Following the suggestion of my friend Neil Laferty, I purchased Neil deGrasse Tyson’s Space Chronicles: Facing the Ultimate Frontier.
The book is a collection of speeches, interviews, essays, etc. on various aspects of space exploration: why we did it, why we should keep doing it, what problems we have doing it, and the like. It reads well – Tyson never uses science jargon as a way of keeping the hoi polloi at the gates, and even a non-scientist like me could understand the concepts. He looks at all the arguments with a sympathetic eye, while simultaneously maintaining a healthy scientific skepticism. This is no mean feat, and he nails it.
Make sure you read the appendices, which include the legislation creating NASA and other bits of space-related legislation as well as budget comparisons and data for space exploration.