Scientists have found a unique geological formation in the Atacama Desert, known as Red Stone, that provides important clues for the search for life on Mars. The site contains an unusual abundance of microorganisms, including a “dark microbiome” with high levels of uncertainty about their classification. The mix of biosignatures from extant and ancient microorganisms can be difficult to detect with current laboratory equipment, and it may be even harder to detect on Mars. The study stresses the importance of returning samples to Earth for conclusive testing. Analyses of Red Stone samples using rover testbeds have unveiled the importance of wet chemistry derivatization experiments for detecting organics in mass spectrometers, and the SOLID immunoassay approach for detecting microbial life. However, the limited detection of biosignatures by testbed instruments highlights the critical importance of a Mars Sample Return mission. Red Stone is an exceptional analog model site for studying the formation and habitability of an ancient alluvial fan/fan delta that formed under arid conditions in a Mars analog setting.

https://doi.org/10.1038/s41467-023-36172-1