Nasa thought an ancient Martian lake shaped these rocks; Perseverance found evidence of three water events

When Nasa’s Perseverance rover reached the inner edge of Jezero Crater in September 2023, scientists expected to find sedimentary rocks shaped by an ancient Martian lake. Instead, the rover discovered igneous rocks whose minerals preserve a much more complicated history of water activity. A new study published in Communications Earth & Environment shows that the rocks in an area known as the Margin Unit interacted with water during at least three separate episodes. The evidence points to carbon dioxide-rich groundwater, later interaction with the ancient Jezero lake or changing groundwater conditions, and finally a hotter hydrothermal event that left mineral veins behind.