NASA’s Curiosity Rover Measures Gravitational Carbon Sign On Mars – Would You Stand Out for That?
After analyzing powdery rock samples collected from the Martian surface by NASA’s Curiosity rover, scientists today announced that some samples are rich in a type of carbon that is involved in chemical processes. biology on Earth.
While the finding is intriguing, it doesn’t necessarily point to ancient life on Mars, as scientists have yet to find convincing supporting evidence of ancient or current biology there. such as sedimentary rock formations produced by ancient bacteria, or a variety of complex organic matter. molecules created by life.
“We’re finding interesting stuff on Mars, but we really need more evidence to say we’ve identified life,” he said. Paul Mahaffy, who was the principal investigator of Analysis of samples at Mars Chemical Laboratory (SAM) on board Curiosity until retiring at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, in December 2021. “So we were looking at what else could be there. could cause the carbon signatures we’re seeing, if not life.”
This image shows the Highfield borehole performed by NASA’s Curiosity rover while it was collecting samples on Vera Rubin Ridge in Gale Crater on Mars. Powder drilled from this borehole has been enriched with carbon 12. The image was taken by the Mars Hand Lens Imager on Mars day 2,247, or the second day of the mission. Vendor: NASA/Caltech-JPL/MSSS.
In a report on their findings published in the journal Proceedings of the National Academy of Sciences on January 18, the Curiosity scientists offer several explanations for the unusual carbon signals they detectable. Their theories are partly drawn from Earth’s carbon symbols, but the scientists warn the two planets are so different they can’t draw precise conclusions based on examples of Earth soil.
“The hardest thing is to let go of the Earth and let go of the prejudices that we have and really try to get into the fundamentals of chemical, physical, and environmental processes on Mars,” astronomer Goddard said Jennifer L. Eigenbrode, who has been involved in carbon research. Previously, Eigenbrode led an international team of Curiosity scientists in detect countless organic molecules – things that contain carbon – on the surface of Mars.
“We need to open our minds and think outside the box,” says Eigenbrode, “and that is what this paper does.”
The biological explanation Curiosity scientists present in their paper is inspired by life on Earth. It involves ancient bacteria on the surface that can produce a single carbon signature when they release methane into the atmosphere, where ultraviolet light converts that gas into larger molecules. , more complex. These new molecules will fall to the surface and can now be preserved with their distinct carbon signature in the Martian rock.
Two other hypotheses offer abiotic explanations. One suggested that the carbon signature could be the result of ultraviolet light’s interaction with carbon dioxide in the Martian atmosphere, creating new carbon-containing molecules that could settle to the surface. And others speculate that the carbon may have been left behind after a rare event hundreds of millions of years ago when the solar system passed through a giant molecular cloud rich in the type of carbon discovered.
“All three explanations are consistent with the data,” said Christopher’s House, a Penn State-based Curiosity scientist who led the carbon study. “We simply need more data to remove them.”
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To analyze the carbon on the Martian surface, House’s team used Adjustable laser spectrometer (TLS) inside the SAM lab. SAM heated 24 samples from geologically diverse locations in the planet’s Gale crater to about 1,500 degrees Fahrenheit, or 850 degrees Celsius, to release the gases inside. The TLS then measures isotopes from some of the reduced carbons released freely during heating. Isotopes are atoms of an element that differ in mass because of their distinct number of neutrons, and they are instrumental in understanding the chemical and biological evolution of planets.
Carbon is especially important because it is found in all life on Earth; it flows continuously through the air, water and ground in a cycle well understood by isotope measurements.
For example, organisms living on Earth use the smaller, lighter carbon 12 atom to metabolize food or to photosynthesize than the heavier carbon 13 atom. Therefore, the amount of carbon 12 is significantly more than carbon 13 in ancient rocks, along with other evidence, suggesting that scientists are looking at signs of the chemistry associated with life. Looking at the ratio of these two carbon isotopes helps Earth scientists understand the type of life they are looking at and the environment it lives in.
On Mars, the Curiosity researchers found that nearly half of their samples had a surprisingly large amount of carbon 12 compared to what scientists measured in the Martian atmosphere and meteorites. These samples came from five different sites in Gale Crater, the researchers report, which may be related to the fact that all sites have well-preserved ancient surfaces.
“On Earth, the processes that generate the carbon signals that we’re detecting on Mars are biological,” House said. “We have to understand whether the same explanation holds for Mars or there are other explanations, because Mars is so different.”
Mars is unique because it probably started with a different mixture of carbon isotopes than Earth 4.5 billion years ago. Mars is smaller, cooler, has weaker gravity, and different gases in its atmosphere. Alternatively, the carbon on Mars may be spinning without any life involved.
“There’s a big part of the carbon cycle on Earth that’s related to life, and for life, there’s a part of the carbon cycle on Earth that we just can’t understand, because everywhere we look there’s life. ,” speak Andrew Steele, a Curiosity scientist based at the Carnegie Institution for Science in Washington, DC
This mosaic was created from images taken by Mast Camera aboard NASA’s Curiosity rover on Mars day 2,729, or sol day, of the mission. It shows the landscape of the Stimson sandstone formation in Gale Crater. At this joint site, Curiosity drilled the Edinburgh borehole, a sample from which is enriched with carbon 12. Supplier: NASA/Caltech-JPL/MSSS
Steele notes that scientists are in the early stages of understanding how carbon cycles on Mars and, therefore, how to interpret isotope ratios and the abiotic activities that might lead to those ratios. . Curiosity, which arrived on the Red Planet in 2012, was the first rover with the tools to study carbon isotopes on the surface. Other missions have collected information about isotope signatures in the atmosphere, and scientists have measured the proportion of Martian meteorites collected on Earth.
“Determining the carbon cycle on Mars is absolutely key to trying to understand how life might fit into that cycle,” says Steele. “We’ve done that really successfully on Earth, but we’re just starting to define that cycle for Mars.”
Curiosity scientists will continue to measure the carbon isotopes to see if they pick up similar signatures when the explorer visits other sites suspected to have well-preserved ancient surfaces. To further test the biological hypothesis regarding methane-producing microorganisms, the Curiosity team wanted to analyze the carbon content of a plume of methane escaping from the surface. Explorers encountered such a situation unexpectedly in 2019 but there is no way to predict whether it will happen again. On the other hand, the researchers point out that this study provides guidance for the team behind NASA Endurance Probe about the best types of samples to collect to confirm the carbon signature and determine with certainty whether it comes from life. Perseverance is collecting samples from the surface of Mars to may return to Earth in the future.
Curiosity’s mission is led by NASA’s Jet Propulsion Laboratory in Southern California; JPL is managed by Caltech.Banner image: NASA’s Curiosity rover captured these clouds shortly after sunset on March 19, 2021, Mars’ 3,063th day, aka day one, of its mission the Explorer. The image is made up of 21 individual images that are stitched together and color corrected to make the scene look like the human eye. Vendor: NASA / JPL-Caltech / MSSS
Via Lonnie Shekhtman
NASA’s Goddard Space Flight Center, Greenbelt, Md. Last Updated: January 18, 2022 Editor: Svetlana Shekhtman
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