The United States stands at the threshold of a new era of human spaceflight. In its first term, the new administration will make the most important decisions in a generation about this endeavor. What are those decisions, and how should they be made in the best interests of the country? • When should the United States retire the Space Shuttle? • How should the nation utilize the International Space Station? • Should the United States return to the moon? If so, how and on what schedule? • How should future plans balance the moon, Mars, and other possible destinations? Ultimately, these decisions derive from the larger question: Why fly people into space? To answer these questions we rethink the rationales for government-funded human spaceflight and then address current policy questions in light of those rationales.