NASA’s Perseverance rover has reached a scientifically thrilling region on Mars called Krokodillen, where some of the planet’s oldest rocks may hold vital clues about early Martian environments — possibly even ancient life.
Rich in clay, olivine, and carbonate minerals, the site promises insights into the watery past of Mars, especially during the Noachian period.
Exploring Krokodillen: A New Martian Frontier
NASA’s Perseverance rover has started exploring a brand new area on Mars called “Krokodillen,” and scientists are excited. This rocky region might hold some of the oldest rocks ever found on the Red Planet. It’s located at a key boundary between the rugged rim of Jezero Crater and the plains beyond, making it a prime spot for unlocking secrets about Mars’ distant past.
“The last five months have been a geologic whirlwind,” said Ken Farley, 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.”
Krokodillen is named after a mountain ridge in Norway and means “the crocodile” in Norwegian. It stretches across 73 acres of rocky terrain and sits just downslope from Witch Hazel Hill. But what makes this place truly special is what’s hidden in the rocks.
Krokodillen’s Ancient Clays: Traces of Water and Life
Early findings show that clay minerals are present in Krokodillen’s bedrock. That’s a big deal because clays only form in the presence of liquid water, which means this area may have been wet billions of years ago. (This was likely before Jezero Crater was formed by the impact of an asteroid.) On Earth, clay is also excellent at preserving organic compounds—the chemical building blocks of 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,’” said Farley, referring to a rock sampled in July 2024 with chemical signatures and structures that could have been formed by life long ago. “The Krokodillen rocks formed before Jezero Crater was created, during Mars’ earliest geologic period, the Noachian, and are among the oldest rocks on Mars.
NASA program scientist Lindsay Hays explains what defines potential signs of ancient life on other worlds and why they require future study. NASA’s Perseverance Mars rover is searching for these signs, collecting samples for future return to Earth, and helping pave the way for human exploration. Credit: NASA/JPL-Caltech
Carbonates and Olivine: Martian Rock Chemistry
Data collected from NASA’s Mars orbiters suggest that the outer edges of Krokodillen may also have areas rich in olivine and carbonate. While olivine forms from magma, carbonate minerals on Earth typically form during a reaction in liquid water between rock and dissolved carbon dioxide. Carbonate minerals on Earth are known to be excellent preservers of fossilized ancient microbial life and recorders of ancient climate.
The rover, which celebrated its 1,500th day of surface operations on May 9, is currently analyzing a rocky outcrop in Krokodillen called “Copper Cove” that may contain Noachian rocks.
The rover’s arrival at Krokodillen comes with a new sampling strategy for the nuclear-powered rover that allows for leaving some cored samples unsealed in case the mission finds a more scientifically compelling geologic feature down the road.
Bell Island and the Case of the Unsealed Tube
To date, Perseverance has collected and sealed two regolith (crushed rock and dust) samples, three witness tubes, and one atmospheric sample. It has also collected 26 rock cores and sealed 25 of them. The rover’s one unsealed sample is its most recent, a rock core taken on April 28 that the team named “Bell Island,” which contains small round stones called spherules. If at some point the science team decides a new sample should take its place, the rover could be commanded to remove the tube from its bin in storage and dump the previous sample.
“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,” said Perseverance acting project scientist Katie Stack Morgan of NASA’s Jet Propulsion Laboratory in Southern California. “There are seven empty sample tubes remaining and a lot of open road in front of us, so we’re going to keep a few tubes — including the one containing the Bell Island core — unsealed for now. This strategy allows us maximum flexibility as we continue our collection of diverse and compelling rock samples.”
Clean Enough: Safeguarding Sample Integrity
Before the mission adopted its new strategy, the engineering sample team assessed whether leaving a tube unsealed could diminish the quality of a sample. The answer was no.
“The environment inside the rover met very strict standards for cleanliness when the rover was built. The tube is also oriented in such a way within its individual storage bin that the likelihood of extraneous material entering the tube during future activities, including sampling and drives, is very low,” said Stack Morgan.
In addition, the team assessed whether remnants of a sample that was dumped could “contaminate” a later sample. “Although there is a chance that any material remaining in the tube from the previous sample could come in contact with the outside of a new sample,” said Stack Morgan, “it is a very minor concern — and a worthwhile exchange for the opportunity to collect the best and most compelling samples when we find them.”
Perseverance is NASA’s most advanced Mars rover, designed to explore the surface of the Red Planet and search for signs of ancient life. It launched on July 30, 2020, and successfully landed in Jezero Crater on February 18, 2021.
Equipped with cutting-edge scientific instruments, Perseverance is investigating Mars’ geology, climate, and past habitability. A major goal is to collect and cache rock and soil samples that may one day be returned to Earth by a future mission. The rover also carries Ingenuity, a small experimental helicopter that made history by performing the first powered flight on another planet.
Perseverance is helping scientists piece together Mars’ environmental history, especially by analyzing ancient river deltas, crater rims, and regions rich in clay and carbonate minerals—key ingredients for life. The mission is part of NASA’s broader effort to pave the way for human exploration of Mars.
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