Penetration equations for thermal protection materials

NASA has developed a number of penetration equations for a broad range of thermal protection system (TPS) materials used on the Space Shuttle Orbiter and other spacecraft including low-density ceramic tiles, reinforced carbon-carbon, flexible ceramic insulation and multi-layer insulation (MLI). The penetration equations describe the penetration depth or damage extent to be expected from hypervelocity particles as a function of projectile velocity, size, density, and various target parameters including thickness and configuration. ''Ballistic limit'' equations have also been developed to define projectile conditions causing threshold perforation of more complex targets that combine an outer TPS material with an underlying structural element such as a ceramic tile bended to an aluminum plate. These equations were developed from hypervelocity impact data collected at the NASA Johnson Space Center (JSC) Hypervelocity Impact Test Facility (HIT-F).