NASA's Perseverance finds complex record of water activity on early Mars
Rocks in Jezero Crater's Margin Unit show water interacted with them on at least three separate occasions, a new study in Communications Earth & Environment reports.
NASA’s Perseverance rover has found that rocks along the shoreline of an ancient Martian lake record water flowing across early Mars on at least three separate occasions, the agency announced on Monday.
When Perseverance reached the inner edge of Jezero Crater in September 2023, scientists expected to find sedimentary rocks in the area, known as the “Margin Unit”, because it stretches along the shoreline of an ancient lake. Instead they found igneous rock — and those rocks preserved an “astonishingly complex record of water activity”, with each encounter further altering their chemistry and appearance.
The findings, published in the journal Communications Earth & Environment, came from the SuperCam instrument on the rover’s mast, which identifies a rock’s minerals from the light it reflects and can fire its laser up to 21 feet (6.5 metres) away. Perseverance has analysed more than 185 bedrock targets this way.
The team can sequence the water interactions but not their age: first, carbon-dioxide-rich groundwater reacted with olivine, leaving carbonate-filled fractures in the low-elevation bedrock; a second episode may be linked to the crater’s lake; and finally, a heated underground-water event produced mineral veins — including fluorite, which typically forms when hot water circulates through volcanic rock — about 10 inches (25 centimetres) thick in the unit’s east.
“This location became a sort of crossroads for aqueous systems,” said Candice Bedford, a research scientist at Purdue University and the study’s lead author.
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