West is where the riverbeds, the deltas, the sites of ancient gushing water once were. In July, 2024, after covering 18 miles in nearly three and a half years, it arrived at a quarter-mile-wide river valley that is home to a 3.2-ft.-long rock NASA scientists have dubbed Cheyava Falls—and there it hit paydirt. As a new paper in Nature reports, a sample Perseverance drilled from the rock may contain potential biosignatures of long ago microbial life.