In this week's episode of Prisoners of Gravity, Commander Rick takes a look at what it's like not to be a prisoner of gravity, asking the questions: What are the biggest challenges of living in space? What are the dangers? And what are the benefits? Commander Rick discusses these questions with science fiction authors Geoffrey A. Landis ("A Walk in the Sun"), Michael Skeet ("Breaking Ball"), Frederik Pohl (Mining The Oort), Ben Bova (Mars), Spider and Jeanne Robinson (Starseed), C.J. Cherryh (Heavy Time), Bruce Sterling (Schismatrix), and Michael Swanwick (Griffin's Egg). Also, Nichelle Nichols (Lt. Uhura on Star Trek) talks about her work for NASA's space shuttle astronaut recruitment programme, and Dr. Roberta Bondar, Canada's first female astronaut, tells Rick about some of the medical problems that occur while living in weightlessness.