The EFESTO project: design, development and testing of the inflatable structure and its ground demonstrator

International audience ; The European Union H2020 EFESTO project has as end goal the advancement of the European Technology Readiness Level (TRL) of Inflatable Heat Shields for atmospheric entry vehicles from 3 to 4/5, thereby paving the way towards flight (TRL 6 with a future In-Orbit Demonstration). Two different applications have been identified and studied within the scope of the project. The first application considers a 2.5-ton Mars payload destined for a Mars Orbiter Laser Altimeter (MOLA) target altitude of +3 km. The Mars application combines a 9-meter diameter Hypersonic Inflatable Aerodynamic Decelerator (HIAD) with a Supersonic Retro-Propulsion system. The second application addresses re-entry and recovery of the first stage of an orbital launcher, using the AVUM upper stage of the Arianespace VEGA vehicle as baseline study case. For both applications, the EFESTO project devoted a significant effort to maturating the two key technologies that constitute the core of Inflatable Heat Shields, i.e., the Flexible TPS and the Inflatable Structure. This paper provides insight into the design of the EFESTO Inflatable Structure for both Mars and Earth applications, as well as into the development and testing of a Ground Test Unit (GTU). Particular attention is given to discussion of the design, fabrication, integration, and test of the 1:2-scale Inflatable Structure GTU, and how the experimental results have been used to improve the numerical prediction capabilities. This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 821801.