Mars was once home to wet, humid areas that received heavy rainfall, similar to tropical regions on Earth, a new study of unusually bleached rocks suggests.
Researchers were intrigued by peculiar light-colored rocks that NASA‘s Perseverance rover discovered on the Martian surface. Upon closer inspection, the rocks turned out to be kaolinite, an aluminum-rich type of clay, the scientists reported in the study, which was published Dec. 1 in the journal Communications Earth & Environment.
“Until we can actually get to these large outcroppings with the rover, these small rocks are our only on-the-ground evidence,” Briony Horgan, a planetary scientist at Purdue University and co-author of the study, said in the statement.
The presence of kaolinite on Mars adds weight to the hypothesis that the Red Planet was a wet oasis at some point in the distant past, though exactly when and how it dried up are still debated.
The leading hypotheses suggest that the planet lost its water sometime between 3 billion and 4 billion years ago, when its magnetic field weakened enough for solar winds to strip away its atmosphere. But this process was likely complex and multifaceted. Studying these ancient clays could give scientists more insight into how and when Mars lost its water, the researchers said.
It could also provide clues about Mars’ potential habitability, Broz said, since “all life uses water.”