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By NASA
4 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
What Would It Take to Say We Found Life?
We call this the podium test. What would it take for you personally to confidently stand up in front of an international audience and make that claim? When you put it in that way, I think for a lot of scientists, the bar is really high.
So of course, there would be obvious things, you know, a very clear signature of technology or a skeleton or something like that. But we think that a lot of the evidence that we might encounter first will be much more subtle. For example, chemical signs of life that have to be detected above a background of abiotic chemistry. And really, what we see might depend a lot on where we look.
On Mars, for example, the long history of exploration there gives us a lot of context for what we might find. But we’re potentially talking about samples that are billions of years old in those cases, and on Earth, those kinds of samples, the evidence of life is often degraded and difficult to detect.
On the ocean worlds of our outer solar system, so places like Jupiter’s moon Europa and Saturn’s moon Enceladus, there’s the tantalizing possibility of extant life, meaning life that’s still alive. But potentially we’re talking about exceedingly small amounts of samples that would have to be analyzed with a relatively limited amount of instrumentation that can be carried from Earth billions of miles away.
And then for exoplanets, these are planets beyond our own solar system. Really, what we’re looking for there are very large magnitude signs of life that can be detectable through a telescope from many light-years away. So changes like the oxygenation of Earth’s atmosphere or changes in surface color.
So any one of those things, if they rose to the suspicion of being evidence of life, would be really heavily scrutinized in a very sort of specific and custom way to that particular observation. But I think there are also some general principles that we can follow. And the first is just: Are we sure we’re seeing what we think we’re seeing? Many of these environments are not very well known to us, and so we need to convince ourselves that we’re actually seeing a clear signal that represents what we think it represents.
Carl Sagan once said, “Life is the hypothesis of last resort,” meaning that we ought to work hard for such a claim to rule out alternative possibilities. So what are those possibilities? One is contamination. The spacecraft and the instruments that we use to look for evidence of life are built in an environment, Earth, that is full of life. And so we need to convince ourselves that what we’re seeing is not evidence of our own life, but evidence of indigenous life.
If that’s the case, we should ask, should life of the type we’re seeing live there? And finally, we need to ask, is there any other way than life to make that thing, any of the possible abiotic processes that we know and even the ones that we don’t know? And as you can imagine, that will be quite a challenge.
Once we have a piece of evidence in hand that we really do think represents evidence of life, now we can begin to develop hypotheses. For example, do we have separate independent lines of evidence that corroborate what we’ve seen and increase our confidence of life?
Ultimately, all of this has to be looked at hard by the entire scientific community, and in that sense, I think the really operative word in our question is we. What does it take to say we found evidence of life? Because really, the answer, I think, depends on the full scientific community scrutinizing and skepticizing this observation to finally say that we scientists, we as a community and we as humanity found life.
[END VIDEO TRANSCRIPT]
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By Space Force
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By NASA
Researchers analyzing pulverized rock onboard NASA’s Curiosity rover have found the largest organic compounds on the Red Planet to date. The finding, published Monday in the Proceedings of the National Academy of Sciences, suggests prebiotic chemistry may have advanced further on Mars than previously observed.
Scientists probed an existing rock sample inside Curiosity’s Sample Analysis at Mars (SAM) mini-lab and found the molecules decane, undecane, and dodecane. These compounds, which are made up of 10, 11, and 12 carbons, respectively, are thought to be the fragments of fatty acids that were preserved in the sample. Fatty acids are among the organic molecules that on Earth are chemical building blocks of life.
Living things produce fatty acids to help form cell membranes and perform various other functions. But fatty acids also can be made without life, through chemical reactions triggered by various geological processes, including the interaction of water with minerals in hydrothermal vents.
While there’s no way to confirm the source of the molecules identified, finding them at all is exciting for Curiosity’s science team for a couple of reasons.
Curiosity scientists had previously discovered small, simple organic molecules on Mars, but finding these larger compounds provides the first evidence that organic chemistry advanced toward the kind of complexity required for an origin of life on Mars.
