‘For years, scientists have known that Mars has ice locked away within its rusty exterior. More elusive, though, is figuring out how much of that water is actually sloshing around in liquid form. Now, NASA scientists have found compelling evidence that liquid water—life-giving, gloriously wet H 20—exists on Mars.
We’re not talking gushing rivers or oceans here. These scientists have been investigating “recurring slope lineae,” patches of precipitated salt that appear to dribble down Mars’ steep slopes like tears rolling gently down a cheek. Planetary scientists hypothesized that the streaky formations were products of the flow of water, but they didn’t have concrete, mineralogical evidence for that idea until now, says Lujendra Ojha, a scientist at Georgia Tech who first spotted the lineae back in 2010. In a new Nature Geoscience paper, published online today, Ojha and his colleagues present “smoking gun validation” that it was liquid water flowing on Mars’ surface that formed these tear stains.’