Check out Mary Roach's delightful book on the less well-considered aspects of prolonged space travel: the biological afterthoughts, if you will. The humor is a constant joy. I can just picture her conversations with NASA PR reps: "Our history is replete with tales of heroism and wonder..." "Yes, but where do you keep the astronauts' poop from the Gemini missions?"

For it happens that, in the most direct illustration of "anal-retentive" ever, NASA has kept all of the poop from its astronauts, in deep freeze at the Marshall Space Flight Center. This, plus everything you might ever enjoy knowing about motion sickness testing, space food composition, high-gee and psychological testing, is here.

Peter, thanks for the recommendation. I'm about a quarter into the book (my library had it). I suspect I will be getting her other ones as well--a great read.