Because the Perseverance rover traversed an historic river valley in Mars’ Jezero Crater again in July 2024, it drilled into the outside and extracted a pattern from of a novel, striped rock referred to as Chevaya Falls. The rover’s tools then analyzed the pattern, which is named Sapphire Canyon, and surveyed the encompassing rock.
When scientists began having a look into the information, they discovered two kinds of iron-rich minerals organized at the rock in a particular, noticed trend. Each those minerals are related to existence on Earth. One is located round decomposing natural topic on Earth, whilst the opposite is produced by means of sure microbes.
A group of researchers made up our minds in a learn about printed Sept. 10, 2025, that the pattern incorporates a possible biosignature – which might recommend the crimson planet as soon as hosted microbial existence.
Those minerals could have shaped at the rock when historic microbes used chemical reactions to supply power. However chemical reactions now not associated with existence too can produce those minerals below sure prerequisites.
To be informed extra, The Dialog U.S. requested Amy J. Williams, an astrobiologist on the College of Florida, about biosignature looking on Mars and what’s so particular about this Sapphire Canyon pattern.
What are biosignatures?
A biosignature is any feature, component, molecule, substance or characteristic that serves as proof for previous or provide existence. It should be one thing that can’t be produced with out existence. Some examples come with fossils, natural molecules derived from a organic procedure, or mineral patterns that shape handiest via microbial job.
There are six kinds of biosignatures that scientists would possibly in finding on Mars.
The Planetary Society, CC BY
A possible biosignature, which is how the Sapphire Canyon discovering is described, is a substance or construction that may have a organic starting place however calls for extra knowledge or additional learn about earlier than scientists could make a conclusion concerning the absence or presence of existence.
How do scientists resolve whether or not one thing is usually a biosignature on Mars?
Biosignatures are available in many various flavors – chemical, bodily or structural. Some are somewhat evident, like a dinosaur fossil on Earth, however maximum are way more nuanced.
The seek for historic existence on Earth partly informs the seek for biosignatures on Mars. Researchers depend on delicate clues preserved within the rock report to deal with questions comparable to how way back microbial existence arose on Earth. We seek for that proof in environments comparable to craters and lake beds with top preservation attainable, which means the ones which might be more likely to maintain the biosignatures.
Scientists can practice those ways to the seek for existence on Mars. Because of this Perseverance used to be despatched to Jezero Crater. Within the historic previous, the crater hosted a river-fed lake, which on Earth would constitute a liveable surroundings: one the place existence would need to reside if it ever arose.
This crater used to be a great location to seek for historic existence preserved within the rock report on Mars. Astrobiologists then seek for chemical, textural and mineral patterns that resemble processes influenced by means of existence again on Earth.
What makes this pattern distinctive and fascinating?
The Sapphire Canyon pattern is exclusive as a result of Perseverance’s PIXL and SHERLOC tools printed unique textures that have been dubbed “leopard spots.” Those spots are concentric response fronts – puts the place chemical and bodily reactions happen – enriched within the minerals vivianite, which incorporates iron phosphate, and greigite, which is product of iron sulfide.
Chevaya Falls, a rock within the Martian Jezero Crater, is speckled with ‘leopard spots,’ which might point out chemical reactions that can have as soon as supported historic existence.
NASA/JPL-Caltech/MSSS
On Earth, vivianite steadily bureaucracy in environments with a whole lot of decaying natural topic, whilst sure microbes that use sulfate for power can produce greigite. Compounds in each those minerals are a part of a chemical procedure referred to as redox gradients, which refers to a chain of slow adjustments over bodily area the place chemical substances can oxidize (lose electrons) or cut back (acquire electrons).
One instance is leaving your steel motorcycle out within the rain. Over the years, the decreased iron (Fe2+) will lose an electron and oxidize to rust (Fe3+). This procedure can occur nonbiologically, as publicity to water and oxygen force the chemical adjustments that take your new motorcycle to a rusty motorcycle – I recommend now not leaving it within the rain.
However some oxidation and relief processes are so gradual on their very own that the one approach they may be able to happen is with dwelling organisms that push the reactions ahead. This procedure is what number of microbes, comparable to micro organism, get the power to reside. As a result of those two minerals within the Sapphire Canyon pattern each happen in redox gradients, scientists expect that microbial existence, if it used to be ever provide, may have performed a task within the reactions that created those mineral signatures.
Now, scientists are having a look into the reasons that wouldn’t require existence to shape those options at the pattern.
Did scientists anticipate finding a pattern like this?
This used to be a discovering that we had was hoping for. On the other hand, it used to be fairly surprising on this explicit location. This pattern got here from one of the youngest sedimentary rocks the project has investigated so far. An previous prediction had assumed indicators of historic existence would come from older Martian rock formations.
Discovering those options in more youthful rocks widens the window of time that Mars used to be doubtlessly liveable and means that Mars may have been liveable later within the planet’s historical past than scientists prior to now idea, and older rocks may additionally dangle indicators of existence which might be merely tougher to stumble on.
NASA hosted a press convention on Sept. 10, 2025, concerning the mysterious pattern.
What are the following steps to inform whether or not the pattern signifies indicators of previous existence, or whether or not the signature is from a nonbiological procedure?
The mineral associations are a possible fingerprint for the ones redox reactions that may happen when microbes force the response ahead – however abiotic processes, comparable to sustained top temperatures, acidic prerequisites and binding by means of natural compounds, may just additionally give an explanation for them.
On the other hand, the Cheyava Falls rock presentations no indicators that it’s been uncovered to the top warmth or acidity generally required for greigite and vivianite to shape nonbiologically. Nonetheless, the one definitive approach to reply to this query is to go back the pattern to Earth, the place scientists can use complex laboratory ways to tell apart organic from nonbiological origins.
