NASA’s Perseverance rover has found tantalizing evidence that suggests the Red Planet may have hosted microbial life some billions of years ago.
The rover came across a peculiar “vein-filled rock” nicknamed Cheyava Falls. The arrowhead-shaped rock is roughly 3 feet long and 2 feet wide. The rock’s unique composition suggests it may have once harbored microscopic life.
“Cheyava Falls is the most puzzling, complex, and potentially important rock yet investigated by Perseverance,” said Ken Farley, Perseverance project scientist of Caltech in Pasadena.
On July 21, the rover encountered the rock while exploring Neretva Vallis. It is an ancient river valley created when water entered Jezero Crater in the distant past.
As a result, the valley is regarded as a favorable place for uncovering evidence of previous life.
Rock with unique features
The six-wheeled geologist is looking for clues of past microbial life in rocks that may have been formed or modified in water-rich environments.
Cheyava Falls is unlike any rock seen by the rover before — it is brimming with intriguing features.
SHERLOC detected organic or carbon-based molecules that are often linked with life in the rock. SHERLOC is an instrument onboard the rover, which stands for Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals. However, these can also be produced through non-living processes.
The rover first came across the rock’s long white calcium sulfate veins and reddish streaks of hematite. Hematite is one of the minerals that gives Mars its red color.
However, upon closer inspection, Perseverance discovered numerous tiny, off-white circles encircled by black rings that resembled leopard spots. These spots only measure a millimeter in width.
Interestingly, the black rings were found to contain iron and phosphate.
“These spots are a big surprise. On Earth, these types of features in rocks are often associated with the fossilized record of microbes living in the subsurface,” said David Flannery, an astrobiologist and member of the Perseverance science team.
On Earth, chemical processes turn red hematite into white rock with black rings of iron and phosphate. Furthermore, these processes produce energy that can support microbial life.
Further examination required
Could these markings be evidence of ancient Martian life ? The possibility is tantalizing, but scientists caution that other explanations are possible.
One theory is that the rock started as mud rich in organic matter, which solidified over time. Years later, fluids carrying minerals seeped into cracks in the rock, forming calcium veins and distinctive spots.
The presence of olivine in the rock indicates it may have been subjected to intense heat. It potentially created the spots through a chemical process occurring in a previously hot environment unsuitable for life.
“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,” Farley noted in the press release.
Farley added: “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.”
A more in-depth analysis of the rock can be conducted once it’s brought back to Earth.
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