Book excerpt: Historically, the United States has been a world leader in aerospace endeavors in both the government and commercial sectors. A key factor in aerospace leadership is continuous development of advanced technology, which is critical to U.S. ambitions in space, including a human mission to Mars. To continue to achieve progress, NASA is currently executing a series of aeronautics and space technology programs using a roadmapping process to identify technology needs and improve the management of its technology development portfolio. NASA created a set of 14 draft technology roadmaps in 2010 to guide the development of space technologies. In 2015, NASA issued a revised set of roadmaps. A significant new aspect of the update has been the effort to assess the relevance of the technologies by listing the enabling and enhancing technologies for specific design reference missions (DRMs) from the Human Exploration and Operations Mission Directorate and the Science Mission Directorate. NASA Space Technology Roadmaps and Priorities Revisited prioritizes new technologies in the 2015 roadmaps and recommends a methodology for conducting independent reviews of future updates to NASA's space technology roadmaps, which are expected to occur every 4 years.