This graphic shows the long-chain organic molecules decane, undecane, and dodecane. These are the largest organic molecules discovered on Mars to date. They were detected in a drilled rock sample called “Cumberland” that was analyzed by the Sample Analysis at Mars lab inside the belly of NASA’s Curiosity rover. The rover, whose selfie is on the right side of the image, has been exploring Gale Crater since 2012. An image of the Cumberland drill hole is faintly visible in the background of the molecule chains. NASA/Dan Gallagher The new study also increases the chances that large organic molecules that can be made only in the presence of life, known as “biosignatures,” could be preserved on Mars, allaying concerns that such compounds get destroyed after tens of millions of years of exposure to intense radiation and oxidation.
This finding bodes well for plans to bring samples from Mars to Earth to analyze them with the most sophisticated instruments available here, the scientists say.
“Our study proves that, even today, by analyzing Mars samples we could detect chemical signatures of past life, if it ever existed on Mars,” said Caroline Freissinet, the lead study author and research scientist at the French National Centre for Scientific Research in the Laboratory for Atmospheres and Space Observations in Guyancourt, France
In 2015, Freissinet co-led a team that, in a first, conclusively identified Martian organic molecules in the same sample that was used for the current study. Nicknamed “Cumberland,” the sample has been analyzed many times with SAM using different techniques.
NASA’s Curiosity rover drilled into this rock target, “Cumberland,” during the 279th Martian day, or sol, of the rover’s work on Mars (May 19, 2013) and collected a powdered sample of material from the rock’s interior. Curiosity used the Mars Hand Lens Imager camera on the rover’s arm to capture this view of the hole in Cumberland on the same sol as the hole was drilled. The diameter of the hole is about 0.6 inches. The depth of the hole is about 2.6 inches. NASA/JPL-Caltech/MSSS Curiosity drilled the Cumberland sample in May 2013 from an area in Mars’ Gale Crater called “Yellowknife Bay.” Scientists were so intrigued by Yellowknife Bay, which looked like an ancient lakebed, they sent the rover there before heading in the opposite direction to its primary destination of Mount Sharp, which rises from the floor of the crater.
The detour was worth it: Cumberland turns out to be jam-packed with tantalizing chemical clues to Gale Crater’s 3.7-billion-year past. Scientists have previously found the sample to be rich in clay minerals, which form in water. It has abundant sulfur, which can help preserve organic molecules. Cumberland also has lots of nitrates, which on Earth are essential to the health of plants and animals, and methane made with a type of carbon that on Earth is associated with biological processes.
Perhaps most important, scientists determined that Yellowknife Bay was indeed the site of an ancient lake, providing an environment that could concentrate organic molecules and preserve them in fine-grained sedimentary rock called mudstone.
“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 Daniel Glavin, senior scientist for sample return at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and a study co-author.
The recent organic compounds discovery was a side effect of an unrelated experiment to probe Cumberland for signs of amino acids, which are the building blocks of proteins. After heating the sample twice in SAM’s oven and then measuring the mass of the molecules released, the team saw no evidence of amino acids. But they noticed that the sample released small amounts of decane, undecane, and dodecane.
Because these compounds could have broken off from larger molecules during heating, scientists worked backward to figure out what structures they may have come from. They hypothesized these molecules were remnants of the fatty acids undecanoic acid, dodecanoic acid, and tridecanoic acid, respectively.
The scientists tested their prediction in the lab, mixing undecanoic acid into a Mars-like clay and conducting a SAM-like experiment. After being heated, the undecanoic acid released decane, as predicted. The researchers then referenced experiments already published by other scientists to show that the undecane could have broken off from dodecanoic acid and dodecane from tridecanoic acid.
The authors found an additional intriguing detail in their study related to the number of carbon atoms that make up the presumed fatty acids in the sample. The backbone of each fatty acid is a long, straight chain of 11 to 13 carbons, depending on the molecule. Notably, non-biological processes typically make shorter fatty acids, with less than 12 carbons.
It’s possible that the Cumberland sample has longer-chain fatty acids, the scientists say, but SAM is not optimized to detect longer chains.
