Signs of Ancient Water

Orbital images reveal ancient river deltas, lakebeds, and mineral deposits that only form in the presence of water. The Curiosity rover found rounded pebbles in Gale Crater — smoothed by flowing water billions of years ago. Perseverance rover is currently exploring Jezero Crater, an ancient lake that once had a river feeding into it.

Finding past water matters because on Earth, wherever there is liquid water, there is life. Mars held water for hundreds of millions of years — potentially long enough for microbial life to gain a foothold. That is why so many missions are built around the search for it.