Plaxco is a strong introduction to astrobiology, an undergraduate level textbook that is on the 'science' side of 'popular science'. Defining life as "a self-replicating chemical system capable of evolving such that such that it's offspring might be better suited for survival", Plaxco and Gross launch into a history of life on Earth from the Big Bang, and the prospects for the future discovery of life.

As a chemist, Plaxco is biased towards chemistry as the most important part of the question about life. Starting from the fundamental constants of the universe, he argues that elemental abundance and the energy required for chemical reactions means that life will likely be carbon-based and require liquid water. From that, the chemistry gets rather complex. The Miller-Urey 'primordial sludge' experiments show that amino acids are spontaneously generated from pretty basic elements, but doesn't explain how they can link into self-reproducing chains. There was probably a primitive 'RNA world' which has been entirely erased by the exponentially more potent metabolisms and evolutionary capacities of modern bacteria, archaea, and eukaryotes. The sections on the evolution of metabolism and genetics are a slog of chemistry. The last bit, surveying the potential for life on Mars and gas giant moons is a good run down of contemporary science, although this field advances one probe at a time, and some observations may be substantially updated since then.

The over-all impression is that some kind of micro-biological life is probably quite common. Detecting it, particularly at stellar distances, is another matter entirely.