Impact of MPF Aeroshell Configuration on Static Instability at Small Angle of Attack

It is found Mars Pathfinder (MPF) experienced static instabilities along the trajectory when entering Martian atmosphere at 2 degrees’ angle of attack. The reason for the instability and the impact of the configuration of the sphere-cone probe shape have been investigated. Three-dimensional Navier-Stokes equations have been solved, where high temperature gas effects were considered by employing the chemical reaction models. The results of aerodynamic characteristics were compared with LAURA, which showed a good agreement. The distribution of the subsonic area at different trajectory point exhibits direct connection with the static instability. The sonic line movement leading to the pressure variation on the surface causes the instability. Different aeroshell configurations with various half cone angle have been simulated. The results show that the distribution of the subsonic zone changes as the aeroshell shape varies and the static instabilities are reduced. The static instability can be controlled by simply change the aeroshell configuration.