Initial Assessment of Mars Science Laboratory Heatshield Instrumentation and Flight Data

Abstract

The Mars Science Laboratory (MSL) Entry Descent and Landing Instrumentation (MEDLI) suite on MSL entry vehicle heatshield has successfully returned pressure, temperature, and thermal protection system (TPS) ablation data acquired during entry. This paper provides an initial assessment of MEDLI thermal instrumentation data that is comprised of in-depth temperatures in the TPS made of Phenolic-Impregnated Carbon Ablator (PICA). Temperatures are measured in-depth at seven different locations on the surface. The thermal sensor plugs are also characterized in arc jet facilities to quantify measurement uncertainties and biases. The assessment of flight data provides key insights into boundary layer transition to turbulence, surface recession, turbulent heating augmentation, stagnation point and apex laminar heating, and in-depth thermal response. A preliminary comparison with model results highlights inadequacies in our predictive capability. The peak temperature measured by near surface thermocouples was found to be 1049 C in the vicinity of apex region. Initial estimate of peak surface temperature with nominal model settings is about 1575 C. The peak heat flux was found to be on the leeside of the vehicle as predicted, but its value is sensitive to the recession model.