T he space program no longer lights up our national imagination, as it did in the days when our goal was to be the first country to make it to the moon. Perhaps Mary Roach's new book, Packing for Mars: The Curious Science of Life in the Void , will reignite some interest. But rather than focusing on the sublime aspects of space travel, Roach, the author of Stiffed and Bonk , reports from various training and research facilities on more mundane matters: How are astronauts selected? What if they have to relieve themselves, or vomit? What happens to personal hygiene inside a spacesuit for two weeks? Can you have sex in space? The answers turn out to be fascinating (the upchuck dilemma, it seems, nearly derailed the Apollo 11 mission to the moon), and Roach's prose manages to be both charming and informative, full of funny asides. (One scientist "has a minor in explosives and the personality of someone who shouldn't.") A book ostensibly about space, it turns out, teaches just as much about life on earth.