Heatshield erosion in a dusty Martian atmosphere

The effects of dust particle impacts on the erosion of the forebody heatshield were calculated for a 26 m diameter aerobraking vehicle entering a dusty Martian atmosphere at 8600 m/s. An explicit, thin-layer, Navier-Stokes code was used to compute the dustless flowfield about the vehicle for the actual Martian atmospheric composition. The deceleration and melting of 1-19 mu m diameter dust particles within the forebody shock layer were computed. All particles began vaporizing shortly after entering the shock layer, but most survived to hit the heatshield surface. The two different heatshield materials considered were Shuttle ceramic tiles and the ablator used on the Apollo capsule. For a vehicle with a ballistic coefficient of 200 kg/m super(2), the heatshield surfaces experienced an average of about 7 mm of surface erosion. For the ablator, the increase in the forebody thermal protection mass was 29%, or about 1.3% of the vehicle's mass. This modest mass penalty does not compromise the use of aerobraking at Mars.