GRIF at the European Space Agency (ESA) RAMS* Conference in the Netherlands

You invited GRIF to ESA's second RAMS conference. Why did you do this?

Fabrice Cosson: The first reason is that, as RAMS manager, I'm constantly on the lookout for tools and methods that can improve the operational reliability of our missions. The second reason is much more pragmatic. For some years now, the calculation tool used by ESA and other space industry players has no longer been maintained. This led us to look around the market to identify all possible alternatives. There are very few tools adapted to our needs, and GRIF offers a relevant solution for complex calculations using Petri nets. Hence our invitation to take part in our second RAMS conference, which brought together almost 120 participants from industry, academia, CNES, NASA and DLR, representing 14 different nationalities.

What are GRIF's strengths?

Fabrice Cosson: The Petri module, which enables precise modeling for reliability and availability analyses. In addition, the fact that GRIF is supported by a major group like TotalEnergies guarantees its long-term viability. We're interested in a tool like this to calculate the complex reliability and availability of constellations such as Galileo, which has around thirty satellites, or future telecommunications satellite constellations.

What is your feedback on the RAMS 2024 conference?

Fabrice Cosson: The GRIF stand - already present at the ESREL 2023 conference in Southampton - and Maïder Estécahandy's presentation aroused real interest. After having tested the tool, I thought it would be interesting to continue to exchange ideas and open the doors of the conference to a software that is quite unique on the market. We've achieved our objectives: fostering collaboration between industry and universities, identifying research topics, and understanding new issues related to Dependability. Inviting GRIF also means opening up to a business sector other than space, and finding synergies. 
The conference was also an opportunity to reflect on new approaches to reliability prediction (FIDES, etc.), the role of AI, and the contribution of Dependability to the space industry's "zero debris" policy.
 

Background – Over the next decade, a growing number of satellite constellations will be orbiting the earth. These constellations, essential for global communications and Earth surveillance, raise new challenges linked to orbital debris and congestion in critical orbits. Their growth calls for a strategic approach to their deployment and sustainability. 

Simulating with Petri nets – Several deployment scenarios are studied and presented on the CNES r station. They take into account factors such as satellite type and quantity, in-orbit inventory management, satellite and launcher reliability, and renewal frequency. A simulation approach is used to analyze the impact of these parameters on system performance. Petri nets, a mathematical and graphical tool for modeling discrete-event systems, are coupled with Monte-Carlo simulations to optimize the constellation's deployment and renewal strategy.

The result – During phase 0 of the project, the simulation model enables a comprehensive comparison of performance and cost measures in several scenarios. The benchmarking aims to optimize service availability based on satellite spares, in-orbit inventory management and renewal strategies.