Loss of taste for most foods, vision problems, loss of muscle mass and bone density. In light of these and the many unpleasant our outright dangerous effects of space travel on human physiology, science writer and cartoonist Zach Weinersmith wonders: When it comes to the dream of space expansion, what exactly do we hope to gain? Listen as he and EconTalk's Russ Roberts discuss his new book (co-authored with Kelly Weinersmith) A City on Mars, which offers a hard-nosed yet humorous look at the sobering and lesser-discussed challenges involved in building space settlements. Topics include the particular problems posed by the moon and Mars's atmospheres; the potential difficulty of reproducing in zero gravity; and the dangerous tendency to overlook a key factor in whether space settlement is a good idea: the fact that people are people, wherever they may be.