NASA's Perseverance rover has uncovered evidence of at least three distinct water-related events in ancient Martian rocks, challenging earlier assumptions about the planet's geological history. The findings, published in the journal Communications Earth & Environment, come from the analysis of the "Margin Unit" in Jezero Crater, a region once thought to contain sedimentary rocks formed by a long-gone lake. Instead, the rover discovered igneous rock—formed from cooled magma—offering a detailed record of multiple interactions with water. This research, led by Candice Bedford of Purdue University, adds complexity to our understanding of Mars' past environments. To analyze the rocks, the team used the SuperCam instrument mounted on Perseverance's mast. SuperCam uses a laser to reflect light off rocks up to 21 feet (6.5 meters) away, allowing scientists to determine their mineral composition and chemistry. The rover has analyzed over 185 bedrock targets in the area, revealing a wealth of geological information. The Margin Unit, located along the ancient shoreline of a Martian lake, contains carbonate minerals previously detected by orbiting satellites. However, the new study suggests these carbonates formed through multiple water events rather than a single lake environment. The rock formations in the Margin Unit show distinct layers and textures that indicate different geological processes. At higher elevations, the rock was coarse-grained and crystalline, containing olivine, a mineral typically found in magma-formed rocks. This suggests the rock originated deep underground. Lower down, the olivine grains were fractured, with silica filling the gaps—an indication of water interaction. The first water event involved carbon dioxide-rich groundwater reacting with olivine, forming carbonate ridges in the fractures. A second event may have been linked to the ancient lake in the crater, with some rocks showing signs of silica, which can form when olivine turns into carbonate. A third water event created mineral veins composed of calcium sulfate and fluorite, suggesting the presence of heated underground water. Eleni Ravanis of the University of Hawaii at Manoa noted the presence of silica in rocks below the waterline, a finding that adds to the complexity of the geological history. Bedford emphasized that these results challenge previous hypotheses based on orbital data and suggest a more intricate history of water activity in Jezero Crater and potentially across Mars. This discovery highlights the importance of on-the-ground exploration in uncovering the planet's past.