That "Geno" Cernan was commander of Apollo 17, the final manned moon mission, was a fitting conclusion to a flying career that included two previous stints in space (Gemini 9 and Apollo 10). His frank, earthy memoir of his years at NASA adds another entertaining, informative volume to the burgeoning shelf of books illuminating the inner workings of the space program and the people who made it happen. Coauthor Don Davis, a veteran journalist, helps Cernan craft a colloquial prose style that nicely captures the competitive, macho personality that seemed virtually mandatory for astronauts in the 1960s and '70s.....Detailed accounts of each flight, including technical problems and personal tensions (particularly with Apollo 17 teammate Jack Schmitt, distrusted because he was a scientist, not a test pilot), remind readers that the space program is a human endeavor, with inevitable failures that make the triumphs that much sweeter.....