Latest news with #CarolineFreissinet
RNZ News
18-05-2025
- Science
- RNZ News
Claims of alien life 'fatally flawed'
Caroline Freissinet. Photo: Supplied / Caroline Freissinet Headlines last month captured global excitement after astronomers claimed they detected the "strongest evidence to date" of life on another planet, but a world-leading astrobiologist says the science behind the claim is "fatally flawed". However, one of the scientists behind the claims is standing behind their work. In April, a team from Cambridge claimed to have recorded a possible biosignature, or signs of past or present life linked to biological activity, on an exoplanet named K2-18b. Using the James Webb Space Telescope, the team detected chemical fingerprints that suggest the presence of dimethyl sulphide (DMS) and dimethyl disulphide (DMDS), molecules that on Earth are only produced by microbial life. Carolyn Freissinet is a leading astrobiologist at the French National Center for Scientific Research. She told RNZ's Saturday Morning she believed the claims made by the Cambridge researchers were premature - and potentially misleading. Freissinet, who collaborates with NASA and leads studies of Martian samples collected by the Curiosity rover, said the science behind the announcement simply did not stack up. "This finding is super controversial," she said. "It's not based on a very serious scientific study. It has fatal flaws in the method that has been used." According to Freissinet, just a week after the initial announcement, another team reviewed the same spectral data and found no trace of DMS at all. "So first, there's a problem with the measurement itself." Even if DMS was detected, she said, we shouldn't jump to the conclusion that it's a biosignature. "We understand very poorly the sulphur chemistry of exoplanet atmospheres. There is this famous quote by Carl Sagan. He said that extraordinary claims, such as finding life, require extraordinary evidence." One of the study's authors however said Freissinet's understanding of the findings was "clearly incorrect". Nikku Madhusudhan, professor of astrophysics and exoplanetary science at the Institute of Astronomy, University of Cambridge, told RNZ their study was "the most advanced analysis conducted for an exoplanet with this [James Webb Space Telescope] instrument, and reported the first mid-infrared atmospheric spectrum of a potentially habitable planet outside the solar system ever". "This is a major advancement in the field." He said claims no other teams had detected molecules suggesting evidence of biological processes were also incorrect. "None of them claim that the gases we reported cannot be found. The first study they mentioned, that came a week after ours, was a preliminary analysis which didn't even look for the gases so no conclusive statement can be drawn from it regarding our findings. "The second and third papers which used more realistic models confirmed our calculations and suggested additional gases that could provide alternate explanations to at least some of the data. Our original suggestion of the gas DMS is still the most favoured at this point, considering all available data." Freissinet did not dismiss the search for extraterrestrial life - it was the core of her work. But she argued that the search must be methodical, rigorous, and grounded in evidence. "Right now, we're accumulating hints... pieces of a puzzle." Some of those puzzle pieces are found on Mars. In 2013, Freissinet and her team also made headlines with the discovery of long-chain hydrocarbons in 3.7-billion-year-old Martian rocks at a site called Cumberland. These molecules, made up of ten or more carbon atoms, are incredibly fragile, especially on Mars, where conditions are harsh and preservation is rare. "What we can say now is that if life ever existed on Mars... we could find those traces of life." But she's careful not to overstate the findings. "It's definitely not hints of life," she clarified. "We cannot tell if the origin of the molecules if they are biological or if they are pure chemical reactions." So what would "life" look like? Freissinet emphasised just how difficult it was to identify alien life, especially when we only have one known example - Earth. "We try to identify life as we don't know it," she said. "It's really hard." One method scientists use is to look for chemical imbalances that suggest biological processes. For example, amino acids, the building blocks of proteins, exist in two mirror-image forms. On Earth, life uses only one of these forms. A similar imbalance found elsewhere could be a clue. Still, even these signs require cautious interpretation. Natural processes can sometimes mimic the patterns life creates. At the Cumberland site, Freissinet's team also found traces of nitrates and lighter isotopes of carbon and sulphur elements, which, on Earth, were often associated with biological activity. But even these, she said, had potential non-biological explanations. Madhusudhan said there was "usually a lot of debate" around the subject, but urged people "not to confuse debate with misinformation". Freissinet's perspective was not one of scepticism, but of scientific integrity. She said discovering evidence of life beyond Earth would likely be a long, slow process and should not take the form of rushed conclusions or overhyped discoveries. "For now, we're we are very far from biosignature detection. We are accumulating hints everywhere in the solar system and elsewhere in the universe, looking at exoplanets to make a story. "We're accumulating pieces of a puzzle. And one day, hopefully, this puzzle will assemble." Sign up for Ngā Pitopito Kōrero, a daily newsletter curated by our editors and delivered straight to your inbox every weekday.
