Latest news with #K2-18
New Indian Express
03-05-2025
- Science
- New Indian Express
Face earth's challenges while searching extra-terrestrial life
K2-18b revolves around a cool dwarf star called K2-18 in the constellation Leo. Although it is about 8.6 times the mass of Earth, its orbit around its dim parent star is much closer, qualifying it to be in a habitable zone with the possibility of liquid water on or under its surface. The detection of bio-signatures has led to speculation that at least microbial life could exist on K2-18b, much like on Earth billions of years ago. A hint of extra-terrestrial (ET) life detected from observations by the James Webb Space Telescope has got the world bubbling with excitement. A study of exoplanet K2-18b has indicated bio-signatures or chemical fingerprints of biological activity, particularly the presence of methane, carbon dioxide and dimethyl sulphide and/or dimethyl disulphide in its atmosphere. The excitement is justified. Finding bio-signatures on an exoplanet is a first. However, what the scientists, led by those from the University of Cambridge, have detected only indicates the possibility of life. But in what form it exists, if at all, is not known. For that, significantly more advanced technologies are needed, as the study of bio-signatures is still in its infancy. Detection of just the chemical fingerprints, although an important beginning, cannot qualify as a 'scientific discovery'. Despite that, hopes to find ET life should not be lost. The probability of it existing on millions—or even billions—of exoplanets across the universe is considered much higher now than ever before. But as we go looking for signs of life light-years away, let us not forget that we have not yet explored more than a tenth of our own terrestrial oceans, from the depths of which life is understood to have begun 3.5 billion years ago on this 4.54 billion-year-old Earth. Nor has the human species been able to protect itself from itself, let alone the 90 percent of species that went extinct due to anthropogenic factors since humans took the first steps just 3,00,000 years ago. We remain challenged, not just technologically, but also in our capabilities to sustain ourselves, our ecology and our environment. That is a challenge worth overcoming.
CBC
29-04-2025
- Science
- CBC
Scientists skeptical about recent claims that signs of life were possibly detected on exoplanet
The search for life beyond our own planet is something that astronomers have been doing for decades now, with no results. But on April 17, a study was published revealing that a team of astronomers using the James Webb Space Telescope (JWST), led by Nikku Madhusudhan, had discovered gases on an exoplanet called K2-18b that could only be produced by life. Right off the bat, many astronomers were a little skeptical about the claim, saying there wasn't robust evidence to support the findings. "Discoveries like this ... usually takes a long time to confirm, and many times it turned out not true," Yanqin Wu told CBC News on the day it was announced. "That's just the disappointment in real scientific endeavour. Extraordinary claims usually takes a lot of proof and usually are wrong." Now, a new independent analysis of the JWST data has found no evidence of biosignatures, signs that the planet's gases may have a biological origin. Madhusudhan and his colleagues used data collected from JWST of the planet passing in front of its host star, K2-18, and the different molecules that were observed in the spectra. This method is useful for determining which chemicals are in the air of a planet. The study found the presence of two gases — dimethyl sulfide, or DMS, and dimethyl disulfide, or DMDS — which are typically produced on Earth by algae. But Jake Taylor, a planetary scientist who also studies exoplanets using JWST data, used that data and examined it using a different method than the Madhusudhan-led study and was unable to replicate the findings. He published his results on the pre-print site ArXiv. WATCH | Scientists make 'major breakthrough' in search for life outside solar system: Scientists make 'major breakthrough' in search for life outside solar system 12 days ago Duration 1:43 Prof. Nikku Madhusudhan, a Cambridge University astrophysicist, says the discovery of two gases — dimethyl sulfide, or DMS, and dimethyl disulfide, or DMDS — in the atmosphere of a planet will be seen as a 'paradigm shift in our search for life.' Scientists used NASA's James Webb Space Telescope to make the discovery about K2-18 b, a planet found about 124 light-years from Earth. In his method, he used an "agnostic" approach, meaning he didn't look for any sulfur gases that could be signs of life like there are here on Earth. The result was a "flat line" rather than any wiggles in the data, meaning that the dips found in the initial study were statistical noise — random information that can effect study results. Taylor said he was excited about the study and thought it was good in some ways, but "when it came to the atmospheric physics side, I noticed that they didn't give too much detail about their flat-line rejection tests." He explained these tests are "kind of a standard within the field" to do first in order to ensure there isn't noise in the data. He said he did speak with Madhusudhan personally about this last week, who reassured him that the rejection tests had been conducted, though they weren't contained in the study itself. Though he said the current data from JWST didn't provide enough confidence in a biosignature detection, it doesn't mean it couldn't happen with additional data. "It's a good first step in in this sort of endeavour, because this is a spectral range we've never seen before. So just that in itself is pretty cool," Taylor said. "We definitely would need more observations to get a better signal. And who knows, it might pop out, it might be there. It's just right now, the signal-to-noise ratio is not definitive." Asked if there needs to be more rigorous examinations of such claims, Taylor said, "I think there needs to be more discussions about this. I do personally think that there needs to be multiple lines of evidence, and also there needs to be like a model independent confirmation that we see something." Taylor admitted he was a big fan of The X-Files, a sci-fi show that largely focused on finding proof of alien life on Earth. Its most touted catchphrase was "I want to believe." He also noted that planetary scientists looking for signs of life on exoplanets do really want to one day find that robust sign of life, though it's not like we could ever visit the exoplanet to confirm with certainty. "We want to believe," he said. "But we want to do it correctly."
