Potential biosignatures: Nasa scientists hail signs in rocks of ancient life on Mars

Unusual features found in rocks on Mars may be the handiwork of ancient microbial life that eked out an existence on the red planet billions of years ago.

- Ian Sample Richard Luscombe

The rocks were spotted by Nasa's Perseverance rover as it trundled along Neretva Vallis, an ancient river valley that was carved into the landscape by water flowing into the Jezero crater in the planet's distant past.

The rover, which touched down in the Jezero crater in 2021, encountered the rocks last year as it explored an outcrop called the Bright Angel formation on the northern edge of the valley. "This very well could be the clearest sign of life that we've ever found on Mars," Sean Duffy, Nasa's acting administrator, told a press conference at its Washington DC headquarters yesterday.

Instruments onboard the rover detected signs of carbon-based compounds in the rocks, while images captured intriguing surface spots and nodules that are often associated with microbial life on Earth.

The features may have prosaic origins in the form of chemical reactions that played out over millennia. But in a report published in Nature yesterday, the findings of which were discussed at the press conference, scientists say the features should be regarded as potential signs of life.