Great to see that online!

I strongly recommend his "To a Rocky Moon", and not only because we went to the same small college.

To A Rocky Moon (University of Arizona, 1994) is probably the best single space exploration and science book I've read. Wilhelms manages to convey a ton of scientific detail, provide a lot of fascinating "behind the scenes" detail on the decisionmaking that went into Apollo and how the scientific process (and scientific politics!) really works, and he gives some great portraits of the personalities invovled -- Wilhems is a very humanistic sort of writer. Really fascinating stuff.

It's probably not the best first book for someone who knows nothing about geology, or who at least doesn't have some good general science knowledge, but neither do you need advanced study. There's definitely no math. Given how much detail Wilhelm goes into I think he does about as good as possible to make it accessible; I don't think anyone who is interested enough to read this board would have a problem.