Almost every proposed lunar mission architecture includes the use of what the space industry calls “ISRU”: in situ resource utilization. Put simply, it means to take the material resources available off-world and put them to industrial use. LEGACY is a space program to design, develop, test, and ultimately demonstrate the use of equipment that enables ISRU on the lunar surface. In the spirit of the heyday of human spaceflight, LEGACY lays out the process for the world to progressively develop the essential capability for lunar ISRU using Space Decentral.