THE OVERARCHING GOAL OF THIS PROGRAM IS TO DEVELOP AND DELIVER A PLATFORM FOR SCALABLE FABRICATION AND OPTIMAL DESIGN OF ULTRA-HIGH PERFORMANCE CERAMIC AND METALLIC TRUSS CORE SANDWICH PANELS FOR LARGE-SCALE (10 S OF METERS) THERMO-STRUCTURAL SPACE APPLICATIONS. THE KEY SCIENTIFIC INNOVATION IS THE INTEGRATION OF MODELS AND EXPERIMENTS AT MULTIPLE SCALES TO ELUCIDATE THE DEPENDENCE OF MECHANICAL/ THERMAL PROPERTIES OF CERAMIC AND METALLIC LATTICES ON MANUFACTURING PARAMETERS/DEFECTS AND TOPOLOGY. THIS SCIENTIFIC UNDERSTANDING WILL POSE THE BASIS OF PREDICTIVE PERFORMANCE MODELS THAT WILL BE USED IN OPTIMAL DESIGN TOOLS. THE PROPOSED OPTIMIZED DESIGNS WILL POSSESS EXCEPTIONALLY HIGH SPECIFIC STIFFNESS AND STRENGTH LOW THERMAL CONDUCTIVITY SUFFICIENT TOUGHNESS FOR STRUCTURAL APPLICATIONS AND CAN BE MANUFACTURED IN CURVED AND COMPLEX SHAPES. A PARTICULAR IMPLEMENTATION BASED ON THIS CONCEPT WOULD RESULT IN A LOADBEARING STRUCTURE WITH DEBRIS AND MICROMETEORITE SHIELDING PERFORMANCE SUPERIOR TO SOA PARASITIC D/M SHIELDS (E.G. WHIPPLE SHIELDS) POTENTIALLY RESULTING IN DRAMATIC WEIGHT SAVINGS AT THE VEHICLE LEVEL. THE PROPOSED TECHNOLOGY LEVERAGES EXPERTISE AT UCI IN MODELING CHARACTERIZATION AND OPTIMAL DESIGN OF MICRO-ARCHITECTED MATERIALS WITH EXCEPTIONAL THERMO-STRUCTURAL PROPERTIES AND BUILDS UPON TWO KEY ADDITIVE MANUFACTURING INNOVATIONS RECENTLY DEVELOPED BY OUR CO-PIS AT HRL LABORATORIES: (I) A NOVEL PHOTOPOLYMERIZABLE PRE-CERAMIC RESIN THAT PYROLYZES TO SIOC AND IS COMPATIBLE WITH ALL STEREOLITHOGRAPHY-TYPE PROCESSES (A SIC PRECURSOR IS CURRENTLY UNDER DEVELOPMENT) AND (II) THE SELF-PROPAGATING POLYMER WAVEGUIDE (SPPW) FABRICATION PROCESS WHICH ENABLES ROLL-TO-ROLL FABRICATION OF MICRO AND MACRO-LATTICE CORES OVER NEARLY UNLIMITED DIMENSIONAL CONSTRAINTS IN TWO DIRECTIONS; THESE CORES CAN BE POST-PROCESSED INTO HOLLOW METALLIC OR SOLID CERAMIC TRUSS CORE LATTICES. IN ORDER TO SUCCESSFULLY APPLY THESE TECHNOLOGIES FOR THE NASA-RELEVANT APPLICATIONS DISCUSSED ABOVE THE FOLLOWING SCIENTIFIC QUESTIONS NEED TO BE ANSWERED: (I) HOW DO PROCESSING PARAMETERS (E.G. PYROLYSIS TEMPERATURE) AND FEATURE DIMENSIONS (E.G. STRUT DIAMETER) AFFECT THE MICROSTRUCTURE OF THE SIOC STRUTS AND IN TURN THEIR MECHANICAL (STRENGTH STIFFNESS) AND THERMAL (CONDUCTIVITY) PROPERTIES? (II) WHAT ARE THE EFFECTS OF THE MATERIALS AND MANUFACTURING UNCERTAINTIES ON THE MECHANICAL PROPERTIES OF THE TRUSS CORE MATERIAL? (III) HOW DO SOLID CERAMIC TRUSS LATTICES COMPARE TO HIGHER-TRL HOLLOW METALLIC TRUSS LATTICES IN TERMS OF SPECIFIC STRENGTH FRACTURE TOUGHNESS AND THERMAL CONDUCTIVITY? (IV) WHAT ARE THE FAILURE MODES OF CERAMIC TRUSS CORE SANDWICH PANELS WITH CMC FACE SHEETS LOADED IN BENDING AND TRANSVERSE SHEAR? (V) WHAT IS THE BEHAVIOR OF THE CERAMIC TRUSS CORE DURING HYPERVELOCITY IMPACT WITH DEBRIS OR A MICRO-METEORITE? IN PARTICULAR CAN THE TRUSS CORE SOLVE THE CHANNELING PROBLEMS THAT PLAGUE HONEYCOMB CORES WHILE MAINTAINING SUFFICIENT ROBUSTNESS AFTER IMPACT? (VI) CAN EXISTING TOPOLOGY OPTIMIZATION TOOLS BE EXTENDED TO INCORPORATE ANSWERS TO THE QUESTIONS ABOVE AND ADDRESS THE COMPLEX MULTI-FUNCTIONAL OPTIMIZATION PROBLEMS THAT ARE INHERENT IN THE MOST CRITICAL NASA APPLICATIONS? IN THIS PROGRAM WE PROPOSE TO ANSWER ALL THESE SCIENTIFIC QUESTIONS THROUGH A SYNERGISTIC INTEGRATION OF FABRICATION CHARACTERIZATION MODELING AND OPTIMAL DESIGN TASKS. THE FINAL OPTIMAL DESIGNS WILL BE FABRICATED AND TESTED AT THE LABORATORY SCALE BUT USING A PROCESS THAT CAN SCALE UP TO NASA-RELEVANT DIMENSIONS. DISCUSSIONS WITH NASA ENGINEERS THROUGHOUT THE PROGRAM WILL HELP DEFINE THE MOST RELEVANT SET OF REQUIREMENTS AND SUGGEST ALTERNATIVE/ADDITIONAL DESIGN STUDIES.