Bright white rocks spotted by NASA’s Perseverance rover are rewriting what we thought we knew about ancient Mars. These aluminum-rich clays, called kaolinite, usually form on Earth only after millions of years of heavy rainfall in warm, humid environments—conditions similar to tropical rainforests. Their presence on today’s cold, dry Mars suggests the planet once had abundant rain, flowing water, and possibly lush oases long ago. Even more puzzling, the rocks are scattered across the landscape with no obvious source nearby, hinting at dramatic ancient events like floods, river transport, or asteroid impacts.
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