Despite the political imperatives which have caused America's civil space programme to direct most of its budget towards human spaceflight, there is no doubt that the creation of the national Aeronautics and Space Administration has also inspired a global revolution in scientific knowledge. For more than four decades, NASA has pioneered the exploration of the 'Final Frontier', opening a window on the Universe that has transformed our vision of the planets, stars, and galaxies.   As befits an agency created with a remit to inform and inspire the American people, much of this endeavor--the triumphs and the tragedies--has been pursued in the full glare of global publicity. However, despite such remarkable openness, NASA's history has inevitably included less-publicized episodes of controversy and dissension. Reports and memoranda written by some of the key participants in these political and managerial battles--many published for the first time--stand out as the gems in this fascinating collection of more than 120 documents recounting the history and development of the US space-science programme.   These snapshots, recalling some of the most significant moments in the chequered past of NASA's space-science enterprise, are organized into three sections. The first chapter is devoted to the origins and early organization of US space science, beginning with the programme to explore the ionosphere and the response to the launch of Sputnik I. The remaining chapters cover NASA's solar-system exploration efforts and the evolution of space-based astronomy and astrophysics. Particularly fascinating are the documents from the 1980s that detail the desperate struggles by NASA's leaders to maintain a programme of solar-system exploration at a time when the agency's budget was being slashed and political support was waning. Among them is a proposal from NASA administrator James Beggs to terminate the entire planetary programme, thereby making JPL surplus to NASA's needs. Another revelation is an illustrated 'comic book', produced in 1984 by George Field of the national Research Council, to explain to government accountants and politicians the necessity of pursuing all four of NASA's proposed 'great observatories'.