Yahoo
19-04-2025
- Science
- Yahoo
Curiosity rover finds largest carbon chains on Mars from 3.7-billion-year-old rock
When you buy through links on our articles, Future and its syndication partners may earn a commission. The longest molecules ever found on Mars have been unearthed by NASA's Curiosity rover, and they could mean the planet is strewn with evidence for ancient life. Molecule chains containing up to twelve carbon atoms linked together were detected in a 3.7 billion-year-old rock sample collected from a dried-up Martian lakebed named Yellowknife Bay, according to a study published March 24 in the journal Proceedings of the National Academy of Sciences. These long carbon chains are thought to have originated from molecules called fatty acids, which, on Earth, are produced by biological activity. While fatty acids can form without biological input, which may be the case on Mars, their existence on the Red Planet means that signs of life may be lurking within its soil. "The fact that fragile linear molecules are still present at Mars' surface 3.7 billion years after their formation allows us to make a new statement: If life ever appeared on Mars billions of years ago, at the time life appeared on the Earth, chemical traces of this ancient life could still be present today for us to detect," study co-author Caroline Freissinet, an analytical chemist at the French National Centre for Scientific Research in the Laboratory for Atmospheres and Space Observations, told Live Science. The molecules — hydrocarbon strings of 10, 11 and 12 carbon atoms called decane, undecane, and dodecane — were detected by Curiosity's Sample Analysis at Mars (SAM) instrument. The Curiosity Rover arrived on Mars in 2012 at the Gale Crater, a massive 96-mile-wide (154 km-wide) impact crater formed by the planet's collision with an ancient meteorite. In the years since, the rover has traveled about 20 miles (32 km) across the crater, investigating places including Yellowknife Bay and Mount Sharp (Aeolis Mons), a 3.4-mile-high (5.5 km-high) mountain in the center of the crater. Related: NASA Mars rover finds 'first compelling detection' of potential fossilized life on the Red Planet Nicknamed "Cumberland", the sample analyzed for the new study was drilled by Curiosity in 2013 from Yellowknife Bay, and previous analyses found it to be rich in clay minerals, sulfur, and nitrates. But despite many thorough tests, the hydrocarbon strings in the sample remained undetected for more than a decade. The hydrocarbons were actually discovered by accident as part of an attempt to find the building blocks of proteins — known as amino acids — in the sample. The researchers behind the new study thought to test out a new method for finding these molecules by pre-heating the sample to 1,100°C (2,012°F) to release oxygen before analysis. Their results showed no amino acids, but, by pure luck, they discovered the fatty molecules hiding there instead. "The excitement was super high when I saw the peaks on the spectrum for the first time," Freissinet said. "It was both surprising and not surprising. Surprising because those results were found on the Cumberland sample that we had already analyzed many times in the past. Not surprising because we have defined a new strategy to analyze this sample." "New method, new results," she added. The researchers suggest that the molecules may have broken off from the long tails of fatty acids named undecanoic acid, dodecanoic acid, and tridecanoic acid, respectively. Fatty acids are long chains of carbon and hydrogen with a carboxyl (-COOH) acid group at the end. To test this theory, the researchers mixed undecanoic acid into a Mars-like clay in the lab before performing a test similar to that carried out by the SAM instrument As expected, the undecanoic acid broke down to decane, indicating that the carbon chains could indeed have originated from fatty acids. On Earth, molecules like these are overwhelmingly produced by biological processes, but they can also occur naturally without life. However, non-biological processes usually only result in fatty acids with fewer than 12 carbon atoms, the researchers say. While the longest carbon chain detected by SAM had 12 carbons, the instrument is not optimized to detect longer molecules, meaning that it is possible longer chains were also present. RELATED STORIES —NASA may have unknowingly found and killed alien life on Mars 50 years ago, scientist claims —'Building blocks of life' discovered on Mars in 10 different rock samples —Just 22 people are needed to colonize Mars — as long as they are the right personality type, study claims "There is evidence that liquid water existed in Gale Crater for millions of years and probably much longer, which means there was enough time for life-forming chemistry to happen in these crater-lake environments on Mars," study co-author Daniel Glavin, a researcher at NASA's Goddard Space Flight Center, said in a NASA statement. Regardless of what made them, the detection of the carbon chains and their likely origins as fatty acids confirms that Curiosity can detect molecules of this kind, and that the molecules can remain preserved for billions of years in the Martian environment. The researchers hope to one day bring samples of Martian soil back home to Earth to properly analyze the contents, and hopefully solve the mystery of the Red Planet's elusive life once and for all. "We are ready to take the next big step and bring Mars samples home to our labs to settle the debate about life on Mars," said Glavin. This article was originally published on March 25, 2025
