During reentry of the Orion Crew Module (CM), vehicle attitude control will be performed by firing reaction control system (RCS) thrusters. Due to the large scarf angles of the RCS thrusters and simultaneous firing of multiple thrusters, the simulation of the interaction of the RCS plumes with the oncoming flow has been difficult. The Orion aerothermodynamics database relies heavily on wind tunnel test data to capture the heating effects of thruster plume interactions
with the free stream; however, this data is only valid for the continuum portion of the reentry trajectory. To extend the database to high altitudes during Orion CM reentry, a Direct Simulation Monte Carlo (DSMC) analysis was performed to study the vehicle heating effects resulting from the plume to free stream interaction. The study was performed with the DSMC Analysis Code
using plume inflow boundary conditions obtained from Data Parallel Line Relaxation computational fluid dynamics solutions.