Most observers would point to the 1969 Apollo moon landing as the single greatest accomplishment of NASA, yet prominent scientists, engineers, and public officials were questioning the purpose of the U.S. space program, even at the height of its national popularity. Defining NASA looks at the turbulent history of the space agency and the political controversies behind its funding. W. D. Kay examines the agency's activities and behavior by taking into account not only the political climate, but also the changes in how public officials conceptualize space policy. He explores what policymakers envisioned when they created the agency in 1958, why support for the Apollo program was so strong in the 1960s only to fade away in such a relatively short period of time, what caused NASA and the space program to languish throughout most of the 1970s only to reemerge in the 1980s, and, finally, what role the agency plays today.