CNN
29-03-2025
- Science
- CNN
Curiosity rover makes ‘arguably the most exciting organic detection to date on Mars'
The NASA Curiosity rover has detected the largest organic molecules found to date on Mars, opening a window into the red planet's past. The newly detected compounds suggest complex organic chemistry may have occurred in the planet's past — the kind necessary for the origin of life, according to new research. The organic compounds, which include decane, undecane and dodecane, came to light after the rover analyzed a pulverized 3.7 billion-year-old rock sample using its onboard mini lab called SAM, short for Sample Analysis at Mars. Scientists believe the long chains of molecules could be fragments of fatty acids, which are organic molecules that are chemical building blocks of life on Earth and help form cell membranes. But such compounds can also be formed without the presence of life, created when water interacts with minerals in hydrothermal vents. The molecules cannot currently be confirmed as evidence of past life on the red planet, but they add to the growing list of compounds that robotic explorers have discovered on Mars in recent years. A study detailing the findings was published Monday in the journal Proceedings of the National Academy of Sciences. The detection of the fragile molecules also encourages astrobiologists that if any biosignatures, or past signs of life, ever existed on Mars, they are likely still detectable despite the harsh solar radiation that has bombarded the planet for tens of millions of years. 'Ancient life, if it happened on Mars, it would have released some complex and fragile molecules,' said lead study author Dr. Caroline Freissinet, research scientist at the French National Centre for Scientific Research in the Laboratory for Atmospheres, Observations, and Space in Guyancourt, France. 'And because now we know that Mars can preserve these complex and fragile molecules, it means that we could detect ancient life on Mars.' The finding also adds fuel to the fire to return samples from Mars so scientists can study them on Earth with more sophisticated tools, and perhaps, once and for all, determine whether life ever existed anywhere beyond our planet. Curiosity landed in Gale Crater on August 6, 2012. More than 12 years later, the rover has driven over 21 miles (34 kilometers) to ascend Mount Sharp, which is within the crater. The feature's many layers preserve millions of years of geological history on Mars, showing how it shifted from a wet to a dry environment. Perhaps one of the most valuable samples Curiosity has gathered on its mission to understand whether Mars was ever habitable was collected in May 2013. The rover drilled the Cumberland sample from an area within a crater called Yellowknife Bay, which resembled an ancient lake bed. The rocks from Yellowknife Bay so intrigued Curiosity's science team that it had the rover drive in the opposite direction to collect samples from the area before heading to Mount Sharp. Since collecting the Cumberland sample, Curiosity has used SAM to study it in a variety of ways, revealing that Yellowknife Bay was once the site of an ancient lake where clay minerals formed in water. The mudstone created an environment that could concentrate and preserve organic molecules and trapped them inside the fine grains of the sedimentary rock. Freissinet helped lead a research team in 2015 that was able to identify organic molecules within the Cumberland sample. The instrument detected an abundance of sulfur, which can be used to preserve organic molecules; nitrates, which are essential for plant and animal health on Earth; and methane composed of a type of carbon associated with biological processes on Earth. 'There is evidence that liquid water existed in Gale Crater for millions of years and probably much longer, which means there was enough time for life-forming chemistry to happen in these crater-lake environments on Mars,' said study coauthor Daniel Glavin, senior scientist for sample return at NASA's Goddard Space Flight Center in Greenbelt, Maryland, in a statement. Curiosity has maintained pristine pieces of the Cumberland sample in a 'doggy bag' so that the team could have the rover revisit it later, even miles away from the site where it was collected. The team developed and tested innovative methods in its lab on Earth before sending messages to the rover to try experiments on the sample. In a quest to see whether amino acids, the building blocks of proteins, existed in the sample, the team instructed the rover to heat up the sample twice within SAM's oven. When it measured the mass of the molecules released during heating, there weren't any amino acids, but they found something entirely unexpected. The team was surprised to detect small amounts of decane, undecane and dodecane, so it had to conduct a reverse experiment on Earth to determine whether these organic compounds were the remnants of the fatty acids undecanoic acid, dodecanoic acid and tridecanoic acid, respectively. The scientists mixed undecanoic acid into a clay similar to what exists on Mars and heated it up in a way that mimicked conditions within SAM's oven. The undecanoic acid released decane, just like what Curiosity detected. Each fatty acid remnant detected by Curiosity was made with a long chain of 11 to 13 carbon atoms. Previous molecules detected on Mars were smaller, meaning their atomic weight was less than the molecules found in the new study, and simpler. 