example, will expand the horizons of our knowledge in profound ways. Human spaceflight also presents a clear opportunity to change our sense of our place in the universe. It surely will be a transformative event to place humans on Mars.

The science conducted through the robotic exploration of space and human spaceflight to the Moon and Mars are synergistic enterprises. Both are worthy of inclusion in a robust space program that serves the aspirations of our civilization, and both enhance U.S. leadership in science and technology. Indeed, human exploration and science are united in their purpose to understand the universe in which we live as well as to improve life here on Earth.

The committee also recognized that major advances in understanding will be required to send humans forth on long-duration spaceflight beyond Earth. For example, we do not know with confidence today how to sustain humans in microgravity and how to protect them from the effects of space radiation for long periods. Nor do we know how sound the scientific basis is for the systems needed to support long-duration human spaceflight and remote operations to reliably put humans into space. The behavior of fluids in microgravity will require special attention; the reliability and predictability of materials exposed for long periods to the conditions of space must be investigated; both the medical and the psychological issues related to humans engaging in long-duration spaceflight need to be better understood; and countermeasures for the effects of exposure to radiation and reduced gravity will have to be developed. These essential tasks pose new engineering and science challenges that require fundamental discoveries through basic research across multiple traditional disciplines.

The appropriate science in a vibrant space program is, therefore, nothing less than that science that will transform our understanding of the universe around us, and will in time transform us into a space-faring civilization that extends the human presence across the solar system.

This viewpoint is captured well in NASA’s mission statement as articulated in its 2003 strategic plan:4

“To understand and protect our home planet,

To explore the universe and search for life,

To inspire the next generation of explorers,

… as only NASA can.”

NASA’s mission has its foundation in the Space Act that created NASA, and in other more recent national policy directives.

The committee believes that this is a bold and appropriate agenda. The opportunities for discovery are vast. They encompass the Earth on which we dwell, the Moon and Mars and other places in the solar system where humans might be able to visit, the broader solar system including the Sun that we probe with robotic spacecraft missions, and the vast universe beyond that is reachable only via telescopes. Indeed, there is an extraordinary richness to the opportunities, although not all can be actively pursued given the resources available.

The issue then is not what to pursue ultimately, but rather what to pursue first, and then how to prioritize what follows. The standard for deciding what science to select can be set by recalling the motivation for pursuing space exploration. We do so to ensure that we will continue to advance our intellectual understanding of the cosmos, including our place in it, and will continue our development as a civilization for which human spaceflight becomes routine and inevitable. The array of choices can include plans for missions and enabling science that will not be achieved for decades or longer, but it also needs to include programs from which major achievements can be expected in the nearer term. What is selected must include the essential enabling science that not only will make long-duration human space exploration possible but also will provide the basis and rationale for future space exploration. The results


NASA, National Aeronautics and Space Administration 2003 Strategic Plan, NP-2003-01-298-HQ, NASA, Washington, D.C., 2003.

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