The discovery is among the strongest evidence yet that the red planet may have once harbored life. However, scientists say more study is needed, ideally in labs on Earth.
The mission of the Perseverance rover is to determine if there was once microscopic life on MarsImage: NASA/JPL-Caltech/MSSS/REUTERS
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NASA's rover Perseverance has uncovered rocks that may hold potential signs of ancient microbial life on Mars, according to research published Wednesday.
Since landing on the Martian surface in 2021, the rover has been searching for signs of ancient life in Jezero Crater, a region in the planet's northern hemisphere that was once flooded and contained an ancient lake basin.
In summer 2024, Perseverance discovered newly identified "Sapphire Canyon" rock samples in the reddish, clay-rich mudstones of Neretva Vallis, a river channel that once carried water into Jezero Crater. The samples were then examined using all the scientific instruments aboard the rover.
NASA's science mission chief, Nicky Fox, acknowledged that the latest analysis "is certainly not the final answer," but said it's "the closest we've actually come to discovering ancient life on Mars."
What do scientists say?
Stony Brook University planetary scientist Joel Hurowitz, who led the study published in the journal Nature, said that researchers detected a "potential biosignature" in multi-billion-year-old sedimentary rocks.
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These potential biosignatures took the form of two minerals that appear to have formed from chemical reactions between mud and the organic matter present in it, Hurowitz said.
The minerals are vivianite, an iron phosphate, and greigite, an iron sulfide. "These reactions appear to have taken place shortly after the mud was deposited on the lake bottom. On Earth, reactions like these, which combine organic matter and chemical compounds in mud to form new minerals like vivianite and greigite, are often driven by the activity of microbes," Hurowitz explains.
Vivianite is often found in sediments and peat bogs on Earth, as well as in areas with decaying organic matter. Some forms of microbial life can produce greigite. "The microbes are consuming the organic matter in these settings and producing these new minerals as a byproduct of their metabolism," he added.
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More study needed on Earth
Although scientists cannot say with certainty that they have found signs of ancient microbial life, they consider the findings to be convincing.
"It's kind of the equivalent of seeing like leftover fossils, you know, leftovers from a meal, and maybe that meal has been excreted by a microbe. And that's what we're seeing in this sample," Nicky Fox, administrator of NASA's Science Mission Directorate, told journalists.
Hurowitz explained that researchers would need to analyze the sample in person to determine whether microbial activity had created the fantastic textures and colors, including blue and green.
Ideally, this analysis would be conducted in labs on Earth before drawing any conclusions. "There are non-biological ways to make these features that we cannot completely rule out on the basis of the data that we collected," Hurowitz said.
However, bringing the samples back to Earth could be challenging, especially since the Trump administration is considering canceling the Mars Sample Return program.
According to Hurowitz, until samples are transported off Mars by robotic spacecraft or astronauts, scientists will have to rely on earthly stand-ins and laboratory experiments to evaluate the feasibility of ancient Martian life.
NASA's rover Perseverance has landed on Mars
Perseverance is NASA's fifth Mars rover and its biggest and heaviest to date. Its mission on the Red Planet has started this Thursday.
Image: NASA/JPL-Caltech
A new rover for the red planet
NASA's Mars 2020 Perseverance rover (shown in artist's illustration) is the most sophisticated rover NASA has ever sent to Mars. Ingenuity, a technology experiment, will be the first aircraft to attempt controlled flight on another planet. Perseverance touched down at Mars' Jezero Crater on February 18, 2021 at about 20:57 UTC with Ingenuity attached to its belly.
Image: NASA/JPL-Caltech
Everything prepared
NASA engineers loaded the Mars rover Perseverance onto an Atlas V rocket at the start of July 2020. The rocket took off on July 30 from Cape Canaveral, Florida. The rover arrived at the orbit around Mars in early February 2021.
Image: NASA
Presentation in a clean room
This is how Perseverance looked when it was presented to the public in 2019. The rover will support NASA's Curiosity rover, the most modern rover until Perseverance came along. The new rover weighs a little over a ton — 100 kg (220 pounds) more than its predecessor. And at 3 meters (10 ft) long, it's also 10 centimeters longer as well.