'It's notable that non-biological processes typically make shorter fatty acids, with less than 12 carbons,' said study coauthor Dr. Amy Williams, associate professor of geology at the University of Florida and assistant director of the Astraeus Space Institute, in an email. 'Larger and more complex molecules are likely what are required for an origin of life, if it ever occurred on Mars.' While the Cumberland sample may contain longer chains of fatty acids, SAM is not designed to detect them. But SAM's ability to spot these larger molecules suggests it could detect similar chemical signatures of past life on Mars if they're present, Williams said. 'Curiosity is not a life detection mission,' Freissinet said. 'Curiosity is a habitability detection mission to know if all the conditions were right … for life to evolve. Having these results, it's really at the edge of the capabilities of Curiosity, and it's even maybe better than what we had expected from this mission.' Before sending missions to Mars, scientists didn't think organic molecules would be found on the red planet because of the intensity of radiation Mars has long endured, Glavin said. Curiosity won't return to Yellowknife Bay during its mission, but there are still pristine pieces of the Cumberland sample aboard. Next, the team wants to design a new experiment to see what it can detect. If the team can identify similar long-chain molecules, it would mark another step forward that might help researchers determine their origins, Freissinet said. 'That's the most precious sample we have on board … waiting for us to run the perfect experiment on it,' she said. 'It holds secrets, and we need to decipher the secrets.' Briony Horgan, coinvestigator on the Perseverance rover mission and professor of planetary science at Purdue University in West Lafayette, Indiana, called the detection 'a big win for the whole team.' Horgan was not involved the study. 'This detection really confirms our hopes that sediments laid down in ancient watery environments on Mars could preserve a treasure trove of organic molecules that can tell us about everything from prebiotic processes and pathways for the origin of life, to potential biosignatures from ancient organisms,' Horgan said. Dr. Ben K.D. Pearce, assistant professor in Purdue's department of Earth, atmospheric, and planetary sciences and leader of the Laboratory for Origins and Astrobiology Research, called the findings 'arguably the most exciting organic detection to date on Mars.' Pearce did not participate in the research. Some scientists believe that fatty acids such as decanoic acid and dodecanoic acid formed the membranes of the first simple cell-like structures on Earth, Pearce said. '(This is) the closest we've come to detecting a major biomolecule-related signal — something potentially tied to membrane structure, which is a key feature of life,' Pearce said via email. 'Organics on their own are intriguing, but not evidence of life. In contrast, biomolecules like membranes, amino acids, nucleotides, and sugars are central components of biology as we know it, and finding any of them would be groundbreaking (we haven't yet).' The European Space Agency plans to launch its ExoMars Rosalind Franklin rover to the red planet in 2028, and the robotic explorer will carry a complementary instrument to SAM. The rover LS6 will have the capability to drill up to 6.5 feet (2 meters) beneath the Martian surface — and perhaps find larger and better-preserved organic molecules. While Curiosity's samples can't be studied on Earth, the Perseverance rover has actively been collecting samples from Jezero Crater, the site of an ancient lake and river delta, all with the intention of returning them to Earth in the 2030s via a complicated symphony of missions called Mars Sample Return. Both rovers have detected a variety of organic carbon molecules in different regions on Mars, suggesting that organic carbon is common on the red planet, Williams said. While Curiosity and Perseverance have proven they can detect organic matter, their instruments can't definitively determine all the answers about their origins, said Dr. Ashley Murphy, postdoctoral research scientist at the Planetary Science Institute. Murphy, who along with Williams previously studied organics identified by Perseverance, was not involved in the new research. 'To appropriately probe the biosignature question, these samples require high-resolution and high-sensitivity analyses in terrestrial labs, which can be facilitated by the return of these samples to Earth,' Murphy said. If the molecules within the Cumberland sample are the byproduct of microbial life that existed 3.7 billion years ago, such a finding would align with the same time frame as when scientists think life was starting on Earth, Glavin said. Curiosity's finding feels 'so close' to helping make that determination, but the answers are more likely to come from studying samples on Earth, he said. 'I'm more optimistic that we're going to finally be able to settle this life on Mars debate, which feels like it's been going on forever,' Glavin said.
