The Evolution of the MSL Heatshield
Driver, David M.
Slimko, Eric M.
Beck, Robin A. S.
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The MSL entry vehicle will be experiencing aerothermal environments that no previous Mars entry vehicle has seen, and as such, will require a heatshield that no previous Mars entry vehicle has flown. Early assessments of the environments led engineers down the path to "fly as we've always flown", with the heritage Mars heatshield material, SLA-561V. Screening tests in arc jet facilities in stagnation model configurations substantiated the claims that the SLA-561V could survive high heating rates expected on the heatshield, albeit, with a melting surface. However, due to the size and mass of the vehicle, along with the need to reenter at angle of attack, high heating and high shear in turbulent flow was predicted on the leeward side of the vehicle. Testing in shear showed that the SLA-561V exhibited catastrophic ablation which led to the abandonment of the material for this application and the fast-tracked development of a tiled PICA heatshield design, on track for a 2009 launch.