Astrobiology has finally become a serious discipline, and this book provides an engaging way to get a read on the critical research questions and on where things stand today (although "today" recedes awfully quickly in this field).
Chris Impey interviews a collection of scientists and others working as researchers or speculators on topics central to astrobiology -- how life originated on earth, how likely it is to develop in other environments, how likely it is that life elsewhere would evolve intelligence, how many planets and moons might provide suitable environments, how we might detect life elsewhere, how different that life might be from what we know, and how good a position we are in to answer any of these questions.
You might think that a book composed of interviews -- dialogs between Impey and his subjects, each about 10 to 15 pages long -- would be a relatively breezy read. But it isn't. So many scientific disciplines are involved, and so many difficult and complex questions are crucial to astrobiological research that no reader could be prepared for everything that Impey and his subjects delve into. In my own case, I have a much stronger background in astronomy than in so many of the topics that appear earlier in the book -- geology, paleontology, biology, . . . I slogged through some of those earlier discussions more slowly, occasionally hitting other sources to fill in the background for some of the discussions.
I enjoyed reading the book -- it gave me just what I was looking for in terms of an understanding of where the field is today. On the whole, with some exceptions, the subjects of Impey's interviews are optimistic about finding life, if not intelligent life, elsewhere, even within our own solar system (Mars, Europa, and Titan being the most intriguing candidates).
I don't think Impey is obligated to provide a "balanced" view -- after all, astrobiology and the search for extraterrestrial life, as careers, will likely draw more optimists than pessimists. If you want more pessimistic views, there's plenty to read out there, including especially Ward and Brownlee's "Rare Earth" referenced frequently in this book.
What this book gives us is that state of the discipline report, with personal perspectives from some of its leading figures.