Flexible Gap Filler for Ablative Thermal Protection Systems

NASA's Orion spacecraft will serve as the exploration vehicle that will carry a crew to space, provide emergency abort capability, sustain the crew during the space travel, and provide safe re-entry from deep space return velocities. Planetary aerocapture and entry requires that the crew vehicle be equipped with a Thermal Protection System (TPS) comprised of lightweight, high performance ablator materials. Materials current under development include felt or woven material precursors impregnated with polymers (i.e. PICA) and/or additives to improve ablation and insulative performance, along with the block form of Avcoat ablator. There is a need for advancements in polymers for use in bonding and/or gap fills for tiles of advanced TPS for extreme entry conditions. The ideal binder would be a flexible, low glass transition temperature polymer with a high decomposition temperature/char yield (comparable to phenolic) and a high (>1%) strain-to-failure that is compatible with cured epoxy, phenolic, and/or cyanate ester. Engineers at Luna have developed a novel copolymer elastomer that has a very low glass transition (< -100 degrees F) and a decomposition temperature on par with typical phenolic ablatives. This resin can be highly filled to tune ablative properties and is compatible with glass and carbon fabric substrates.