Does Mars have liquid water now? Or has its water been trapped in ice for billions of years? May it now, or at any time in the past, have supported life? It all depends on who you talk to. Radically differing theories on Mars have abounded recently, each based on different evidence. The latest study, as detailed in this Space.com story, suggests that dark streaks visible along canyon and crater walls may be signs of running water currently scouring the surface. The streaks occur in areas that some scientists theorize to have thermal activity under the surface, which could cause salty water to occasionally seep up to the surface due to interactions with molten rock. Perhaps these areas will be candidate landing sites for the upcoming Mars Exploration Rovers, whose primary goal is to find indications of past water activity on Mars.