Scientists have concluded that a meteorite from Mars contains no evidence of ancient Martian life
CAPE CANAVERAL, Florida – A 4-billion-year-old meteorite from Mars that spewed a streak here on Earth decades ago contains no evidence of ancient primitive life on Mars, scientists reported Thursday.
In 1996, a NASA-led team announced that organic compounds in the rock had been left by living organisms. Other scientists have been skeptical and researchers have debunked this hypothesis for decades, most recently a team led by Andrew Steele of the Carnegie Institution for Science.
Steele said small samples of the meteorite show that the carbon-rich compounds are actually the result of water — salty or likely salty water — that has been flowing over the rock for a long time. The results appear in the journal Science.
During Mars’ wet period and early past, at least two impacts occurred near the rocks, warming the planet’s surrounding surface, before a third impact bounced off the Red Planet into space millions of years ago. The 4 pound (2 kilogram) rock was found in Antarctica in 1984.
According to the researchers, the groundwater moving through cracks in the rock, while it was still on the surface of Mars, formed the tiny balls of carbon that are present. They said the same could happen on Earth and could help explain the presence of methane in Mars’ atmosphere.
But two of the scientists who took part in the original study disputed these latest findings, calling them “disappointing.”
“While the data presented gradually adds to our (meteor) knowledge, the explanation is not new, and is not supported by research,” wrote Kathy Thomas Kiberta and Simon Klimt, astronomical materials researchers at NASA’s Johnson Space Center in Houston.
They added that “unsupported speculation does nothing to solve the mystery surrounding the origin of the organic matter” in the meteorite.
According to Steele, technological advances made his team’s new discoveries possible.
He praised the measurements made by the original researchers, and noted that the life-claim hypothesis was a “reasonable explanation” at the time. He said that he and his team – which includes NASA scientists, German and British scientists – were interested in presenting their results “for what they are, a very exciting discovery about Mars rather than a study to disprove” the original hypothesis.
Steele said in an email, referring to the subterranean oceans of the moons of Saturn and Jupiter.
According to Steele, the only way to establish whether Mars has microbial life or still exists, is to bring samples back to Earth for analysis. NASA’s Perseverance probe on Mars has collected six samples to bring back to Earth within a decade or so; Three dozen samples are required.
After millions of years of drifting through space, the meteorite landed on an ice field in Antarctica thousands of years ago. The small, gray-green lot got its name – Allan Hills 84001 – from the hills in which it was found.
Just this week, a piece of this meteorite was used in a first-of-its-kind experiment aboard the International Space Station. Examination of a small sample scanning electron microscope; Thomas-Keprta worked as remotely operated from Houston. The researchers hope to use the microscope to analyze geological samples in space — on the moon one day, for example — and debris that could destroy station equipment or endanger astronauts.
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