Key Directions for Entry, Descent and Landing Research for Crewed Mars Missions

With the announcement of the Vision for Space Exploration in 2004, NASA has b een preparing plans for a crewed mission to Mars in the next few decades. One challenge associated with crewed missions to the Martian surface is the comparatively large mass of planned surface elements which will require an increase of at least an order o f magnitude in the landed mass performance of entry, descent and landing (EDL) vehicles compared to previous successful robotic missions and ones currently planned for the near future. A literature survey shows that parachute technology currently used for Martian EDL is unlikely to be extensible to such large missions. The most robust deceleration technology in this regard seems to be a combination of aerodynamic deceleration provided by the vehicle’s heatshield as well as propulsive deceleration provided by a rocket engine. Much of the work done on EDL vehicles of this class focuses on particular subsystems which makes it difficult to judge the effect of the various design parameters on the overall performance of the EDL system. The work presented in this paper looks at the problem from a system perspective by investigating the effect of individual vehicle and mission design parameters on the overall EDL system landed mass performance, using an in-house EDL trajectory simulation and sensitivity analysis to ol that has been validated with experimental and simulated data for Mars missions. The purpose is to identify key technologies that need to be developed and key aspects of vehicle and mission design that need to be investigated to extend the capability of EDL vehicles for crewed Mars missions. Major insights gleaned from the sensitivity analyses include the need for research into propulsive descent safety requirements to prevent over -conservatism in establishing the propulsive descent initiation (PDI) alti tude since a high PDI altitude can significantly lower EDL vehicle landed mass performance. Another area of research with the potential to provide significant improvements in performance is structural and thermal technology that reduces the aeroshell mass of the vehicle.