NASA’s Perseverance rover has found a rock on Mars that could hold the most convincing evidence yet of ancient microbial life. A rock nicknamed “Cheyava Falls,” located in the Jezero Crater revealed the trifecta discovery for its presence of water, organic compounds, and a potential chemical energy source.
According to Ken Farley, project scientist for Perseverance, Cheyava Falls is “the most puzzling, complex, and potentially important rock yet investigated by Perseverance.” It contains two vertical veins of calcium sulfate flanking a red band of rock that hosts what has been called “leopard spots.” Quite literally, the spots turn out to be a good indicator of chemical reactions that could have provided energy to old microbial life.
The find is all the more exhilarating because it brings together three critical elements—water, organic compounds, and chemical reactions—in one location. “We have our first compelling detection of organic material, distinctive colorful spots indicative of chemical reactions that microbial life could use as an energy source, and clear evidence that water, necessary for life, once passed through the rock,” Farley said.
Things get complicated, however, with the occurrence of millimeter-sized olivine crystals, a mineral that crystallizes from magma. It raises the question of whether the olivine and sulfate were incorporated into the rock at unbearably high temperatures, perhaps creating an abiotic chemical reaction to form leopard spots.
The Perseverance has been equipped with advanced tools, including SHERLOC and PIXL, to study these findings. But even with the rover’s suite of instruments, Farley stated that “scientifically, Perseverance has nothing more to give.” For scientists to understand the detailed geologic history of Jezero Crater, the Cheyava Falls sample would have to be returned to Earth for future analysis.
It is the first big scientific discovery made by Perseverance, launched with key mission objectives in astrobiology and sample caching that might hold signs of ancient microbial life. NASA, through the Mars Sample Return Program, is working in tandem with the European Space Agency on sending spacecraft to Mars to pick up these sealed samples and bring them back to Earth for future examination.
The evidence is tantalizing but far from conclusive. For example, the presence of organic molecules, calcium sulfate veins, and olivine crystals could all be explained through nonbiological processes. Much more work is needed to test these interpretations.
Results should deal another blow to the multibillion-dollar sample return program, which Perseverance was supposed to kick off. That is, if everything goes right, future missions will pick up the Cheyava Falls sample and ferry it back to Earth, where it would be probed in cutting-edge laboratories far superior to anything aboard Perseverance.
The question remains open as to whether, at present, Mars hosted microbial life, but certainly, the evidence collected by Perseverance makes the most promising case yet.