Case Western Reserve University geologists have urged caution in claiming signs of life on Mars from speckled rock found by Perseverance Rover.
Ralph Harvey believes that a non-biological origin of the speckled rock found on Mars by NASA’s Perseverance Rover is just as compelling as a biological one. The area the rover is exploring likely underwent heating and metamorphosis of rocks and organic materials without involving biological processes, he said. “Earth’s original atmosphere and surface chemistry was enormously hostile to life by today’s standards, but somehow life arose 3.5 billion years ago.”
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“Our planet’s history includes multiple cataclysms that prove that the flexibility inherent in natural selection makes life VERY difficult to kill off, such that biology becomes a driving force that can utterly transform the planet’s atmosphere, surface mineralogy and climate,” Harvey said.
“I find it difficult to accept the hypothesis that Mars had microorganisms making use of reduction reactions for metabolic purposes, but somehow they didn’t become global quickly and lead to the same kinds of complete transformations Earth experienced.”
Martian meteorites
Harvey, professor of Earth, Environmental and Planetary Sciences, is a planetary geologist who specializes in materials like meteorites, moon rocks and earth rocks. He has studied Martian meteorites for many years and helped debunk biological origins for the meteorite ALH84001 in the 1990s. He was one of the first to suggest that Jezero crater on Mars would be a good place to explore, which is where NASA’s Perseverance Rover is now.
Albert Colman, associate professor of Earth Environmental and Planetary Sciences agrees, though he expressed more optimism that there could have been a biological origin.
On Earth, the variations in composition and patterns in mineralogy might be interpreted as having resulted from microbial activity if they were found in sedimentary rocks less than 2 billion years old, Colman said. “However, there may be ways to generate some or possibly even all of these same patterns through abiological processes.”
“If these sediments were exposed to hydrothermal fluids for long periods of time, some of the same reactions that we find to be biologically mediated on Earth could potentially have occurred in the absence of biology.”
Cutting edge tools
Colman added, “Analysis with cutting edge tools in geoscience labs on Earth would almost certainly answer the question of whether or not these rocks hold evidence for past life on Mars.
“This is a valuable paper, and the authors have presented a plausible scenario for biological production of these observed patterns in chemistry and mineralogy,” Colman said. “The researchers were appropriately cautious in their conclusions. This is definitely not proof of past life on Mars. I am sure they are itching to have samples of these rocks brought back to Earth to analyze with a range of instruments that just isn’t practical to include on a rover.”
Colman is a biogeochemist who studies microbial activity and chemical cycling in modern, sometimes extreme terrestrial environments to learn more about what microbial life might have been like on the early Earth and on other planets.
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