Could permafrost under Martian soil be the key to finding life on the red planet? Chris McKay, a planetary scientist for NASA, thinks there's a good chance we'll see evidence of ancient microbes if we just follow the ice. Podcast produced by David Levin. Interview by Anna Lee Strachan. NOVA is produced by WGBH in Boston. Funding for NOVA is provided by ExxonMobil, David H. Koch, the Howard Hughes Medical Institute, the Corporation for Public Broadcasting, and public television viewers. For more fun science stories, visit our website at pbs.org/nova/mars