NASA seems closer than ever to finding evidence of life on the red planet. In the past year alone, they’ve discovered evidence of flowing water on Mars and proof it once had an Earth-like atmosphere. And these discoveries are just the beginning: NASA continues to analyze data from current missions even as it prepares for new ones. Though Martian life remains hypothetical, scientists have an incredibly clear idea what they’re looking for. (Hint: it’s not little green men.) And, as NASA astrobiologist David Des Marais explains in this video, the search for aliens could end up revealing surprising clues to our own existence.