Podcast host Steve Mirsky talks with author Mary Roach about her new book "Packing For Mars: The Curious Science of Life in the Void." Part 2 of 2. (Part 1 is at http://www.scientificamerican.com/podcast/episode.cfm?id=mary-roach-is-packing-for-mars-10-08-20). Web sites related to content of this podcast include www.maryroach.net.