CNN
29-03-2025
- Science
- CNN
Curiosity rover makes ‘arguably the most exciting organic detection to date on Mars'
The NASA Curiosity rover has detected the largest organic molecules found to date on Mars, opening a window into the red planet's past. The newly detected compounds suggest complex organic chemistry may have occurred in the planet's past — the kind necessary for the origin of life, according to new research. The organic compounds, which include decane, undecane and dodecane, came to light after the rover analyzed a pulverized 3.7 billion-year-old rock sample using its onboard mini lab called SAM, short for Sample Analysis at Mars. Scientists believe the long chains of molecules could be fragments of fatty acids, which are organic molecules that are chemical building blocks of life on Earth and help form cell membranes. But such compounds can also be formed without the presence of life, created when water interacts with minerals in hydrothermal vents. The molecules cannot currently be confirmed as evidence of past life on the red planet, but they add to the growing list of compounds that robotic explorers have discovered on Mars in recent years. A study detailing the findings was published Monday in the journal Proceedings of the National Academy of Sciences. The detection of the fragile molecules also encourages astrobiologists that if any biosignatures, or past signs of life, ever existed on Mars, they are likely still detectable despite the harsh solar radiation that has bombarded the planet for tens of millions of years. 'Ancient life, if it happened on Mars, it would have released some complex and fragile molecules,' said lead study author Dr. Caroline Freissinet, research scientist at the French National Centre for Scientific Research in the Laboratory for Atmospheres, Observations, and Space in Guyancourt, France. 'And because now we know that Mars can preserve these complex and fragile molecules, it means that we could detect ancient life on Mars.' The finding also adds fuel to the fire to return samples from Mars so scientists can study them on Earth with more sophisticated tools, and perhaps, once and for all, determine whether life ever existed anywhere beyond our planet. Curiosity landed in Gale Crater on August 6, 2012. More than 12 years later, the rover has driven over 21 miles (34 kilometers) to ascend Mount Sharp, which is within the crater. The feature's many layers preserve millions of years of geological history on Mars, showing how it shifted from a wet to a dry environment. Perhaps one of the most valuable samples Curiosity has gathered on its mission to understand whether Mars was ever habitable was collected in May 2013. The rover drilled the Cumberland sample from an area within a crater called Yellowknife Bay, which resembled an ancient lake bed. The rocks from Yellowknife Bay so intrigued Curiosity's science team that it had the rover drive in the opposite direction to collect samples from the area before heading to Mount Sharp. Since collecting the Cumberland sample, Curiosity has used SAM to study it in a variety of ways, revealing that Yellowknife Bay was once the site of an ancient lake where clay minerals formed in water. The mudstone created an environment that could concentrate and preserve organic molecules and trapped them inside the fine grains of the sedimentary rock. Freissinet helped lead a research team in 2015 that was able to identify organic molecules within the Cumberland sample. The instrument detected an abundance of sulfur, which can be used to preserve organic molecules; nitrates, which are essential for plant and animal health on Earth; and methane composed of a type of carbon associated with biological processes on Earth. 'There is evidence that liquid water existed in Gale Crater for millions of years and probably much longer, which means there was enough time for life-forming chemistry to happen in these crater-lake environments on Mars,' said study coauthor Daniel Glavin, senior scientist for sample return at NASA's Goddard Space Flight Center in Greenbelt, Maryland, in a statement. Curiosity has maintained pristine pieces of the Cumberland sample in a 'doggy bag' so that the team could have the rover revisit it later, even miles away from the site where it was collected. The team developed and tested innovative methods in its lab on Earth before sending messages to the rover to try experiments on the sample. In a quest to see whether amino acids, the building blocks of proteins, existed in the sample, the team instructed the rover to heat up the sample twice within SAM's oven. When it measured the mass of the molecules released during heating, there weren't any amino acids, but they found something entirely unexpected. The team was surprised to detect small amounts of decane, undecane and dodecane, so it had to conduct a reverse experiment on Earth to determine whether these organic compounds were the remnants of the fatty acids undecanoic acid, dodecanoic acid and tridecanoic acid, respectively. The scientists mixed undecanoic acid into a clay similar to what exists on Mars and heated it up in a way that mimicked conditions within SAM's oven. The undecanoic acid released decane, just like what Curiosity detected. Each fatty acid remnant detected by Curiosity was made with a long chain of 11 to 13 carbon atoms. Previous molecules detected on Mars were smaller, meaning their atomic weight was less than the molecules found in the new study, and simpler. 