In-Situ Fabrication of Spacecraft Thermal Protection Systems

Current state-of-the-art (SOTA) methods for the fabrication of thermal protection systems (TPS) for spacecraft is costly, labor-intensive, and limited to on-Earth production. To address these shortcomings, Mainstream, in collaboration with the Design, Research, and Education for Additive Manufacturing Systems (DREAMS) lab at Virginia Tech (VT), proposes to develop a large-format additive manufacturing (AM) system for the in-situ fabrication of a high-heat-flux ablative TPS. The Spacecraft Thermal protection system Additive Manufacturing (STAM) system will consist of a large robotic arm coupled with a direct ink write (DIW) printhead and integrated UV lamp for the large area deposition of a filled thermoset, such as cyanate ester, phenolic, or epoxy-based resin with carbon-based fillers and photoinitiator. This configuration will allow for the precise and reproducible deposition and in-situ curing driven by the curing of the photoinitiator and a secondary thermal reaction through frontal polymerization to cure the TPS layer fully. The STAM system will feature a 6 degree of freedom (DoF) robotic arm with one external axis (a turntable to rotate the spacecraft) to allow for conformal deposition over the entire surface of a spacecraft with up to a 5-m diameter base and a dual-chamber printhead to extrude the 2-part thermoset via a progressive cavity pump. The STAM system will autonomously fabricate a full-scale conformal TPS in-situ cured by two sequential reactions activated directly after deposition without a post-process thermal cure.