Performance of a Low Density Ablative Heat Shield Material

摘要

An evaluation of the Stardust spacecraft forebody heat shield design was conducted to address uncertainties in original development and qualification efforts. Results are reported for additional arc jet tests and analyses done on the ablative and thermal performance of the low density ablative material used in the Stardust design for conditions simulating nominal peak convective heating conditions expected for Stardust sample return capsule Earth entry. Test data were used to adjust iteratively the thermophysical properties in an ablative response computer code to match experimental in-depth temperatures. Ablative recession rates and maximum internal temperatures were satisfactorily predicted by the computer code using derived properties for nominal peak entry heating rates and for rates 37% greater than nominal. Experimental and computer model maximum internal material temperatures were in agreement over a range of conditions and are considered to validate the Stardust heat shield design although measured in-depth temperature data show consistent temperature rise deviations that are not accurately modeled by the computer code. Predicted Stardust heat shield performance based on these results indicates that maximum attachment bond line temperatures will be considerably less than the maximum allowable of 250C, and total recession will be a small fraction of the as-designed thickness.