Development of the Mars Science Laboratory Heatshield Thermal Protection System

Early in the development of the Mars Science Laboratory thermal protection system on the heatshield, project management planned to use Lockheed Martin’s Super Light Ablator in honeycomb as the ablative material based on successful use on previous Mars entry heatshields and on stagnation arcjet tests at heating rates beyond the design levels. Because this heatshield would be the first to experience combined turbulent flow and high shear environments as it entered the Mars atmosphere, tests were performed in various arcjet facilities on flat-plate, wedge, and swept-cylinder specimen configurations in order to ascertain the effects of shear on the material. During the course of these tests, a set of conditions within the flight envelope was identified that resulted in catastrophic failure in the SLA-561V. Consequently, project management decided to replace the SLA-561V with the phenolic-impregnated carbon ablator, the material that had flown successfully on the Stardust mission and was undergoing intense tes...