This research proposal seeks to improve the state of the art in the modeling and simulation of ablating thermal protection systems (TPS). It will accomplish the modeling goals by taking physics based approaches to the governing equations, and using sensitivity analysis to identify key processes and mechanisms for study. Additionally, it will work to couple all new capabilities developed to a well validated high fidelity computational fluid dynamics code (US3D). Finally, it will investigate the feasibility of performing fully coupled full trajectory simulations using capabilities developed in the research.. These goals are consistent with NASA's continued investment in improving aerothermal simulation tools, and are en essential part of creating the enabling technologies required for future exploration missions.