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A bleached white rock on Mars. On Earth, rocks like this would only form over millions of years under warm and moist conditions. |Image source: NASA
A new study of unusually bleached rocks suggests that Mars was once home to wet regions with heavy rainfall, similar to tropical regions on Earth.
Researchers are intrigued by strange, light-colored rocks discovered by NASA’s Perseverance rover on the surface of Mars. Upon closer inspection, the rocks turned out to be kaolinite, an aluminum-rich clay, the scientists said in a study published in the journal Dec. 1. Communications Earth & Environment.
On Earth, kaolinite almost always forms under very warm, moist conditions, such as those found in tropical rainforests. It usually forms in rocks that have been stripped of all other minerals by regular rainfall over millions of years. But nowadays Mars It is notoriously cold and dry.
“So when you see kaolinite in a place like Mars, which is barren, cold, and certainly has no liquid water on the surface, that tells us that there was once a lot more water than there is now,” Adrian BrozSoil scientists at Purdue University and lead author of the study said in a report statement.
Broz and his team compared the structure of Martian kaolinite, which was examined with various instruments on board Perseverance, to terrestrial samples taken from South Africa and San Diego. The rocks look strikingly similar, suggesting they were formed in similar ways.
Satellite image of the surface of Mars Elsewhere on Earth appears to show larger kaolinite deposits. However, Perseverance and other rovers have yet to explore these areas.
Three satellite images (A – C) of the possible presence of the mineral kaolin in the Jezero Crater area. This image shows the reflectance spectra of Martian rocks and kaolinite on Earth (D). |Image source: NASA/Communications Earth and Environment
“Until we can actually reach these large outcrops with rovers, these small rocks are our only ground-based evidence,” Briony Hogana planetary scientist at Purdue University and co-author of the study said in a statement.
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The presence of kaolinite on Mars strengthens the following hypothesis: The Red Planet is a humid oasis At some point in the distant past, although exactly when and how it dried up is still debated.
The main hypothesis states The planet lost its water Sometime between 3 billion and 4 billion years ago, its magnetic field weakened enough to allow solar wind to strip away its atmosphere. But the process can be complex and multifaceted. Studying these ancient clays could give scientists a deeper understanding of how and when Mars lost water, the researchers said.
Broz said it could also provide clues about Mars’ potential habitability because “All life needs water“.
