In order to improve landing accuracies on Mars in preparation for future manned mission, effort has been made in improving control of the vehicle through the use of reaction control system jets under rarefied conditions where normal control surfaces (ailerons, rudders, etc.) are ineffective. Despite their use on Apollo and Viking landers, as well as the space shuttle, firing the reaction control system (RCS) jets can have unanticipated effects on the aeroshell such as augmented heating and induced adverse forces and moments. In order to better understand the aerodynamics of the interactions of reaction control system jets with the aerodynamics of the spacecraft aeroshell in highspeed flow, a qualitative and quantitative study using an experimental method termed Planar Laser Induced Iodine Fluorescence was conducted.