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NASA's Perseverance Rover is digging into 'Krokodillen' to explore some of the oldest Martian rocks

The clay in this ancient bedrock could give clues about the presence of water, and it is a boundary between the planet’s past and present.

BY MAHALEKSHMI P

PUBLISHED MAY 24, 2025

NASA's Perseverance (Mars 2020) rover uses its drill to core a rock sample and will store it for future missions in the area known as Jezero crater on the planet Mars. (Representative Cover Image Source: Getty Images | NASA)

NASA’s Perseverance Mars rover is investigating a region called “Krokodillen,” known for having the oldest rocks on the planet. The region was a significant layer between the old rocks of Jezero Crater’s rim and the plains past it, per NASA. “The last five months have been a geologic whirlwind,” stated Ken Farley, the deputy project scientist for Perseverance from Caltech in Pasadena. “As successful as our exploration of ‘Witch Hazel Hill’ has been, our investigation of Krokodillen promises to be just as compelling,” he said about the Perseverance science team’s wishlist area.

NASA’s Perseverance rover fires up its descent stage engines as it nears the Martian surface to land in the area known as Jezero crater on the planet Mars. (Representative Photo illustration by NASA via Getty Images) — NASA’s Perseverance rover fires up its descent stage engines as it nears the Martian surface to land in the area known as Jezero crater on the planet Mars. (Representative Image Source: Getty Images | Illustration by NASA)

Krokodillen translates to “the crocodile” in the Norwegian language and it was named by the scientists of the Perseverance mission after a mountain ridge on the island of Prins Karls Forland, Norway. The area is a 73-acre rocky plateau situated to the west and south of Witch Hazel Hill. It was found earlier that the region harbored clay in its bedrock, and this clay was required for the formation of liquid water. Finding clay in other regions of Krokodillen can reinforce the presence of abundant liquid water in the Martian past, likely before the formation of the Jezero Crater, by the asteroid impact.

Angular and smooth surface of rocks are seen in an image taken by the panoramic camera on the Mars Exploration Rover Spirit on January 6, 2003. (Photo by NASA/Jet Propulsion Laboratory/ Cornell University via Getty Images) — Angular and smooth surfaces of rocks are seen in an image taken by the Mars Exploration Rover Spirit on January 6, 2003. (Representative Image Source: Getty Images | NASA/Jet Propulsion Laboratory/Cornell University)

Minerals of clay could be useful for life, as on Earth, these components have preserved organic compounds. The team found a rock sample in July 2024 with chemical signatures and structures of past life. “If we find a potential biosignature here, it would most likely be from an entirely different and much earlier epoch of Mars’ evolution than the one we found last year in the crater with ‘Cheyava Falls,’” stated Farley. “The Krokodillen rocks formed before Jezero Crater was created, during Mars’ earliest geologic period, the Noachian,” he added about the ancient rocks.

NASA's Phoenix Mars Lander's solar panel and the lander's Robotic Arm with a sample in the scoop. (Representative Photo by Stocktrek Images / Getty Images) — NASA's Phoenix Mars Lander's solar panel and the lander's Robotic Arm with a sample in the scoop. (Representative Image Source: Getty Images | Stocktrek Images)

NASA’s Mars orbiters presented information that hinted at rich olivine and carbonate on the outer edges of Krokodillen. Olivine formed from magma, but carbonate minerals resulted from a reaction between rock and dissolved carbon dioxide in liquid water, per NASA. Carbonate minerals on Earth preserve fossilized ancient microbial life and track ancient climate. Presently, the rover is investigating a rocky outcrop in Krokodillen known as “Copper Cove.” This region may contain evidence of Noachian rocks from the past of Mars.

The Echus Chasma, one of the largest water source regions on Mars, is pictured from ESA's Mars Express. The data was acquired on September 25, 2005. (Representative Photo by ESA via Getty Images) — The Echus Chasma, one of the largest water source regions on Mars, is pictured from ESA's Mars Express. The data was acquired on September 25, 2005. (Representative Image Source: Getty Images | ESA)

The exploration of Krokodillen will also test the nuclear-powered rover’s new sampling strategy. It allowed for samples to be left open in case the rover identifies a better and scientifically compelling geologic feature ahead. The recent unsealed sample of the rover is a rock core named “Bell Island,” with small round stones called spherules. If a better sample is identified, the rover will be directed to remove the tube from storage and dump the previous sample. Perseverance has collected and sealed two regolith samples, three witness tubes, and one atmospheric sample.

NASA's Ingenuity Mars Helicopter stands on the Red Planet's surface as NASA's Mars 2020 Perseverance rover rolls away. (Representative Photo illustration by NASA via Getty Images) — NASA's Ingenuity Mars Helicopter stands on the Red Planet's surface as NASA's Mars 2020 Perseverance rover rolls away. (Representative Image Source: Getty Images | Illustration by NASA)

“We have been exploring Mars for over four years, and every single filled sample tube we have on board has its own unique and compelling story to tell,” stated Perseverance acting project scientist Katie Stack Morgan of NASA’s Jet Propulsion Laboratory in Southern California. The team has only a few empty sample tubes remaining so they have decided to keep them unsealed for now, in case they chance upon better findings.