Could Mars Have a Cold, Icy Past?

Scientists have speculated that the channels and valleys of the Martian surface were carved by flowing water during the planet’s “wet and warm” years. In a study recently published in the Journal of Geophysical Research – Planets, however, researchers say that the water needed to carve these features may have accumulated as snow and ice first. Geologist Laura Kerber, a co-author on the study, describes how the Red Planet’s geology presents a case for a “cold and icy” ancient climate on Mars.

*The copy above was updated on June 19, 2015, to reflect the following change: An earlier version stated that, reporting in a recent study, researchers said that channels and valleys on the Martian surface may have been carved by ice. In fact, they reported that the features may have been carved by water that might have accumulated first as snow and ice.