IGF::OT::IGF THIS PROGRAM ADDRESSES THE NEED TO MONITOR SURFACE RECESSION, TEMPERATURE, AND THROUGH-THICKNESS PROPERTIES OF THERMAL PROTECTION SYSTEM (TPS) MATERIALS. THESE TPS MATERIALS HAVE UNIQUE PROPERTIES FOR SHEDDING THE HEAT GENERATED UNDER REENTRY CONDITIONS TO PROTECT THE INTEGRITY OF THE SPACECRAFT. HOWEVER, EVER-INCREASING MISSION DEMANDS REQUIRE IMPROVED PERFORMANCE AND A BETTER UNDERSTANDING FOR MODERN HEAT SHIELD STRUCTURES. THIS CAN BE ACCOMPLISHED WITH A NONINVASIVE, NONDESTRUCTIVE METHOD THAT USES PROJECTED SENSING FIELDS THROUGH THE THICKNESS OF THE TPS MATERIAL. NOVEL EDDY CURRENT METHODS ARE PROPOSED THAT INCORPORATE INNOVATIVE SENSOR ARRAY CONSTRUCTS, PHYSICS-BASED MODELS, AND MULTIVARIATE INVERSE METHODS TO NONDESTRUCTIVELY ASSESS CARBON-BASED TPS MATERIALS SUCH AS PHENOLIC IMPREGNATED CARBON ABLATOR (PICA). THE SENSORS CAN BE MOUNTED BEHIND THE TPS MATERIAL OR EMBEDDED WITHIN THE TPS WITH SENSING MAGNETIC FIELDS THAT ARE PROJECTED THROUGH THE MATERIAL.