'It's notable that non-biological processes typically make shorter fatty acids, with less than 12 carbons,' said study coauthor Dr. Amy Williams, associate professor of geology at the University of Florida and assistant director of the Astraeus Space Institute, in an email. 'Larger and more complex molecules are likely what are required for an origin of life, if it ever occurred on Mars.' While the Cumberland sample may contain longer chains of fatty acids, SAM is not designed to detect them. But SAM's ability to spot these larger molecules suggests it could detect similar chemical signatures of past life on Mars if they're present, Williams said. 'Curiosity is not a life detection mission,' Freissinet said. 'Curiosity is a habitability detection mission to know if all the conditions were right … for life to evolve. Having these results, it's really at the edge of the capabilities of Curiosity, and it's even maybe better than what we had expected from this mission.' Before sending missions to Mars, scientists didn't think organic molecules would be found on the red planet because of the intensity of radiation Mars has long endured, Glavin said. Curiosity won't return to Yellowknife Bay during its mission, but there are still pristine pieces of the Cumberland sample aboard. Next, the team wants to design a new experiment to see what it can detect. If the team can identify similar long-chain molecules, it would mark another step forward that might help researchers determine their origins, Freissinet said. 'That's the most precious sample we have on board … waiting for us to run the perfect experiment on it,' she said. 'It holds secrets, and we need to decipher the secrets.' Briony Horgan, coinvestigator on the Perseverance rover mission and professor of planetary science at Purdue University in West Lafayette, Indiana, called the detection 'a big win for the whole team.' Horgan was not involved the study. 'This detection really confirms our hopes that sediments laid down in ancient watery environments on Mars could preserve a treasure trove of organic molecules that can tell us about everything from prebiotic processes and pathways for the origin of life, to potential biosignatures from ancient organisms,' Horgan said. Dr. Ben K.D. Pearce, assistant professor in Purdue's department of Earth, atmospheric, and planetary sciences and leader of the Laboratory for Origins and Astrobiology Research, called the findings 'arguably the most exciting organic detection to date on Mars.' Pearce did not participate in the research. Some scientists believe that fatty acids such as decanoic acid and dodecanoic acid formed the membranes of the first simple cell-like structures on Earth, Pearce said. '(This is) the closest we've come to detecting a major biomolecule-related signal — something potentially tied to membrane structure, which is a key feature of life,' Pearce said via email. 'Organics on their own are intriguing, but not evidence of life. In contrast, biomolecules like membranes, amino acids, nucleotides, and sugars are central components of biology as we know it, and finding any of them would be groundbreaking (we haven't yet).' The European Space Agency plans to launch its ExoMars Rosalind Franklin rover to the red planet in 2028, and the robotic explorer will carry a complementary instrument to SAM. The rover LS6 will have the capability to drill up to 6.5 feet (2 meters) beneath the Martian surface — and perhaps find larger and better-preserved organic molecules. While Curiosity's samples can't be studied on Earth, the Perseverance rover has actively been collecting samples from Jezero Crater, the site of an ancient lake and river delta, all with the intention of returning them to Earth in the 2030s via a complicated symphony of missions called Mars Sample Return. Both rovers have detected a variety of organic carbon molecules in different regions on Mars, suggesting that organic carbon is common on the red planet, Williams said. While Curiosity and Perseverance have proven they can detect organic matter, their instruments can't definitively determine all the answers about their origins, said Dr. Ashley Murphy, postdoctoral research scientist at the Planetary Science Institute. Murphy, who along with Williams previously studied organics identified by Perseverance, was not involved in the new research. 'To appropriately probe the biosignature question, these samples require high-resolution and high-sensitivity analyses in terrestrial labs, which can be facilitated by the return of these samples to Earth,' Murphy said. If the molecules within the Cumberland sample are the byproduct of microbial life that existed 3.7 billion years ago, such a finding would align with the same time frame as when scientists think life was starting on Earth, Glavin said. Curiosity's finding feels 'so close' to helping make that determination, but the answers are more likely to come from studying samples on Earth, he said. 'I'm more optimistic that we're going to finally be able to settle this life on Mars debate, which feels like it's been going on forever,' Glavin said.
