by Marcia Dunn | The Associated Press
Cape Canaveral, Fla. A 4-billion-year-old meteorite from Mars that hit Earth here decades ago has no evidence of ancient, primitive Martian life, scientists reported Thursday.
In 1996, a NASA-led team announced that organic compounds in the rock appeared to have been released by living beings. Other scientists were skeptical and researchers have done away with that premise for decades, most recently by a team led by Andrew Steele of the Carnegie Institution for Science.
Steele said small samples of the meteorite suggest that the carbon-rich compounds are actually the result of water — most commonly salty, or sparkling, water — flowing over the rock over a long period of time. The findings appear in the journal Science.
During Mars’ wet and early past, at least two impacts occurred near the rock, before warming the planet’s surrounding surface, a third impact buoyed it from the Red Planet and into space millions of years ago. The 4-pound (2-kg) rock was found in Antarctica in 1984.
According to the researchers, groundwater moving through cracks in the rock, while it was still on Mars, formed tiny globs of carbon. The same could happen on Earth, he said, and could help explain the presence of methane in the Martian atmosphere.
But the two scientists who participated in the original study called them “disappointing” with these latest findings. In a shared email, he said he stood by his 1996 comments.
“While the presented data increase our knowledge of[the meteorite]the interpretation is hardly novel, nor is it supported by research,” wrote astrophysicists Kathy Thomas-Capreta and Simon Klemet of NASA’s Johnson Space Center in Houston.
“The unsupported speculation does nothing to solve the puzzle surrounding the origin of organic matter” in meteorites, he said.
According to Steele, advances in technology made his team’s new findings possible.
He praised the measurement by the original researchers and said that their life-claim hypothesis “was a reasonable explanation” at the time. He said that he and his team – which includes NASA, German and British scientists – took care to present their results “what they are, which is a very exciting discovery about Mars and to disprove the basic premise.” There is no study”.
The discovery is “huge to our understanding of how life began on this planet and helps to refine the techniques we need to find life elsewhere on Mars, or Enceladus and Europa,” Steele said in a statement. Said in the email, referring to the moons of Saturn and Jupiter with subsurface oceans.
According to Steele, the only way to prove whether there was ever microbial life on Mars is to bring samples to Earth for analysis. NASA’s Perseverance Mars rover has collected six samples to return to Earth in a decade or so; three dozen samples desired
Millions of years after drifting into space, the meteorite landed on an ice field in Antarctica thousands of years ago. The small gray-green piece got its name – Allen Hills 84001 – from the hills where it was found.
This week, a fragment of this meteorite was used in the first experiment of its kind on the International Space Station. A mini scanning electron microscope examined the sample; Thomas-Capreta operated it remotely from Houston. Researchers hope to use the microscope to analyze geologic samples in space – for example, one day on the Moon – and debris that could ruin the station’s equipment or endanger astronauts.
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