“Follow the water” has been the mantra in the search for habitable worlds for a long time. Searching for signs of ancient water was the primary goal of NASA’s Mars Exploration Rover mission. Europa’s suspected subsurface ocean leads some to wonder if it could harbor microbial life. In searching for life beyond our Solar System, there is great interest in “ocean planets” that could have vast surface seas.
Now, researchers suggest that inhabited desert planets – like the fictional Arrakis from the novel Dune, or Tattooine from Star Wars – may be more common! Full disclosure: Coauthor Kevin Zahnle is an old friend, and one of my favorite astrobiologists.