Post-Flight Evaluation of Stardust Sample Return Capsule Forebody Heatshield Material

Phenolic Impregnated Carbon Ablator (PICA) was developed at NASA Ames Research Center under the lightweight ceramic ablator development program in the ’80s. PICA’s low density (~ 0.27g/cc), coupled with efficient ablative capability at high heat fluxes, makes it an enabling technology for the Stardust mission. This paper discusses the evaluation of three cores extracted post flight from key locations on the forebody heatshield of the Stardust Sample Return Capsule (SRC). Core locations included a near stagnation core, a flank core, and a segment taken from the shoulder of the heatshield. Evaluation included density profiles, recession determination, a thermal analysis profile, PICA bondline examination, strength assessment of remaining virgin PICA, an emissivity profile, a chemical analysis profile, and a microstructural analysis. Results show good agreement in comparisons of experimental density profiles and profiles derived from FIAT and in recession comparisons from measured values and FIAT predictions for the flank core. In general, the PICA material examined in the cores is in good condition and intact. Impact damage is not evident, and the only degradation observed was that caused by heating on entry. A substantial amount of virgin PICA was present in all cores examined.