Perseverance finds evidence of three water events on Mars
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NASA’s Perseverance rover has found evidence that rocks in Mars’ Jezero Crater interacted with water at least three times, offering new clues about the planet’s watery past.
The findings were published in Communications Earth & Environment.
Scientists had been particularly interested in the region after Mars orbiters detected strong signals of carbonate minerals. They expected to find sedimentary rocks formed from layers of material deposited over time, but Perseverance instead encountered igneous rocks formed from magma that preserved evidence of interaction with water.
The discovery was made in the Margin Unit, a geological area along the shoreline of an ancient lake in Jezero Crater.
On Earth, carbonates often form in shallow water and can preserve evidence of past microbial activity. Perseverance is searching for signs of ancient microbial life while studying Mars’ geology and climate, and is collecting and storing rock and regolith samples for possible future analysis.
Perseverance’s SuperCam instrument analysed more than 185 bedrock targets across the Margin Unit. At higher elevations, it found coarse-grained, olivine-rich rocks that showed little evidence of water interaction. The rocks formed deep underground from slowly cooling magma before being exposed by erosion.
At lower elevations, the rocks had been significantly altered. Olivine grains were fractured and contained silica, while carbonate-filled fractures formed after carbon-dioxide-rich groundwater interacted with the rocks.
Scientists said a second water event may have been associated with the ancient lake in Jezero. Silica found in some rocks provided further evidence of water-related alteration, particularly in areas that were once below the lake’s waterline.
A third, later event involved heated underground water. Mineral veins containing calcium sulphate and fluorite were found in the eastern Margin Unit. Fluorite commonly forms when hot water circulates through volcanic rocks, indicating a later hydrothermal event.
The findings could help scientists reconstruct changes in the climate and habitability of early Mars.