Image: NASA/JPL-Caltech
More performance
Perseverance can be loaded with more research instruments and sensors than its predecessor. And its gripper arm, with its cameras and tools, is stronger, too. The rover can collect samples from Mars. It's got 23 cameras and many other instruments. One mission is to test whether it's possible to extract oxygen from Martian rock. But, hey, what's that standing next to the rover on the ground?
Image: NASA/JPL-Caltech
A small drone
That's right! Perseverance has a helicopter onboard. That's never happened on a planetary mission before. The helicopter is completely new territory for its developers. It will be the first time they're able to experience and collect data from flight in atmospheric conditions that are different from those on Earth, and in a gravity that is about a third of our own.
Image: NASA/Cory Huston
The robotic giant
Curiosity is the largest and most modern of all Mars rovers currently deployed. It landed on August 6, 2012, and has since traveled more than 21 kilometers (13 miles). It is much more than just a rover. Its official name is "Mars Science Laboratory," and it really is a complete lab on wheels.
Image: picture-alliance/dpa/Nasa/Jpl-Caltech/Msss
What's in it?
For example, it contains a special spectrometer, which can analyze chemical compounds from a distance with the help of a laser; a complete meteorological station that can measure temperature, atmospheric pressure, radiation, humidity and wind speed; and most importantly, a chemistry lab that can run detailed analyses of organic compounds and is always on the hunt for traces of alien life.
Image: NASA/JPL-Caltech/MSSS
Not just scratching the surface
Curiosity has shown that life would theoretically be possible on Mars. But it hasn't discovered any life, yet. The robot's arm is equipped with a full power drill. Here, it's taking a sample in "Yellowknife Bay" inside the Gale Crater.
Image: NASA/JPL-Caltech
Off to the lab!
The Mars dust is processed by a large number of instruments. First, it's filtered and separated into different-sized particles. Then, those get sorted and sent off to different analytical laboratory machines.
Image: picture alliance/AP Photo/NASA
A tiny predecessor
Curiosity's predecessors were much smaller. On July 4, 1997, the small Mars rover Sojourner left its first tire tracks behind in the dust of the red planet. It was the first time a mobile robot had been left to its own devices there, equipped with an X-ray spectrometer to conduct chemical analyses and with optical cameras.
Image: NASA/JPL
Size comparison
Three rover generations. (The tiny one up front is Sojourner.) At 10.6 kilograms (23 pounds), it's not much bigger than a toy car. Its top speed: 1 centimeter per second. Opportunity weighs 185 kilograms — roughly the equivalent of an electric wheelchair. Curiosity is as big as a small car, at 900 kilograms. The big ones travel up to 4 or 5 centimeters per second.
Image: NASA/JPL-Caltech
Almost four months of duty
Sojourner travelled about 100 meters during its lifetime and delivered data and pictures until September 27, 1997. This is one of the last pictures of it, taken nine days before the radio connection broke down. Sojourner probably died because the battery did not survive the cold nights.
Image: NASA/JPL
Paving the way for tomorrow's technology
Without the experience of Sojourner, newer rovers could have hardly been envisaged. In 2004, NASA landed two robots of the same model on Mars: Spirit and Opportunity. Spirit survived for six years, travelling a distance of 7.7 kilometers. The robot climbed mountains, took soil samples and withstood winter and sandstorms. Its sibling, Opportunity, lost contact on February 13, 2019.
Image: picture alliance/dpa
Lots of gadgets
Opportunity passed the marathon distance of 42 kilometers back in 2015, and to this day, it has covered much more ground than Curiosity. It can take ground probes with its arm. It has three different spectrometers and even a 3D camera. It was last operating in "Perseverance Valley," an appropriate workplace for the sturdy robot, before being incapacitated by a sandstorm.
Image: picture-alliance/dpa
The red planet's landscapes
This panorama was taken by Curiosity's mast camera. The most modern of the rovers will stay in service as long as possible — hopefully at least another five years. The Martian landscape looks familiar somehow, not unlike some deserts here on Earth. Should we give in to our wanderlust, then — or would it be better leave Mars to the robots?
