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Ancient Mars is increasingly seen as a dwelling place for life.
The famous Mars meteorite Allan Hills 84001 (ALH84001) contains 4 billion-year-old native organic molecules, the building blocks of life that contain carbon as we know it, a new study suggests.
And that’s not all. Organics contain nitrogen, another ingredient on which life on Earth depends, and were found within carbonate minerals, which generally form in groundwater. So the discovery adds to an emerging image of a wet and potentially habitable Mars in the distant past, study team members said.
Related: Life on Mars: exploration and evidence
This image has been developed by a range of observations over the years, including recent work by NASA’s Mars Curiosity rover. Curiosity has stained from ancient native organic Also, and the car-sized robot found evidence of a long-standing but long-lived lake and stream system at its study site, the 96-mile-wide (154-kilometer) Gale crater of the Red Planet. (Mars is very different today, of course; the planet transitioned to a cold, dry world about 3.5 billion years ago, after it lost most of its atmosphere in space.)
Scientists think that ALH84001 was destroyed on Mars by a powerful impact 16 million years ago and arrived on Earth much later, about 13,000 years ago.
The meteorite, which was discovered in Antarctica in 1984, has been in the spotlight before. In 1996, a research team led by David McKay of NASA’s Johnson Space Center claimed to have found compelling evidence for ancient microbes. Life on Mars at ALH84001. The scientists cited four main lines of evidence, one of which involved carbonate globules and organic molecules.
The scientific community has generally considered this collection of evidence to be unconvincing, and emphasizes that abiotic factors may explain the observations. But the study authors maintain their original conclusions and debate ALH84001. continues to this day.
In the new study, researchers led by Mizuho Koike of the Japan Aerospace Exploration Agency’s Institute for Space Science and Astronautics looked at the rock on Mars in a new way. The team used novel and highly accurate analytical techniques, including a type of X-ray spectroscopy, to detect nitrogen in ALH84001 and trace it back to the carbonate minerals.
This was the first; No one had found nitrogen-containing organics in the rock before, team members said. Researchers think that the organics were trapped in the carbonate about 4 billion years ago; They said their techniques minimized the possibility of terrestrial contamination, which is always a concern with meteorites from Mars.
To be clear: organics are not evidence of life on Mars; Such compounds can be produced both abiotic and biotic. And there are also other important questions about ALH84001 organic compounds, like where they were formed.
“There are two main possibilities: either they came from outside Mars, or they trained on Mars,” co-author of the study Atsuko Kobayashi of the Institute of Earth Life Sciences of the Tokyo Institute of Technology, he said in a statement.
“Early in the history of the solar system, Mars probably received a large amount of organic matter, for example from carbon-rich meteorites, comets and dust particles,” added Kobayashi. “Some of them may have dissolved in the [Martian] brine and trapped inside the carbonates. “
Scientists have an opportunity to make real progress on the question of life on Mars soon. From nasa Mars 2020 rover perseverance, which will launch in July, will look for signs of the ancient organisms of the Red Planet and will collect samples for the future return to Earth. Once this pristine Mars material lands here, which could happen as early as 2031, researchers around the world will be able to analyze it in great detail.
The new study was published online April 24 in the journal. Nature’s Communications.
Mike Wall is the author of “Out there“(Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for extraterrestrial life. Follow him on Twitter @michaeldwall. Follow us on twitter @Spacedotcom or Facebook.
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