A bleached white rock on Mars. On Earth, rocks like these only form after millions of years of hot, humid conditions.
Strangely discolored clay rocks discovered on Mars by the Perseverance rover suggest the Red Planet was once a tropical oasis.
A new analysis, published in a study last week in Communications Earth & Environmentrevealed that Mars was once home to humid areas that had intense rainfall, similar to tropical regions on Earth.
The theory began to formulate when NASA’s Perseverance rover found peculiar light-colored rocks on the Martian surface. The rocks later revealed to be caulinitea type of clay rich in aluminum.
On Earth, kaolinite almost always forms under very hot and humid conditions, such as those found in tropical forests. It typically forms in rocks that have been stripped of all other minerals by millions of years of regular rain.
However, present-day Mars is notoriously cold and dry. “So when you see kaolinite in a place like Mars, where it is sterile, cold and certainly without liquid water on the surface, that tells us that There was once much more water than there is today”, he explained, in , Adrian Brozsoil scientist at Purdue University and lead author of the study.
As detailed by , the team compared the structure of Martian kaolinite with terrestrial samples taken from South Africa and San Diego (USA). The rocks looked surprisingly similar – suggesting they formed in similar ways.
Satellite images of the Martian surface appear to show larger deposits of kaolinite in other parts of the planet. However, Perseverance and other rovers have not yet explored these areas.
The presence of kaolinite on Mars reinforces the hypothesis that the Red Planet was a humid oasis sometime in the distant pastalthough exactly when and how it dried up continues to be debated.
Studying these ancient clays could give scientists more clues about how and when Mars lost its water, as well as its potential habitability.
