THE OVERALL GOAL OF THIS STUDY IS TO ADVANCE THE MASTEN DESCENT ELEMENT (MDE) CONCEPT FOR SYSTEM REQUIREMENTS REVIEW. THIS WILL BE ACCOMPLISHED BY FOCUSING ON THE OVERALL HLS REQUIREMENTS, INCLUDING THOSE RELATED TO INDIVIDUAL ELEMENT AND INTER-ELEMENT INTERFACE, TO INFORM THE OVERALL MISSION. THE MDE WILL TRANSLATE SYSTEM-LEVEL REQUIREMENTS INTO DETAILED FUNCTIONAL AND PERFORMANCE DESIGN CRITERIA AS WELL AS REFINING COMMON INTERFACES IN THE OVERALL HLS FRAMEWORK. THROUGHOUT THIS PROCESS, THE GOAL IS TO REFINE THE MDE DESIGNS THROUGH FREQUENT TESTING AND VALIDATION TO IMPROVE MANUFACTURABILITY AND DRIVE DOWN SCHEDULE DURATIONS AND COSTS. THE DEVELOPMENT APPROACH WILL IDENTIFY KEY AREAS IN NEED OF TECHNOLOGICAL MATURATION AND EXECUTE ON THE PLAN TO EVOLVE THESE CAPABILITIES. ALL OF THESE EFFORTS SUPPORT NASA'S PLAN FOR LAUNCHING THE FIRST HLS ELEMENT DEMONSTRATION MISSION IN 2024. MASTEN WILL PROVIDE A DESCENT ELEMENT TO INTERFACE WITH AN ASCENT ELEMENT AND ACHIEVE THE OBJECTIVE OF DEMONSTRATING A LUNAR SURFACE LANDING OF A FUTURE HUMAN LANDER FROM THE GATEWAY.