Thermal Protection System (TPS) for Agressive Reentry Trajectories of Space Vehicles

Structural C foam lightweight heat shield sandwich panels for use in a next-generation, high-performance thermal protection systems have been previously tested at NASA Ames Research Center under the pullout and glide portions of a simulated extended-range reentry trajectory. Outstanding performance has been demonstrated, with no ablation of the heated surface to heat fluxes of 150-450 Btu/ft2xsec and durations of 255 seconds using a SiC composite non-ablative coating on a lightweight structure. Unfortunately, pore size and density control of these materials is currently inadequate, and facesheet bonding and water adsorption resulted in reliability issues and areas for improvement. The proposed low-cost, lightweight thermal protection system will utilize a SiC composite coating as the hot side ablation resistant coating, deposited directly on low thermal conductivity carbon and/or glassy silicon carbo-nitride foam, yielding a final areal density of »1.0-1.2 lb/ft2. The innovation to be demonstrated in the proposed program is the integral production of a castable, rigid, microcellular carbo-nitride foam structure having optimizable thermal and mechanical properties which can be coated directly to a SiC composite ablation resistant coating system.