Thruster Plume Surface Interactions: Applications for Spacecraft Landings on Planetary Bodies

Abstract

Numerical and experimental investigations of supersonic jet interactions with a flat surface at various atmospheric pressures are presented in this paper. These studies were done in assessing the landing hazards of both the NASA Mars Science Laboratory and the Phoenix Mars spacecraft. Temporal and spatial ground pressure measurements in conjunction with numerical solutions at altitudes of nozzle exit diameters and jet expansion ratios between 0.02 and 100 are used. This study shows that, for typical landing spacecraft engine parameters, thruster plumes exhausting into Martian environments create the largest surface pressure loads and can occur at high spacecraft altitudes in contrast to the jet interactions, which occur in terrestrial and lunar atmospheres. These differences are dependent on the stability and dynamics of the plate shock, the length of the supersonic core, and plume decay due to shear layer instability, all of which are functions of the jet expansion ratio. Theoretical, experimental, and analytical results show that subscale supersonic cold gas jets adequately simulate the flowfield and loads due to rocket plume impingement, provided important scaling parameters are in agreement. These studies indicate the critical importance of testing and modeling plume–surface interactions for descent and ascent of spacecraft and launch vehicles.