Overview of the NASA Entry, Descent and Landing Systems Analysis Exploration Feed-Forward Study

NASA senior management commissioned the Entry, Descent and Landing Systems Analysis (EDL-SA) Study in 2008 to identify and roadmap the Entry, Descent and Landing (EDL) technology investments that the agency needed to successfully land large payloads at Mars for both robotic and human-scale missions. Year 1 of the study focused on technologies required for Exploration-class missions to land payloads of 20 to 50 t. Inflatable decelerators, rigid aeroshell and supersonic retro-propulsion emerged as the top candidate technologies. In Year 2 of the study, low TRL technologies identified in Year 1, inflatable aeroshells and supersonic retropropulsion, were combined to create a demonstration precursor robotic mission. This part of the EDL-SA Year 2 effort, called Exploration Feed Forward (EFF), took much of the systems analysis simulation and component model development from Year 1 to the next level of detail. A main objective of the study was to determine the maximum payload mass (to Mars touchdown) capability of a Delta IV-H launch vehicle, given the spacecraft launch mass constraint of 7.2 t and assuming the 2024 Mars opportunity. The simulation results, using the latest component mass models, indicated that a direct entry system could deliver approximately 3.5 t to 0 km above the Mars Orbiter Laser Altimeter (MOLA) areoid. A second objective was to characterize the performance required of the supersonic retro-propulsion system. The study, which assumed four engines with a specific impulse of 338s and a system thrust-to-weight of 3.7 Mars g’s, yielded descent engine initiation between Mach 1.4 and 1.8 at an altitude between 3 and 8 km. A third major objective was to use the high fidelity entry simulation to characterize an Autonomous Landing and Hazard Avoidance Technology (ALHAT) like sensor suite for Mars. Initial performance range results were obtained for terrain relative navigation, hazard detection and avoidance, velocimeter and altimeter sensor systems. This paper summarizes the analysis performed to meet the EFF objectives, the study results and recommendations for future investment.