A timely if often tedious assessment of where the US space program has been, how it got there, and where NASA scientists hope it will go in the next 50 years, by the author of From Vinland to Mars (1976), The Voyages of Apollo (1974), etc. Deciding on the next step in space exploration isn't difficult, Lewis maintains; neither is developing the technology to achieve it. In fact, a step-by-step plan for expanding the US presence in space, concluding with a manned mission to Mars, was presented by NASA's Space Task Group in 1969 and has remained essentially unchanged ever since. But a 15-year derailment due to problems with the Shuttle, indecision on the part of NASA officials, and, particularly, funding fluctuations as dictated by Congress have proved that scientific vision and technological feasibility are not enough. Pioneering the heavens requires steady, long-range government commitment, both philosophical and financial, over the span of several administrations. Lewis hammers this message home with his review of NASA's designs for the upcoming low-earth-orbit space station, which have been characteristically altered and re-altered to satisfy both a sporadically reduced budget and Congress' unpredictable demands while the actual building of the station is repeatedly postponed. The frustrating story repeats itself in the development of a Moon station, despite recent evidence of a potentially valuable energy source there (Helium 3), and in the exploration of Mars. In the absence of the Apollo missions' spirit of Cold War competition, a growing grass-roots movement supporting international coexploration of space and/or an increasing sense of America's pioneering tradition might provide sufficient motivation for an effective space program, suggests Lewis. But without a durable, wide-ranging vision, all NASA's spaceship designs and exploration schedules are, no matter how elegant, essentially useless. A valuable historical sourcebook, if oddly passionless in style.