Study rules out existence of life in Martian meteorite

CAPE CAÑAVERAL, Florida, USA (AP) – A 4 billion-year-old meteorite from Mars that caused a stir on Earth decades ago contains no evidence of early Martian life, scientists reported Thursday.

In 1996, a team led by NASA announced that the organic compounds discovered in the meteorite would have apparently been left behind by living creatures. Other scientists were skeptical, and various researchers have been undermining this premise for decades. A team led by Andrew Steele of the Carnegie Institute for Science was the most recent.

Small samples from the meteorite reveal that the carbon-rich compounds are actually the result of water – very possibly salty or brackish – flowing over the rock for an extended period, Steele said. The findings were published in the journal Science.

At the humid origins of Mars, at least two impacts occurred near the rock, warming the surface of the planet around it, before a third impact ejected it from the Martian surface into space millions of years ago. The 2 kilogram (4 pound) rock was found in Antarctica in 1984.

Groundwater that flowed through crevices in the rock, while it was still on Mars, formed the small units of carbon that are present, according to the researchers. The same thing can happen on Earth and could help explain the presence of methane in the Martian atmosphere, they added.

However, two of the scientists who participated in the original study disagreed with the most recent findings, calling them “disappointing.” In a joint email they stated that they defend their 1996 observations.

“While the data presented adds to our knowledge (of the meteorite), the interpretation is hardly novel, nor supported by research,” wrote Kathie Thomas-Keprta and Simon Clemett, astromatter researchers at NASA’s Johnson Space Center. In Houston.

“Unsubstantiated speculation does not help to solve the enigma surrounding the origin of organic matter” in the meteorite, they added.

According to Steele, current technological advances made his team’s new findings easier.

He praised the measurements made by the original researchers and stressed that their hypothesis of existence of life “was a reasonable interpretation” at the time. He said he and his team – which includes scientists from NASA, Germany and Britain – were careful to present their results “for what they are, which is a very exciting discovery about Mars, and not a study to disprove” the premise. original.

This finding “is of enormous importance in understanding how life originated on this planet and helps us to refine the techniques we need to find life in other parts of Mars, or in Enceladus and Europa,” Steele said in a statement, referring to the moons of Saturn and Jupiter that have oceans under their surfaces.

The only way to show whether Mars has or ever had microbial life, according to Steele, is to bring samples back to Earth for analysis. NASA’s Perseverance probe has already collected six samples to send back to Earth in about a decade; the desired quantity is about three dozen samples.

Millions of years after wandering through space, the meteorite fell in Antarctica thousands of years ago. The small gray and green fragment was named Alan Hills 84001, after the hills where it was discovered.

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The Associated Press Department of Health and Science receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.

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