For scientists trying to understand what ancient Mars might have been like, the red planet sends some mixed signals.
Water-carved valleys and lakebeds leave little doubt that water once flowed on the surface. But climate models for early Mars suggest average temperatures around the globe stayed well below freezing.
A recent study led by Brown University geologists offers a potential bridge between the “warm and wet” story told by Martian geology and the “cold and icy” past suggested by atmospheric models.
The study shows that it’s plausible, even if Mars was generally frozen over, that peak daily temperatures in summer might sneak above freezing just enough to cause melting at the edges of glaciers. That meltwater, produced in relatively small amounts year after year, could have been enough to carve the features observed on the planet today, the researchers conclude.