NASA's Perseverance rover has discovered complex igneous rock formations in the Margin Unit of Jezero Crater on Mars. Contrary to initial expectations of sedimentary deposits, the rover identified rocks that show evidence of interacting with water on at least three distinct occasions, altering their chemical composition and appearance.
The findings were obtained using the SuperCam instrument, which analyzes mineralogy by firing a laser at targets up to 6.5 meters away. The rover has examined over 185 bedrock targets across the area, which spans approximately 265 meters in elevation. The data suggests the site served as a crossroads for multiple aqueous systems.
Analysis revealed that early water interactions involved carbon-dioxide-rich groundwater reacting with olivine to form carbonate ridges. Subsequent events included interactions with the ancient lake and a later episode involving heated water, which deposited minerals such as calcium sulfate and fluorite in veins up to 25 centimeters thick.
These results, published in the journal Communications Earth & Environment, challenge previous hypotheses derived from orbital observations. The presence of carbonate and silica minerals is significant for astrobiology, as such environments on Earth can support microbial life by providing hydrogen and preserving biological traces.
