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GRaphical Interface for reliability Forecasting
As Head of the Reliability and Safety Department at the French Space Agency (CNES), Sébastien Bosse shares his experience with the GRIF software suite, used to model a complex space system composed of a satellite, ground antennas, and terrestrial telescopes.
With a degree in Applied Mathematics and a specialization in financial risk, Sébastien Bosse began his career at a Toulouse-based company specializing in reliability engineering. He later joined CNES, where he spent about ten years analyzing critical systems. After a three-year assignment in French Guiana focused on radar systems and real-time telemetry data processing, he returned to the Toulouse Space Center in 2023. Today, he leads the Reliability and Safety Department.
How did you discover the GRIF suite?
Sébastien Bosse: I first encountered this software suite during my engineering studies in Applied Mathematics. We used it in practical sessions, mainly to calculate failure orders using Markov chains or to model systems with Petri nets. It’s an extremely reliable and powerful tool, and I immediately saw its potential for complex applications.
What prompted you to integrate GRIF into your projects at CNES?
S.B.: For a long time, CNES used a solution developed by a space engineer who knew our needs inside out and adapted the tool accordingly. But in 2016, after a comprehensive comparison of available tools, we decided to switch to GRIF. I was already familiar with it and had full confidence in the robustness of its calculations and the accuracy of its results. Behind the tool is also a highly skilled and responsive team that ensures both its sustainability and continuous improvement. This transition coincided with a concrete modeling project for a complex space mission.
"GRIF is used by
major industrial
players, including
TotalEnergies, which
ensures its ongoing
development."
What challenges did GRIF help you overcome?
S.B.: The project involved a space mission to observe random events—specifically gamma-ray bursts, which occur during phenomena like star explosions.
The observation system included a low-Earth orbit satellite to detect these bursts and transmit their coordinates to large ground-based telescopes for real-time observation. This transmission chain involved several components: a satellite, a network of around forty VHF (very high frequency) ground antenna stations, and telescopes.
GRIF enabled us to model the availability of the ground stations, potential failures, maintenance, satellite orbitography, and detection uncertainties. The ultimate goal was to validate the technical and economic feasibility of the mission, with specific performance targets. Using the Petri module, we ensured the proper sizing of the station network and its maintenance policy, and we defined precise reliability requirements for industry partners—both for ground equipment and the satellite.
In your opinion, what are GRIF’s main strengths?
S.B.: I’d say the accuracy of its calculations, the richness of its modeling modules, and the adaptability of the software suite. The Petri module allows us to tackle very complex systems with analytical rigor and reliable calculations that truly inform our decisions. Another key point is its longevity. GRIF is used by major industrial players, including TotalEnergies, which ensures its ongoing development. The support team is also very responsive—we get near-instant answers to technical questions or specific training requests.
Do you plan to use GRIF for other projects?
S.B.: Absolutely. For relatively simple systems—like a single satellite—reliability block diagrams are sufficient. But when dealing with satellite constellations involving deployment and/or renewal challenges, or complex maintenance chains, GRIF becomes essential. Since I first used it in 2008, I’ve seen the tool evolve significantly. Calculations are faster, and the interface is more intuitive, graphical, and interactive. It’s a very enjoyable tool to use, especially for those of us who love modeling!
Any final thoughts?
S.B.: We regularly participate in GRIF Day, an event that brings together the user community. It’s a great opportunity to share best practices, use cases, and suggest new features. GRIF’s applications span many industrial sectors, and it’s always valuable to stay up to date with technological developments.