Selection and Preliminary Sizing of an Ablative TPS for Lunar Re-Entry Mission

One of the major technological issues for a planetary entry mission is related to the identification of thermal protection materials compatible with the predicted Environmental Heat Load for the different exposed reentry vehicle surfaces. According to the Apollo mission experience, the maximum heat flux experienced by a vehicle returning from a lunar mission is about 5 MW/m2. This value is not compatible with the reusable TPS developed for the vehicle returning from LEO mission and ablative materials have to be introduced. The paper describes a preliminary investigation on the compatibility of the existing ablative material with the Environmental heat load calculated in the frame of the Moon & Mars Human Mission Re-entry Technologies study for both Biconic and Slender Body vehicle shape. On the basis of the most promising material selected, a preliminary thermal protection design compatible with the manned mission requirements for both vehicle shapes has been proposed and justified by functional and thermal analyses.