Scientists say that, ultimately, there’s a limit to how much they can infer from molecule-hunting instruments that can be sent to Mars. “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 research was funded by NASA’s Mars Exploration Program. Curiosity’s Mars Science Laboratory mission is led by NASA’s Jet Propulsion Laboratory in Southern California; JPL is managed by Caltech for NASA. SAM (Sample Analysis at Mars) was built and tested at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. CNES (the French Space Agency) funded and provided the gas chromatograph subsystem on SAM. Charles Malespin is SAM’s principal investigator.
By Lonnie Shekhtman
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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By NASA
Lee esta historia en español aquí
When Rose Ferreira first saw an image of a field of galaxies and galaxy clusters from NASA’s James Webb Space Telescope in July, she “went into the restroom and broke down a little,” she said. This “Deep Field” image showed galaxies not only sharper, but deeper into the universe than a similar image she loved from the Hubble Space Telescope.
“Being able to contribute in any way to the efforts of the team within NASA that released this new Deep Field just felt like such a profound thing for me,” said Ferreira, a student at Arizona State University who interned with NASA this summer. “I was just a little bit in shock for, like, a week.”
Rose Ferreira estudia ciencias planetarias y astronomía en la Universidad Estatal de Arizona.Credits: James Mayer Webb, the largest space science telescope ever, which launched in December 2021, played a big role in Ferreira’s internship at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. She also supported a series of live news interviews for Webb’s first images and multimedia tasks for NASA’s Spanish-language communications program.
Growing up in the Dominican Republic, Ferreira said she didn’t have access to science education. She was taught skills like cooking and cleaning; she didn’t know NASA existed at that time.
But during the frequent blackouts in her village, when the Moon provided the only light, Rose Ferreira often wondered – what is the Moon all about? “The moonlight is a lot of what I used to see, and I was always so curious about that,” she said. “That obsession is what made me start asking questions.”
When she came to New York, she was placed in an underserved high school that sent her back multiple grades because they weren’t satisfied with her English language skills. She left and earned a GED diploma instead, hoping to go to college faster.
At age 18, Ferreira became homeless in New York and lived in train stations. By working as a home health aide, she was able to earn enough to rent an apartment in Queens and, eventually, get an associate degree.
Life threw other major challenges at her, including getting hit by a car and a cancer diagnosis.
Ferreira ultimately enrolled in a planetary science and astronomy degree program at Arizona State University. She received a “great birthday present” in the spring of 2022: her official acceptance to NASA’s internship program.
Among the highlights of her NASA experience was recording a voice-over in Spanish for a This Week at NASA video. She also served as a panelist at an event for the Minority University Research and Education Project, organized by NASA’s Office of STEM Engagement.
Ferreira dreams of becoming an astronaut and has a shorter-term goal of earning a doctorate. But the internship also fueled her passion for sharing space science with the public. Chatting with Goddard astrophysicist Dr. Michelle Thaller, host of the Webb broadcasts, was especially meaningful to her.
Rose Ferreira, foreground, in the broadcast control room at NASA’s Goddard Space Flight Center in July 2022.Credits: NASA She has this advice for young people who are also interested in pursuing space science: “Coming from a person who had it a bit harder to get there, I think: first, figure out if it is really what you love. And if it is really what you love, then literally find a way to do it no matter who says what.”
Besides Webb, Ferreira is excited about NASA’s Artemis program, which connects with her passion for the Moon. Through Artemis, NASA will send astronauts to establish a long-term presence on and around the Moon. She’s looking forward to what Artemis will uncover about the Moon’s geology and history while the agency uses the Moon to get ready for human exploration of Mars.
“Even when I was living on the streets, the Moon used to be the thing I looked at to calm myself. It’s my sense of comfort, even today when I’m overwhelmed by things,” she said. “It’s like a driving force.”
Written by Elizabeth Landau
NASA Headquarters
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By Space Force
Space Launch Delta 45 continued to “set the pace for space” as the world’s busiest spaceport in 2024. The SLD 45 team enabled 93 launches from the Eastern Range in 2024.
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