Atmospheric Modeling Challenges and Measurement Requirements for Mars Entry, Descent and Landing

Introduction: Successful aerobraking, aerocapture, and entry, descent, and landing (EDL) at Mars requires knowledge of the nominal atmospheric density as well as mesoscale and local weather conditions. Whether aerobraking at altitudes of the order 100 km, aerocapturing at 30-50 km, or performing an EDL sequence where maximum aerodynamic loads occur near 40 km followed by terminal descent to the surface, latitudinal, seasonal, diurnal atmosphere variations, and in the case of terminal descent and landing, near surface winds must all be considered to determine the nominal flight environments. Currently, uncertainties in the nominal atmospheric density associated with the engineering models 2 used for aerobraking, aerocapture, and EDL mission design across these altitude bands range from 25 to 200%. Furthermore, unmodeled, short temporal and spatial scale variations can have a significant affect on the success of the mission.