NASA’s Perseverance rover has been collecting samples from Mars since 2021, but one of its most recently collected rocks could help it achieve its goal of finding evidence of ancient life on the planet. Nicknamed Cheyava Falls after the tallest waterfall in the Grand Canyon, the 3.2 feet by 2 feet sample contains “chemical signatures and structures” that could’ve been formed by ancient microbial life from billions of years ago.
Perseverance collected the rock on July 21 from what was once a Martian river valley carved by flowing water long ago. The sample, which you can see in close up below and from afar at the center of the image above, exhibits large white calcium sulfate veins running along its length. They indicate that water did run through the rock at one point.
More importantly, it contains millimeter-size marks that look like “leopard spots” all over its central reddish band. On our planet, those spots could form on sedimentary terrestrial rocks when there are chemical reactions that turn hematite, one of the minerals responsible for Mars’ reddish color, to white. Those reactions can release iron and phosphate, which could’ve served as an energy source for microbes.
The rover’s Planetary Instrument for X-ray Lithochemistry (PIXL) tool already determined that the black rings around the spots contain iron and phosphate. However, that doesn’t automatically mean that the rock truly did serve as a host for ancient microbes.
The spots could’ve been formed by non-biological processes, and that’s something scientists will have to figure out. “We cannot say right now that we have discovered life on Mars,” Katie Stack Morgan, the deputy project scientist, said. “But what we are saying is that we have a potential biosignature, which is a set of features that could have a biological origin but do need further study and more data.”
NASA still has to bring back the samples Perseverance had collected to our planet, including Cheyava Falls. As The New York Times notes, the Mars Sample Return mission is years behind schedule and would not be able to bring back rocks from the red planet until 2040 instead of in the early 2030’s like originally planned. NASA recently asked aerospace companies for alternative solutions on how to get the samples to Earth much sooner and will finance their studies due later this year. Scientists will also have to conduct extensive testing to rule out contamination and non-biological processes, as well as other possible explanations for how the leopard spots had formed, before they can proclaim that they’re indeed evidence of ancient Martian life.