Study of Capsule Geometry for Dust Sample Acquisition During Mars Atmospheric Entry

This paper explores an appropriate position for the dust-capturing device on the surface of an aeroflyby capsule traveling at a velocity of 4.4 km/s in the Martian atmosphere at an altitude of 36 km. The equation of motion and the heat-transfer equation for dust particles are solved for particle sizes of 0.5 and 0.1 μm. A thermochemical nonequilibrium flowfield over the vehicle is computed using a prismatic unstructured mesh method. Analysis indicates that placing a dust-capturing device on the leeward frustum edge results in less aerodynamic drag and lower surface heat flux than placing the same device on the windward frustum edge. The lower heat flux exerted on the surface of the dust-capturing device is preferable because the aerogel on the surface of the device is less damaged. The temperature of dust particles of 0.5 μm diameter is elevated to almost the phase-change temperature when the dust-capturing device is on the leeward frustum edge, due to longer flight time in the high-temperature shock layer. The temperature of dust particles reaching the device on the windward frustum edge is well below the phase-change temperature. However, this study could not find any position to capture dust particles of 0.1 μm diameter before reaching the phase-change temperature, regardless of the position of the dust-capturing device.