In 1991, Belbruno salvaged the Japanese *Hiten* mission to the Moon using a novel method called a ballistic capture transfer, also known as a WSB (weak stability boundary) transfer. This book, filled with Belbruno's own impressionistic sketches and diagrams, gives the story of how he turned the WSB transfer from a theoretical possibility to a practical method of space travel. The trials and tribulations of the researcher are described in detail. Belbruno contrasts the overriding practical needs of industry (in this case, JPL in Pasadena) to the theoretical considerations of academia, and recounts with good humor the anemic and sometimes negative coverage and reaction to the *Hiten* salvage operation. In short, this book does for mathematics what *The Double Helix* did for biochemistry, without the gossip and diatribe that made *The Double Helix* so controversial.

Traditional space travel relies on the use of Hohmann transfers. First, a spacecraft's engines are fired to send it away from the Earth towards the target body. When the spacecraft arrives near the target body, it is generally moving too quickly to be captured by it, so its engines must be fired a second time to slow it down. Not only does this use expensive fuel (Belbruno quotes a cost of $250,000 a pound to bring anything to the orbit of the Moon), but very precise timing; indeed, several spacecraft have been lost when their engines failed to fire during a crucial few minutes of a months-long mission.

For years, a second possibility existed: the ballistic capture transfer. If we might make use a baseball analogy, the Hohmann orbit is like a pitcher throwing the ball to a catcher. But the pitcher can get the ball to a catcher another way: In principle, it ought to be possible for the pitcher to roll the ball along the ground so that friction slows it to a stop just as it reaches the catcher's mitt. This is the essence of a ballistic capture transfer. At the beginning of his researches, Belbruno's intuition suggested the possibility of a ballistic capture transfer, though some of his colleagues felt they would, at best, be impractical. Belbruno showed that such transfers were not only possible, but practical, and salvaging the 1991 *Hiten* mission was the first implementation of this method. Belbruno goes on to describe how the WSB has implications that range from designing more efficient interplanetary missions, to the formation of the Moon, to the annihilation of life on Earth.

Because it was written for a popular audience, the mathematical content of *Fly Me to the Moon* is limited: there are many diagrams, some numbers, but no equations. At the same time, there is much here of interest to the mathematician, for it answers a question many of us have faced, either from ourselves or our students: what can I do with a degree in mathematics? Belbruno ran the gamut from academic to consultant to entrepreneur. Overall, this book is a superb introduction to the life of a real mathematician, and a gentle introduction to some very complex mathematics.

Jeff Suzuki is an Associate Professor of Mathematics at Brooklyn College. His publications include *A History of Mathematics* (Prentice-Hall, 2002) and "The Lost Calculus (1637-1670): Tangency and Optimization Without Limits" (*Mathematics Magazine*, December 2005). His current interests include the mathematics of the eighteenth century, particularly the work of Lagrange, and geometric constructibility.