DSMC Aero-Thermo-Dynamic Analysis of a Sample-Return Capsule

Future exploration programs, promoted by the main world space agencies, deal with sample return missions to planets like Mars or to asteroids and comets. In this study, an aero-thermo-dynamic analysis of a possible Earth Return Capsule during the high energy, high altitude re-entry path from an exploration mission is presented. The altitude interval 70-120 km is considered, where the capsule experiences different flow fields. In fact, rarefaction ranges from the continuum low density regime to the near free molecular flow and, even though the free stream velocity has been considered constant (13 km/s) in the whole altitude interval, the Mach number changes from 44 to 32 and the Reynolds number, based on the capsule diameter, ranges from 4.92???104 to 9. The computations were carried out using two direct simulation Monte Carlo codes: the 2-D code DS2V to compute local quantities such as heat flux, thermal and aerodynamic loads at zero angle of attack and the 3-D code DS3V to compute global aerodynamic coefficients in the range of the angle of attack 0-60 deg.. The results verified that in this altitude interval the heat flux and the thermal load satisfy reasonably the requirements for the thermal protection system and that the capsule is longitudinally stable up to an angle of attack of about 40 deg..