A fresh discovery made by the NASA Perseverance rover has sparked a ripple of excitement among scientists, it points toward possible ancient microbial life on Mars. While investigating the northern rim of Neretva Vallis, an ancient river valley that once channeled water into Jezero crater, the rover stumbled upon a very interesting arrowhead-shaped rock on July 21, called Cheyava Falls.
This 3-by-2-foot rock, sporting some very interesting surface spots and vein-like features, has been assessed by Ken Farley, the mission’s project scientist from the California Institute of Technology, as “the most puzzling, complex and potentially important rock yet investigated by Perseverance,” The analysis of this rock showed signs of organic material and evidence of past water flow, both critical indicators in the search for life.
Farley added an emphasis on the twofold nature of the findings: “On the one hand, 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. On the other hand, we have been unable to determine exactly how the rock formed and to what extent nearby rocks may have heated Cheyava Falls and contributed to these features.”
It is the complex features in this rock that most fascinate astrobiologists. David Flannery, an astrobiologist at the Queensland University of Technology, said the Cheyava Falls spots were a “big surprise” because on Earth similar features are usually associated with fossilized microbes.
The rock itself contains large white veins of calcium phosphate and bands of reddish material, probably haematite, that gives Mars its rusty color. On closer inspection, there were many features resembling leopard spots, each surrounded by a black ring enriched in iron and phosphate. This could have resulted from chemical reactions of haematite, which created iron and phosphate, and possibly supplied energy to microbial life.
Yet scientists are treading cautiously, and so far nothing examined has been considered concrete proof of fossilized microbes. Much more research is needed. The pressure to get to the bottom of this discovery is huge, but NASA’s Mars sample return mission is mired by overruns and delays. It currently overshoots its budget by $11 billion and is not due to return samples before 2040. The space agency is scouring for alternatives to hurry up the process while slashing down the costs.
For John Bridges, a participating scientist on NASA’s Mars Science Laboratory mission, that made the case for bringing those samples back to Earth for detailed analysis all the more compelling. “We have never seen anything like this from Mars before,” he said, underlining the need for sophisticated electron microscopy and isotope analysis to establish whether the features formed through ancient microbial action or non-biological processes.
Charles Cockell, an astrobiologist at the University of Edinburgh, however, says that the features do not provide any unequivocal proof of life, but they confirm Mars was a dynamic planet with all the ingredients for life, including organic carbon. He urges future missions to bring back samples, or better yet, send humans to Mars and investigate.
While most of the scientific community is holding its breath for the next developments, the discovery of Cheyava Falls speaks vividly of ancient Mars and more precisely of a search that has been underway for a long while for indications of life beyond Earth.