With a host of spacecraft at Mars or being readied to go there over the next two years, scientists are poised to uncover the planet’s liquid secrets. The big question: Was Mars once warm and wet? Simple to pose, but not easy to answer. While many scientists think Mars may once have harbored vast oceans or lakes, there is no proof beyond some presumed ancient shorelines, sediment deposits, and other highly sketchy data or pictures. The question is important because liquid water is a key ingredient for life as we know it. While evidence is rolling in from two spacecraft currently orbiting Mars, an artist has taken some liberties with some of that data to create a series of renderings showing what Mars might once have looked like.