planning roadmaps are developed to pursue NASA’s objectives and as priorities are set among them, decisions be based on the potential for making the greatest impact and that the strategic roadmaps do the following:

  • Emphasize the critical scientific or technical breakthroughs that are possible, and in some cases necessary, and

  • Highlight how a vibrant space program can be achieved by selecting from an array of approaches to realizing potential breakthroughs across the full spectrum of goals embodied in NASA’s mission statement.

As programs are developed to fulfill the objectives and generate results, NASA will have to periodically ask whether they are

  • Altering our basic understanding of the cosmos,

  • Changing our perceptions of our place in the universe, and/or

  • Advancing our future as a space-faring civilization.

There are many examples of significant breakthroughs in the history of NASA. Surely, the Apollo program’s landing of a human on the Moon was revolutionary and transformational. So was the Voyager mission to the outer planets, which revealed new and unanticipated worlds; the Hubble Space Telescope, which observes the wonders of the distant universe; and the Earth Observing System missions, which reveal the fantastic complexity of global-scale environmental connectivities on our home planet. Lesser-known programs have also made dramatic advances, such as the collection of missions that have revealed the complexity of Earth’s magnetosphere or the dynamic behavior of the Sun, the results of which are crucial to successful human habitation of space beyond low Earth orbit.

For both human and robotic programs, the basic standard of achievement and impact is whether a program will lead to a fundamentally different understanding or perspective. For future missions or programs it is imperative to prioritize based on which will provide the greatest return. If a new mission or program is to proceed it must demonstrate the potential for, and likelihood of, a transformative outcome, through a more comprehensive approach, increased measurement resolution and sensitivity, or the opportunity to visit or observe some unique new location. The argument needs to be realistic and compelling because available resources always will limit the number of programs that can be supported.

There will be some science programs that enable human exploration and its transformative results and others that in themselves will transform our understanding of the cosmos. These programs will compete with each other for resources, and it will be difficult to select among them. In this competition it is important to insist that “enabling” science must be truly enabling—that is, necessary to solve a critical problem in the exploration program. Such problem-focused research must be subjected to regular reviews that are as open, rigorous, and selective as those conducted to assess proposals for transformative science (e.g., the decadal surveys). In most cases enabling science is broadly multidisciplinary, which calls for review by groups with expertise in diverse specializationsa requirement necessary not only to ensure an appropriate review but also to guard against the possibility that purely disciplinary reviews will have an inappropriately narrow focus on critical problems. To ensure that the research and the reviews stay focused on the problems that need to be solved, it will be important for representatives of organizations that identified the operational requirements and/or that will have to deliver operational systems to participate in the reviews.

Based on the preceding discussions, the committee recommends the following guiding principles:3


These principles share much in common with those recommended in the National Research Council report Science Management in the Human Exploration of Space (National Academy Press, Washington, D.C., 1997).

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