NASA’s Curiosity rover has found interesting organic compounds on the Red Planet that could be signs of ancient Mars life, but much more work will be needed to test this hypothesis.
Some of the powdered rock samples that Curiousity has collected over the years contains organic material rich in a type of carbon that here on Earth is associated with life, researchers report in a new study.
Corn March is very different from our world, and many Martian processes remain mysterious. It is therefore too early to know what generated these intriguing chemicals, the study team members pointed out.
“We’re finding things on Mars that are extremely interesting, but we really need more evidence to say we’ve identified life,” said Paul Mahaffy, who served as the principal investigator at the Curiosity chemistry lab’s Sample Analysis. at Mars (SAM) until retiring from NASA’s Goddard Space Flight Center in Greenbelt, Maryland in December 2021, said in a press release. “So we’re looking at what could have caused the carbon signature we’re seeing, if not life.”
Related: Stunning photos of Mars taken by NASA’s Curiosity rover
Nearly a decade of sample analysis
Curiosity landed inside Mars, 96 miles (154 kilometers) wide wind crater in August 2012 as part of a mission to determine if the area could have supported microbial life. The rover team quickly determined that the Gale floor was a potentially habitable environment billions of years ago, supporting a system of lakes and streams that likely persisted for millions of years at a time.
In the new study, to be published Tuesday, Jan. 18, in the Proceedings of the National Academy of Sciences, the research team examined two dozen samples of powdered rock that Curiosity collected with its hammer drill from various locations. between August 2012 and July 2021. The rover fed this material into SAM, which can identify and characterize organic matter – carbon-containing molecules that are the building blocks of life on Earth.
Scientists found that almost half of these samples were enriched in carbon-12, the lighter of the two stable isotopes of carbon, compared to previous measurements of meteorites from Mars and the Earth. Martian atmosphere. (Isotopes are versions of an element that contain different numbers of neutrons in their atomic nuclei. Carbon-12 has six neutrons, and the much less abundant carbon-13 has seven.)
These high-carbon-12 samples came from five different locations in Gale Crater, all of which exhibited ancient surfaces that had been well-preserved over eons.
On Earth, organisms preferentially use carbon-12 for their metabolic processes, so the enrichment of this isotope in ancient rock samples is generally interpreted here as a signal of biotic chemistry. But the carbon cycles on Mars aren’t well enough understood to make similar assumptions for the Red Planet findings, study team members said.
The researchers offered three possible explanations for the intriguing carbon signal. The first involves microbes from Mars producing methane, which was then converted into more complex organic molecules after interacting with ultraviolet (UV) light in the Red Planet’s air. These larger organic materials then fell to the ground and were incorporated into the rocks sampled by Curiosity.
But similar reactions involving UV light and non-biological carbon dioxide, by far the most abundant gas in Mars’ atmosphere, could also have generated the result. It’s also possible that the solar system drifted through a giant carbon-12-rich molecular cloud a long time ago, the researchers said.
“All three explanations fit the data,” study leader Christopher House, a Curiosity scientist based at Penn State University, said in the same statement. “We just need more data to rule them out or rule them out.”
Related: Life on Mars: Exploration and Evidence
More data needed
The new discovery is particularly intriguing because of carbon-12 enrichment, but Curiosity has already detected organic compounds on Mars. For example, the mission team previously reported the detection of organic matter in powdered rock samples. The six-wheeled robot also has driven through methane plumes, the simplest organic molecule, repeatedly.
It is not known what produces Mars’ methane gas or its age. For example, the compound may be generated by microbes that are actively metabolizing beneath the frigid surface of Mars today. It could alternatively be produced by underground interactions of rock and hot water, with no life involved. It could also be ancient material, produced either by organisms or abiotically, that was trapped underground long ago and occasionally “burps” on the surface today.
The Curiosity team would like to walk through another methane plume and determine its carbon-12 content, further exploring the origins of these organic materials. But that would take a lot of luck, since researchers can’t predict when and where such plumes will appear.
Other useful data could also come from another Mars rover – Perseverance, a NASA robot that landed inside another crater on the Red Planet in February 2021. Perseverance is searching Mars for signs of life and collecting dozens of samples that will be sent back to Earth for analysis, may -be from 2031.
Mike Wall is the author of “The low(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 on Facebook.