CNN
29-03-2025
- Science
- CNN
Curiosity rover makes ‘arguably the most exciting organic detection to date on Mars'
The NASA Curiosity rover has detected the largest organic molecules found to date on Mars, opening a window into the red planet's past. The newly detected compounds suggest complex organic chemistry may have occurred in the planet's past — the kind necessary for the origin of life, according to new research. The organic compounds, which include decane, undecane and dodecane, came to light after the rover analyzed a pulverized 3.7 billion-year-old rock sample using its onboard mini lab called SAM, short for Sample Analysis at Mars. Scientists believe the long chains of molecules could be fragments of fatty acids, which are organic molecules that are chemical building blocks of life on Earth and help form cell membranes. But such compounds can also be formed without the presence of life, created when water interacts with minerals in hydrothermal vents. The molecules cannot currently be confirmed as evidence of past life on the red planet, but they add to the growing list of compounds that robotic explorers have discovered on Mars in recent years. A study detailing the findings was published Monday in the journal Proceedings of the National Academy of Sciences. The detection of the fragile molecules also encourages astrobiologists that if any biosignatures, or past signs of life, ever existed on Mars, they are likely still detectable despite the harsh solar radiation that has bombarded the planet for tens of millions of years. 'Ancient life, if it happened on Mars, it would have released some complex and fragile molecules,' said lead study author Dr. Caroline Freissinet, research scientist at the French National Centre for Scientific Research in the Laboratory for Atmospheres, Observations, and Space in Guyancourt, France. 'And because now we know that Mars can preserve these complex and fragile molecules, it means that we could detect ancient life on Mars.' The finding also adds fuel to the fire to return samples from Mars so scientists can study them on Earth with more sophisticated tools, and perhaps, once and for all, determine whether life ever existed anywhere beyond our planet. Curiosity landed in Gale Crater on August 6, 2012. More than 12 years later, the rover has driven over 21 miles (34 kilometers) to ascend Mount Sharp, which is within the crater. The feature's many layers preserve millions of years of geological history on Mars, showing how it shifted from a wet to a dry environment. Perhaps one of the most valuable samples Curiosity has gathered on its mission to understand whether Mars was ever habitable was collected in May 2013. The rover drilled the Cumberland sample from an area within a crater called Yellowknife Bay, which resembled an ancient lake bed. The rocks from Yellowknife Bay so intrigued Curiosity's science team that it had the rover drive in the opposite direction to collect samples from the area before heading to Mount Sharp. Since collecting the Cumberland sample, Curiosity has used SAM to study it in a variety of ways, revealing that Yellowknife Bay was once the site of an ancient lake where clay minerals formed in water. The mudstone created an environment that could concentrate and preserve organic molecules and trapped them inside the fine grains of the sedimentary rock. Freissinet helped lead a research team in 2015 that was able to identify organic molecules within the Cumberland sample. The instrument detected an abundance of sulfur, which can be used to preserve organic molecules; nitrates, which are essential for plant and animal health on Earth; and methane composed of a type of carbon associated with biological processes on Earth. 'There is evidence that liquid water existed in Gale Crater for millions of years and probably much longer, which means there was enough time for life-forming chemistry to happen in these crater-lake environments on Mars,' said study coauthor Daniel Glavin, senior scientist for sample return at NASA's Goddard Space Flight Center in Greenbelt, Maryland, in a statement. Curiosity has maintained pristine pieces of the Cumberland sample in a 'doggy bag' so that the team could have the rover revisit it later, even miles away from the site where it was collected. The team developed and tested innovative methods in its lab on Earth before sending messages to the rover to try experiments on the sample. In a quest to see whether amino acids, the building blocks of proteins, existed in the sample, the team instructed the rover to heat up the sample twice within SAM's oven. When it measured the mass of the molecules released during heating, there weren't any amino acids, but they found something entirely unexpected. The team was surprised to detect small amounts of decane, undecane and dodecane, so it had to conduct a reverse experiment on Earth to determine whether these organic compounds were the remnants of the fatty acids undecanoic acid, dodecanoic acid and tridecanoic acid, respectively. The scientists mixed undecanoic acid into a clay similar to what exists on Mars and heated it up in a way that mimicked conditions within SAM's oven. The undecanoic acid released decane, just like what Curiosity detected. Each fatty acid remnant detected by Curiosity was made with a long chain of 11 to 13 carbon atoms. Previous molecules detected on Mars were smaller, meaning their atomic weight was less than the molecules found in the new study, and simpler. 