Was there life on Mars? This question is still unclear. But the Marsrover “Perseverance” has now discovered a stone formation on the red planet, which at least raises questions. Because in the fine-grained clay minerals of a former river bed in the Jezero crater, the analysis instruments of the NASA rovers identified tiny granules made of iron sulfide and iron phosphates as well as traces of chemical reactions with organic carbon compounds. On earth, such formations typically arise from the activity of microbes, as the researchers explain. You therefore see potential biosignatures in these “leopard spots”. However: Such chemical traces can also arise from abiotic reactions, for example in the event of heat or in the presence of acids. Whether the “Cheyava Falls” is actually baptized is the long -sought testimony of past life on Mars can therefore only clarify rehearsals brought back to earth.
Mars could have been very similar in its early days: he had a mild climate, a denser atmosphere than today as well as lakes, rivers and maybe even oceans. The red planet was quite life -friendly until around 3.5 billion years ago. Among other things, evidence of deposits from clay minerals formed in the presence of water, but also old river valleys and other landscapes that may be characterized by water. That is why planet researchers have been searching for years that at least microbial life has developed on the young Mars. In fact, several Marsonden and Rover have already discovered chemical and geological traces, for which a biological origin is at least not excluded. In the spring of 2025, for example, this was the case at the Marsrover Curiosity: In rehearsals by Tonstein, the rover hydrocarbons with up to twelve carbon atoms – potential degradation products from long -chain fatty acids, such as those occurring in cell membranes of organisms. However, these Marsian alkanes could also have arisen abiotic. They are therefore not clear biosignature.
Iron minerals and organic compounds
Now the Marsrover “Perseverance” has also discovered a potential biosignature – with similar restrictions. The NASA-Rover has been exploring the 45-kilometer Jezero crater since 2021, in which there have been traces of an old river bed and deposits of a past lake, as have been shown to date. The task of the Perseverance Rovers is to look for potential traces of past life in this promising environment. The Rover Neretva Vallis, a former river valley in the north of the crater, has been exploring the Rover Neretva Vallis since 2024. There is an extensive, “Bright Angel” baptized rock formation, which mainly consists of fine -grained clay minerals. On the surface of a rocky brocken – “Cheyava Falls” – “Cheyava Falls” – showed camera shots of the rover unusual structures: dozens, only a few millimeters small, irregularly shaped stains with light inner and an outer ring made of black material. In between there were even smaller dark dots. The NASA floor team gave these traces the nicknames of leopard spots and poppy seeds because of their appearance.
But what are these spots? To find out that, Perseverance used several of his analysis instruments, including the Sherloc RAM spectrometer. The chemical analyzes showed that both the larger spots and the small dots are enriched with two iron -containing minerals: the hydrated iron phosphate Vivianit and the iron sulfide Greigit. Both minerals also occur on earth in water -rich environments. However, the analyzes also showed that there are chemical reaction fronts on the edge of these small mineral accumulation, which indicate a redox reaction of this mineral in the presence of organic carbon compounds. “This common occurrence of organic material and redox-sensitive minerals is very exciting,” explains co-ortor Michael Tice from Texas A & M University. “Because it suggests that the organic molecules played a role as drivers of the reactions that these minerals once formed.” In this type of mineral formation, microbes are usually in the game on earth. “They arise in sediments in which microbes are giving up organic matter and releasing rust and sulfate,” said Tice. “The presence of these connections on Mars therefore raises the question: Could similar processes have expired there?”
Possible reference to microbial participation
According to the researchers, the “leopard spots” and “poppy seeds” on the rock surface of Cheyava Falls could be potential biosignatures-with emphasis on “potentially”: “This is a very exciting discovery, but it does not mean that we have found life on Mars,” emphasizes co-author Sanjeev Gupta from Imperial College London. Because the minerals identified by Perseverance could also have arisen abiotic – without the participation of microbes. There are reaction routes through which such iron -containing sulfides and phosphates are also created purely geochemically. However, either heat or the presence of an acid is necessary. “However, the previously possible studies indicate that these rocks have never been adequately heated to create the leopard stains and poppy seeds,” says Tice. So far there have been no clear indications of an acidic environment. “If this is confirmed, we must seriously consider that these formations were produced by bacteria -like beings that lived in the mud of a Marsian lake more than three billion years ago,” continued the researcher.
However, there are still more precise analyzes to confirm or invalidate this scenario. Because the on-board instruments of the Perseverance Rovers cannot carry out the necessary examinations. “We have to examine these rock samples on earth in order to be able to answer this question,” says Guppa. Fortunately, the chances are good: The Perseverance Rover has already drilled a rock test of this formation and, together with other samples, deposited in special containers at a storage location. These samples are then to be collected by another mission mission – probably in the 2030s – and brought back to earth. Only then can the potential biosignatures from the Jezero crater be checked in more detail by earthly laboratories. “Astrobiological Claims, especially those associated with the potential discovery of past extraterrestrial life, require exceptionally good evidence,” emphasizes co-author Katie Stack Morgan from the Perseverance team at the Jet Propulsion Laboratory of NASA. So everything is still open.
Source: Joel Hurowitz (Stony Brook University, New York) et al., Nature, DOI: 10.1038/S41586-025-09413-0
