Aerothermal heating predictions for Mars Microprobe

A combination of computational predictions and experimental measurements of the aerothermal heating expected on the two Mars Microprobes during their entry to Mars is presented. The maximum,nonablating heating rate at the veh icle's stagnation point (at zero angle of attack) is predicted for an under shoot trajectory to be 194 W/cm(2) with associated stagnation-point pressur e of 0.064 atm. Maximum stagnation-point pressure occurs later during the u ndershoot trajectory and is 0.094 atm. From computations at seven overshoot -trajectory points, the maximum heat load expected at the stagnation point is near 8800 J/cm(2). Heat rates and heat loads on the vehicle's afterbody are much lower than on the forebody. At 0-deg angle of attack, heating over much of the hemispherical afterbody is predicted to be less than 2% of the stagnation-point value. Good qualitative agreement is demonstrated for for ebody and afterbody heating between computational fluid dynamics calculatio ns at Mars entry conditions and experimental thermographic phosphor measure ments from the NASA Langley Research Center 20-Inch Mach 6 Air Tunnel. A no vel approach that incorporates six-degree-of-freedom trajectory simulations to perform a statistical estimate of the effect of angle of attack and oth er off-nominal conditions on heating is included.