DETERMINATION OF THE MARGIN OF SAFETY IN THE THERMAL PROTECTION SYSTEM SIZING PROCESS

This paper presents a review of the dimensioning methods of thermal protection systems for spacecraft. Classic methods are based on a stacked worst case or rootsum-square method, whereas probabilistic methods define a correlation between the thickness margin and the probability of the occurrence of an over-temperature of the substructure. A probabilistic sizing case is presented for the Stardust mission. With a probabilistic approach to quantifying the thermal protection system response, one can identify the main sources of uncertainty to decrease the heat shield mass fraction. Identifying the most appropriate methodology can allow a proper connection between the margin of safety and overall reliability of the heat shield.