NASA’s Perseverance rover has found hundreds of unusually bleached rocks on Mars which are wealthy in a mineral troublesome to kind with out long-term publicity to water, including recent proof that the Purple Planet was hotter, wetter and probably rain-soaked billions of years in the past.
The newfound Mars rocks are wealthy in kaolinite, a smooth, white, clay mineral that, on Earth, usually types when water slowly leaches different parts from rock over hundreds to hundreds of thousands of years, a brand new examine stories. On Earth, it’s mostly present in heat, humid environments similar to rainforests, the place frequent rainfall drives intense chemical weathering.
“You want a lot water that we predict these may very well be proof of an historical hotter and wetter local weather the place there was rain falling for hundreds of thousands of years,” added examine co-author Briony Horgan, who’s a professor of planetary science within the Division of Earth, Atmospheric and Planetary Sciences at Purdue College and a long-term planner on the Perseverance mission.
Perseverance recognized a number of thousand of those kaolinite-rich rocks — starting from small pebbles to giant boulders — scattered throughout the floor of Jezero crater, the dry, bowl-shaped despair simply north of Mars’ equator that seemingly held a lake billions of years in the past.
Since touchdown on Mars in 2021, the car-sized robotic has explored the crater flooring looking for proof of previous microbial life. Late final yr, it climbed up the crater’s internal wall and onto the rim, exploring new terrain. Scientists are attempting to grasp how that wetter period ended, when Mars misplaced its world magnetic area and particles from the solar started stripping away its thick ambiance, reworking the planet into the chilly, barren world seen in the present day.
Whereas kaolinite-bearing terrains on Mars had beforehand been recognized from orbit, Perseverance’s discoveries permit scientists to check such supplies immediately on the planet’s floor, the examine notes.
To higher perceive how the Martian rocks fashioned, Broz and his group in contrast Perseverance information with kaolinite deposits on Earth, together with revealed information from Southern California and South Africa. The chemical signatures intently matched, strengthening the case that the Martian rocks fashioned by way of rainfall-driven weathering moderately than volcanic or hydrothermal processes, in keeping with the brand new examine.
One lingering thriller the group remains to be attempting to resolve is the place the rocks got here from.
There isn’t any apparent close by bedrock supply, in keeping with the examine. The closest potential origin lies about 1.2 miles (2 kilometers) away, the place orbital information reveals signatures per kaolinite in giant chunks of fractured rock created by historical impacts. Researchers additionally level to areas alongside the stretches of Neretva Vallis, a river channel that when flowed into Jezero crater.
“They’re clearly recording an unimaginable water occasion, however the place did they arrive from?” Horgan stated within the assertion. The rocks might have been carried into the crater by historical rivers or blasted there by meteorite impacts, he added. “We’re not completely positive.”
These findings are described in a paper revealed in December of 2025 within the journal Nature Communications Earth & Setting.
