NASA finds potential fingerprint of microbial life on Mars
NASA's Perseverance Rover encountered a rock that formed in the vicinity of water, containing minerals that are associated with microbial life on Earth. A stunning aspect of the discovery is that the potential biosignature is more recent that scientists believed life could exist on Mars.
In July 2024, while exploring a set of rocky outcrops on the edges of an ancient river valley measuring 400 metres wide, NASA's Perseverance rover encountered a rock with features described as 'Leopard Spots'. Preliminary analysis indicated that this rock, dubbed 'Cheyava Falls' may contain potential biosignatures, which has subsequently been confirmed after a year of research. A paper describing the investigation has been published in Nature. The science instruments on board the rover were able to determine that the sedimentary rocks in the formation contain a combination of clay and silt, both of which preserve past microbial life excellently on Earth. The rock is also rich in organic carbon, sulphur, oxidized iron or rust, and phosphorous.
Lead author of the paper, Perseverance scientist Joel Hurowitz says, "The combination of chemical compounds we found in the Bright Angel formation could have been a rich source of energy for microbial metabolisms. But just because we saw all these compelling chemical signatures in the data didn’t mean we had a potential biosignature. We needed to analyze what that data could mean." These Leopard Spots on the rock could have been left behind by microbial life if it had used the raw ingredients available in the rock, the carbon, sulphur or phosphorous as an energy source. The spots contain two iron-rich minerals, vivianite normally found in sediments, peat bogs, and around decaying organic matter on Earth, as well as greigite, which is also produced by certain forms of microbial life on Earth.
Minerals in the rock indicate recent life
The combination of these minerals are a potential fingerprint of microbial life. The minerals can also be produced by abiotic processes, but the rock does not show any evidence of high temperature or acidic conditions within which these minerals could have formed abiotically. Scientists were particularly surprised by the discovery because the formation contained some of the youngest sedimentary rocks investigated by Perseverance. Based on previous observations, scientists had assumed that any signs of ancient microbial life would have been discovered on older rock formations. The discovery suggests that Mars may have been conducive to life for longer than previous estimates. Perseverance has collected 33 samples on the Red Planet so far, and NASA has previously indicated that these samples are of biological relevance.