The proposed design tool will enable the Human Exploration and Operations Mission Directorate's (HEOMD) chartered responsibilities of 1) conducting technology development and demonstrations to reduce costs of future human space flight and 2) enabling U.S. commercial human spaceflight capabilities, by providing a tool that will reduce the cost and time required for design and analysis of spacecraft thermal control systems (TCS). The proposed technology will also benefit unmanned NASA missions requiring TCS design. The National Research Council (NRC) Aeronautics and Space Engineering Board identified top technical challenges and highest priority technologies across all 14 NASA space technology roadmaps. Based on the items identified in the study, thermal control systems are a key, enabling technology that contributes to the advancement of many of the top technical challenges and the highest priority technologies. The proposed reduced-order thermal design tool will be able to contribute to overcoming the obstacles of these technical challenges. Similarly to NASA unmanned missions, this proposed design tool will be of interest to other Government spacecraft procuring agencies such as the Air Force, Navy, National Reconnaissance Office, and Operationally Responsive Space Office, as well as, prime contractor spacecraft developers such as ATK, Lockheed Martin, Boeing, Northrop Grumman, Sierra Nevada Corporation, and Raytheon. LoadPath will continually engage with potential Government and commercial end users during the Phase I and Phase II efforts to ensure their needs are considered during the design tool development.