Co-Optimization of Mid Lift to Drag Vehicle Concepts for Mars Atmospheric Entry

Abstract

As NASA continues to make plans for future robotic precursor and eventual human missions to Mars, the need to characterize and develop designs for entry vehicles capable of delivering large masses to the surface of Mars will persist. In combination with this, NASA has recognized that the current heritage technology for Mars’ Entry Decent and Landing (EDL) does not have the capability to land the required payload masses. Both the Thermal Protection System (TPS) and the Descent/Landing systems require new design approaches. Because of these needs, NASA has performed an Entry, Descent and Landing Systems Analysis (EDL-SA) study for high mass exploration and science missions to identify key enabling technology areas for further investment. One key technology area identified includes rigid aeroshell shapes for aerodynamic performance and controllability. In this investigation, a system optimization study of alternative aeroshell shapes for Mars exploration class payloads of approximately 40 metric tons has been conducted. This system optimization is accomplished using a Multi-disciplinary Design Optimization (MDO) framework which accounts for the aeroshell shape, trajectory, thermal protection system, and vehicle subsystem closure along with a Multi Objective Genetic Algorithm (MOGA) for the initial shape exploration. This is accomplished using a combination of engineering analysis and higher-fidelity physics based tools along with optimization methods and engineering judgment. The results of this process have shown that a proposed family of optimized mid lift-to-drag aeroshell shapes exhibit a significant improvement to the current reference entry rigid aeroshell configuration. Furthermore, a trade-off between the vehicle TPS and structural mass is identified for this class of aeroshell shapes and their corresponding trajectories. Balancing this trade-off can yield an overall decrease in the total vehicle mass or corresponding increase in landed payload, as compared to the current reference configuration.