Mars is littered with valley networks, deltas and lake deposits, meaning it must have had freely flowing water at some point, probably around 4 billion years ago. But climate models of the planet’s deep past haven’t been able to produce warm enough conditions to allow liquid water on the surface.
“There are people trying to model Mars’ ancient climate using the same kind of models we use here on Earth, and they’re having a really hard time doing it. It’s difficult to create a warm ancient Mars because the sun was a lot fainter then. The whole solar system was cooler,” said Briony Horgan, an assistant professor of earth, atmospheric and planetary sciences at Purdue University. “While a lot of people are using climate models, we’re coming at this from a unique perspective – what does the volcanic record of Mars tell us?” [More at links]