Flexible Phenolic Intermingled Carbon Ablators (PICA-Flex)

Flexible PICAs combine both carbon and phenolic fiber constituents during a felting process rather than introducing a phenolic through infusion processes that also uses harsh chemicals. MERINO PICA-Flex materials drastically reduces integration complexities when compared to traditional phenolic infused rigid tiles, and can eliminate the costly and time intensive phenolic infusion process, resulting in a thermal protection system (TPS) material more akin to a “blanket” than a rigid TPS. PICA-Flex encompasses a range of configurations, including a dual layer PICA-Flex material with a higher density outer layer(s) to minimize recession, a lower density PICA-Flex material with applicability to aftbody TPS, and a single piece PICA-Flex forebody. PICA-Flex is fabricated by combining by intermingling both carbon and phenolic fiber constituents during a needle punch felting process during which the fibers are made into battings, and the battings are needled together layer-by-layer to build up thickness. For the past three decades, phenolic impregnated carbon ablators (PICAs) have been the state of the art in ablative entry materials for heat shields for Mars and Earth sample return missions for entry conditions. Traditional rigid PICAs have very low density and highly efficient ablative capability to provide mass efficiency for these heating regimes. Non-rigid variants of PICA provide additional benefits beyond traditional rigid PICA, offering reduced density variants with increased strain to failure. However, all three materials require lengthy infusion processes involving complex equipment and infrastructure, yield toxic byproducts, and the rigid thermal protection system (TPS) produced requires complex and costly integration processes. NASA Ames has developed a family of materials called Materials Engineered for Re-entry using Innovative Needling Operations (MERINO), a flexible PICA material based on felting and fiber intermingling techniques that can create a blanket of thermal protection material to install onto spacecraft.