For the first time, scientists have mapped vast, continent-scale river drainage systems on Mars — ancient networks that may also be among the most promising places to search for signs of past life.
Billions of years ago, before the Red Planet became the frigid desert it is today, water sculpted its surface on a massive scale. For decades, Mars has tempted scientists with whispered clues of that watery past, long-dry rivers that carved valleys and spilled through crater rims into deep canyons, hinting at a world that once looked far more like Earth. But although scientists had cataloged thousands of these ancient waterways, they didn't know how they fit together, or whether Mars once hosted large, integrated river systems similar to those that support some of Earth's most biodiverse environments.
