Book excerpt: Though more than forty years old, the space age has just begun, and questions about its future abound. What will replace the Space Shuttle? Will the International Space Station justify its $100 billion potential cost? Are asteroids real threats to Earth or just the subject of science fiction movies? Will humans land on Mars? Will the search for extraterrestrial life be rewarded? In Space Policy in the Twenty-First Century, W. Henry Lambright brings together ten top-ranking observers of United States space exploration to address these and other issues relating to the future of the space program. While the U.S. no longer competes with the Soviets for technological "firsts," they argue, ideology and national image remain at the core of space policy, with other factors playing subordinate roles. Reminding readers of the historical highlights, the authors pose searching questions about the priorities and applications of space science, manned vs. unmanned flights, and commercial access to the space enterprise. Contributors include: Christopher F. Chyba, SETI Institute and Stanford University; Ronald J. Deibert, University of Toronto; Daniel H. Deudney, the Johns Hopkins University; W. Henry Lambright, Syracuse University; Roger D. Launius, NASA; Karl A. Leib, Syracuse University; John M. Logsdon, George Washington University; Howard E. McCurdy, American University; Scott N. Pace, White House Office of Science and Technology Policy; and Debora L. VanNijnatten, Wilfrid Laurier University.