It will take a lot more work to find out if the compounds found on the Red Planet are signs of ancient Mars life.
Some of the powdered rock samples collected over the years contain organics rich in a type of carbon that is associated with life, according to a new study.
Mars is very different from our world, and many of the processes there are still unknown. It's too early to know what caused the intriguing chemicals, study team members stressed.
"We're finding things on Mars that are intriguing, but we would really need more evidence to say we've identified life," said Paul Mahaffy, who retired from NASA. We're looking at what else could have caused the carbon signature.
NASA's rover on Mars has amazing photos.
The mosaic was made from images taken by the Mast Camera on the Mars rover. The landscape of the Stimson sandstone formation is shown. The sample from the Edinburgh drill hole was enriched in carbon 12. The image is from NASA/Caltech-JPL/MSSS.
In August of 2012 the rover was sent to Mars to determine if the area could ever have supported life. A lake-and-stream system that likely persisted for millions of years at a time was discovered by the rover team.
The research team looked at two dozen powdered rock samples that were collected with the drill from a variety of locations between August 2012 and July 2021. The SAM can identify and characterization organics, which are carbon-containing molecules that are the building blocks of life on Earth.
The scientists found that carbon-12, the lightest of the two stable carbon isotopes, was enriched in nearly half of the samples. Isotopes are versions of elements that have different numbers of neutrons in their atomic nuclei. The less abundant carbon-13 has seven of the six neutrons.
The samples were from five different locations within the crater, all of which had ancient surfaces that had been preserved well over the eons.
In ancient rock samples here, carbon-12 enrichment is seen as a signal of biotic chemistry because organisms preferentially use carbon-12 for their metabolism. Study team members said that carbon cycles on Mars aren't well understood enough to make similar assumptions for Red Planet.
There are three possible explanations for the carbon signal. The first involves Mars microbes producing methane, which was then converted into more complex organic molecules after interacting with UV light in the Red Planet air. The larger organics fell back to the ground and were incorporated into the rocks.
The most abundant gas in Mars' atmosphere, carbon dioxide, could have been generated by similar reactions. The researchers said it's possible that the solar system went through a giant cloud of carbon-12 long ago.
The study leader said that all three explanations fit the data. We need more data to rule them out.
Life on Mars: exploration and evidence.
More data is needed.
The new find is intriguing because of the carbon-12 enrichment, but the previous detection of organic compounds on Mars is still intriguing. The mission team previously reported the detection of organics in powdered rock samples. Methane, the simplest organic molecule, has been driven through by the six-wheeled robot.
It's not clear what's making Mars' methane or how old it is. The compound may be created by the metabolism of the microbes beneath the surface of Mars. It could be produced by underground interactions of rock and hot water. It could be ancient material that was trapped underground long ago and occasionally "burps" up onto the surface today.
The team of the Curiosity team would love to drive through another methane plume and determine its carbon-12 content. It would take a lot of luck, because researchers can't predict when and where the plumes will appear.
Perseverance, a NASA robot that landed inside a different Red Planet crater in February 2021, could provide further helpful data. Perseverance is hunting for signs of ancient Mars life and collecting dozens of samples that will be returned to Earth for analysis.
" Out There" is a book about the search for alien life and was illustrated by Karl Tate. You can follow him on the social networking site. Follow us on social media.
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