Potential alien life has been discovered on a crater on Mars - and humans and animals could be responsible, scientists say. Nasa's Perseverance rover found diverse organic matter in the Jezero crater, which experts say suggests a more complex system than previously thought may have existed in the past.
A number of different explanations for the origins of organic matter on the Red Planet include water-rock interactions and biotic origins - derived from living organisms.
Deposits by interplanetary dust or meteors are also being considered by scientists. According to the study, understanding more about Martian organic matter could shed light on the availability of carbon sources, with implications for the search for potential signs of life.
The Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (Sherloc) instrument on the rover is the first tool to enable fine-scale mapping and analysis of organic molecules and minerals on Mars.
Perseverance landed within the Jezero crater, the site of an ancient lake basin with high potential for past habitability, in February 2021.
Since then scientists have been exploring the geological make-up of the crater floor using a suite of tools on board the rover that can take pictures of and analyse the rocks. Sunanda Sharma, Ryan Roppel and their colleagues analysed observations from two formations on the Jezero crater floor.
Signals of organic molecules were detected on all 10 targets that Sherloc observed in the Jezero crater floor, concentrated in the Maaz formation, more than in the Seitah formation. The data showed diverse mineral association and spatial distribution that may be unique to each formation.
The researchers suggest the diversity among these observations may provide insight into different ways that organic matter may have originated: potentially through deposition by water, or in combination with volcanic materials.
Writing in the Nature journal, the authors said: "Our findings suggest there may be a diversity of aromatic molecules prevalent on the Martian surface, and these materials persist despite exposure to surface conditions.
"These potential organic molecules are largely found within minerals linked to aqueous processes, indicating that these processes may have had a key role in organic synthesis, transport or preservation."