordinating the vision, objectives, components, use cases and scope/landscape of the Digital Twin Spacecraft. In more details the following objectives are envisioned:
- Define the concept of Digital Twin Spacecraft for the European industry, organizations and agencies in the scope of Europe Programmers
- Define the European strategy for the development and deployment of the technologies
- Ensure that the capabilities provided by the technologies are available to the industry and supported by the agencies
- Coordinate and demonstrate enabled capabilities of deployed technologies. Provide a forum to demonstrate prototypes, generic components and enabled capabilities
- Define and Harmonize Digital Twins & Advanced Simulation Concepts (e.g., AI, surrogate models, ...) generic components, architectures and applicability of standards
- Define sets of guidance for manufacturing and systems and software development
RATIO-SIM Terms of Reference
The RATIO-SIM Terms of Reference document provides detailed information on the objectives, structure, roles and responsibilities, membership criteria, and operational procedures of the RATIO-SIM initiative. It serves as a guiding document for all participants and stakeholders involved in RATIO-SIM activities.
The Terms of Reference document is available for download: Terms of References
ESA Technology Harmonisation
RATIO-SIM evolves alongside ESA Technology Harmonisation cycles. Our ESA Technology Harmonisation Dossier is System Modelling and Simulation, last updated in 2023.