NASA?s Next Generation Launch Vehicle Technology Program has an interest in robust TPS materials with the highest level of thermal performance at the lowest possible areal weight. The materials need to be oxidatively stable and insensitive to water vapor, and able to perform with a minimum of material hysteresis over many cycles. Flexible silica aerogel composites, a class of super-insulation material recently developed by Aspen Aerogels, has not been utilized before in high temperature TPS designs. Thermophysical characterization data will be collected during the Phase I program for high-temperature durable, oxidatively stable, flexible aerogel composites at different densities, pressures and temperatures. The test data will be useful for re-entry TPS sizing studies, using existing aeroframe design and affiliated heat loads and environmental conditions for the re-entry trajectory. The materials optimized in the Phase I program will be available for thermal testing at NASA Langley under conditions relevant to Earth re-entry by reuseable launch vehicles for the coldest layers of the TPS system. Aerogel augmented TPS designs are likely to save significant parasitic TPS weight compared to the most promising non-aerogel alternatives available today. The aerogels will be compatible with all high temperature capable face-skin materials.