Guided Entry Performance of Low Ballistic Coefficient Vehicles at Mars

Current Mars entry, descent, and landing technology is near its performance limit and may be unable to land payloads on the surface that exceed 1 metric ton. One option for increasing landed payload mass capability is decreasing the entry vehicle's hypersonic ballistic coefficient. A lower ballistic coefficient vehicle decelerates higher in the atmosphere, providing the additional timeline and altitude margin necessary to land more massive payloads. This study analyzed the guided entry performance of several low ballistic coefficient vehicle concepts on Mars. A terminal point controller guidance algorithm, based on the Apollo Final Phase algorithm, was used to provide precision targeting capability. Terminal accuracy, peak deceleration, peak heat rate, and integrated heat load were assessed and compared with a traditional Mars entry vehicle concept to determine the effects of lowering the vehicle ballistic coefficient on entry performance. Results indicate that, while terminal accuracy degrades slightly with decreasing ballistic coefficient, terminal accuracy rivals the performance of current entry systems for ballistic coefficients as low as 1 kg/m(2). These results demonstrate that guided entry vehicles with low ballistic coefficients (large diameters) may be feasible on Mars. Additionally, the flight performance determined by this investigation may be improved through the use of new guidance schemes designed specifically for low ballistic coefficient vehicles, as well as novel terminal descent systems designed around low ballistic coefficient trajectories.