The Blueberries of Mars TIME

Photographs of Mars shot from orbit show vast plains that resemble ancient sea floors, steep gorges that would dwarf the Grand Canyon and sinuous surface scars that look an awful lot like dry riverbeds. Given all that, why were NASA scientists so excited last week to announce that one of their Mars rovers, having crawled across the planet for five weeks, finally determined that Mars, at some point in its deep past, was indeed “drenched”–to use NASA’s term