'It's notable that non-biological processes typically make shorter fatty acids, with less than 12 carbons,' said study coauthor Dr. Amy Williams, associate professor of geology at the University of Florida and assistant director of the Astraeus Space Institute, in an email. 'Larger and more complex molecules are likely what are required for an origin of life, if it ever occurred on Mars.' While the Cumberland sample may contain longer chains of fatty acids, SAM is not designed to detect them. But SAM's ability to spot these larger molecules suggests it could detect similar chemical signatures of past life on Mars if they're present, Williams said. 'Curiosity is not a life detection mission,' Freissinet said. 'Curiosity is a habitability detection mission to know if all the conditions were right … for life to evolve. Having these results, it's really at the edge of the capabilities of Curiosity, and it's even maybe better than what we had expected from this mission.' Before sending missions to Mars, scientists didn't think organic molecules would be found on the red planet because of the intensity of radiation Mars has long endured, Glavin said. Curiosity won't return to Yellowknife Bay during its mission, but there are still pristine pieces of the Cumberland sample aboard. Next, the team wants to design a new experiment to see what it can detect. If the team can identify similar long-chain molecules, it would mark another step forward that might help researchers determine their origins, Freissinet said. 'That's the most precious sample we have on board … waiting for us to run the perfect experiment on it,' she said. 'It holds secrets, and we need to decipher the secrets.' Briony Horgan, coinvestigator on the Perseverance rover mission and professor of planetary science at Purdue University in West Lafayette, Indiana, called the detection 'a big win for the whole team.' Horgan was not involved the study. 'This detection really confirms our hopes that sediments laid down in ancient watery environments on Mars could preserve a treasure trove of organic molecules that can tell us about everything from prebiotic processes and pathways for the origin of life, to potential biosignatures from ancient organisms,' Horgan said. Dr. Ben K.D. Pearce, assistant professor in Purdue's department of Earth, atmospheric, and planetary sciences and leader of the Laboratory for Origins and Astrobiology Research, called the findings 'arguably the most exciting organic detection to date on Mars.' Pearce did not participate in the research. Some scientists believe that fatty acids such as decanoic acid and dodecanoic acid formed the membranes of the first simple cell-like structures on Earth, Pearce said. '(This is) the closest we've come to detecting a major biomolecule-related signal — something potentially tied to membrane structure, which is a key feature of life,' Pearce said via email. 'Organics on their own are intriguing, but not evidence of life. In contrast, biomolecules like membranes, amino acids, nucleotides, and sugars are central components of biology as we know it, and finding any of them would be groundbreaking (we haven't yet).' The European Space Agency plans to launch its ExoMars Rosalind Franklin rover to the red planet in 2028, and the robotic explorer will carry a complementary instrument to SAM. The rover LS6 will have the capability to drill up to 6.5 feet (2 meters) beneath the Martian surface — and perhaps find larger and better-preserved organic molecules. While Curiosity's samples can't be studied on Earth, the Perseverance rover has actively been collecting samples from Jezero Crater, the site of an ancient lake and river delta, all with the intention of returning them to Earth in the 2030s via a complicated symphony of missions called Mars Sample Return. Both rovers have detected a variety of organic carbon molecules in different regions on Mars, suggesting that organic carbon is common on the red planet, Williams said. While Curiosity and Perseverance have proven they can detect organic matter, their instruments can't definitively determine all the answers about their origins, said Dr. Ashley Murphy, postdoctoral research scientist at the Planetary Science Institute. Murphy, who along with Williams previously studied organics identified by Perseverance, was not involved in the new research. 'To appropriately probe the biosignature question, these samples require high-resolution and high-sensitivity analyses in terrestrial labs, which can be facilitated by the return of these samples to Earth,' Murphy said. If the molecules within the Cumberland sample are the byproduct of microbial life that existed 3.7 billion years ago, such a finding would align with the same time frame as when scientists think life was starting on Earth, Glavin said. Curiosity's finding feels 'so close' to helping make that determination, but the answers are more likely to come from studying samples on Earth, he said. 'I'm more optimistic that we're going to finally be able to settle this life on Mars debate, which feels like it's been going on forever,' Glavin said.