Forbes
26-04-2025
- Science
- Forbes
Why We Should Be Wary Of The Putative K2-18b Extrasolar Biosignature
This illustration shows what exoplanet K2-18 b could look like based on science data. K2-18 b, an ... More exoplanet 8.6 times as massive as Earth, orbits the cool dwarf star K2-18 in the habitable zone and lies 120 light years from Earth. In the high stakes science of looking for signatures of life on a planet circling another sunlike star, understandably, there's pressure to produce results. Thus, news that a University of Cambridge-led team in the U.K. had detected dimethyl sulfide (DMS), a sulfur-rich potential biosignature on a hydrogen-rich ocean-world some 124 light years away, was music to many astrobiologists' ears. With fresh data from NASA's James Webb Space Telescope, the team reported the detection of the spectroscopic chemical fingerprints of dimethyl sulfide (DMS) and/or its cousin, dimethyl disulfide (DMDS), in the atmosphere of the exoplanet K2-18b. The planet, which is some 2.6 times as large as Earth, orbits its star in the habitable zone, which as noted in a paper appearing in The Astrophysical Journal Letters is crucial to the argument that the planet might harbor some crude form of life. But within 72 hours of this news, there was an online outcry among several cosmochemists who cast aspersions on the idea. The bio-signature is dimethyl sulfide, a molecule known to be present in interstellar clouds and a comet, Sun Kwok, a former president of the International Astronomical Union's Commission on Astrobiology and an astronomer at the University of British Columbia in Vancouver, tells me via email. The reported detection of this molecule in a planet, if real, is most likely the result of abiotic processes and has nothing to do with life, he says. On Earth, as the University of Cambridge notes, dimethyl sulfide is only produced by microbial life, such as marine phytoplankton. Just because a volatile molecule is in a comet or the interstellar medium doesn't mean much for a planetary atmosphere, Nikku Madhusudhan, the paper's lead author and an astrophysicist at the university of Cambridge in the U.K., tells me via email. Several biomarkers including methane and molecular oxygen are also present in those environments but have very little implication for planetary atmospheres, he says. The key point is that dimethyl sulfide can be produced in such environments in very small quantities, but much less than what is required to explain our observations, says Madhusudhan. Yet Kwok sticks by his assertion that abiotic process that can produce dimethyl sulfide are common and effective. So, one cannot conclude that its detection is biological in origin, when other explanations are possible, he says. One can only make such an extraordinary claim when other possibilities are eliminated, says Kwok. But Madhusudhan disagrees. Dimethyl sulfide is much more unstable in a planetary atmosphere than in a comet and hence has very short lifetimes unless replenished continuously, says Madhusudhan. To date, it has not been shown that this can be a viable mechanism to explain DMS on habitable planets, he says. As for these hydrogen-rich ocean worlds potentially harboring microbial life? There are many biochemical pathways to life, and we should not push Earth analogs too far, says Kwok. I am pessimistic about detecting life as we know it but optimistic about the wide presence of extraterrestrial life in other forms, he says. What should we be doing that we aren't? Before we seek biosignatures, I would like to see a satellite-based infrared spectrometer with high spectral resolution, says Kwok. This would enable us to identify the structures of complex organic compounds in space to gain a better understanding of the abiotic synthesis of organics, he says. Is finding extrasolar biosignatures an impossible task? Planetary scientists have found a large variety of organic compounds (including nearly 100 amino acids in meteorites, all formed abiotically, says Kwok. So, it is very difficult to find a biosignature in exoplanets that can be conclusively identified as biological in origin, he says. The best chance to find life beyond the Earth is through planetary exploration using in situ observations or sample return, says Kwok. Yet even if this turns out to be a spurious detection, it's heartening to know that we now can potentially find complex molecules on worlds totally unlike our own, many light years away.
Yomiuri Shimbun
25-04-2025
- Science
- Yomiuri Shimbun
Scientists Discover Strongest Evidence Yet of Life on Exoplanet
A. Smith, N. Madhusudhan / University of Cambridge / Handout via Reuters A graph shows the observed transmission spectrum of the habitable zone exoplanet K2-18 b using the James Webb Space Telescope MIRI spectrograph instrument. The vertical shows the fraction of star light absorbed in the planet's atmosphere due to molecules in its atmosphere. The data are shown in the yellow circles with the 1-sigma uncertainties. The curves show the model fits to the data, with the black curve showing the median fit and the cyan curves outlining the 1-sigma intervals of the model fits. The absorption features attributed to dimethyl sulphide and dimethyl disulphide are indicated by the horizontal lines and text. Theses images were obtained on April 16. WASHINGTON (Reuters) — In a potential landmark discovery, scientists using the James Webb Space Telescope have obtained what they call the strongest signs yet of possible life beyond our solar system, detecting in an alien planet's atmosphere the chemical fingerprints of gases that on Earth are produced only by biological processes. The two gases — dimethyl sulfide, or DMS, and dimethyl disulfide, or DMDS — involved in Webb's observations of the planet named K2-18 b are generated on Earth by living organisms, primarily microbial life such as marine phytoplankton — algae. This suggests the planet may be teeming with microbial life, the researchers said. They stressed, however, that they are not announcing the discovery of actual living organisms but rather a possible biosignature — an indicator of a biological process — and that the findings should be viewed cautiously, with more observations needed. Nonetheless, they voiced excitement. These are the first hints of an alien world that is possibly inhabited, said astrophysicist Nikku Madhusudhan of the University of Cambridge's Institute of Astronomy, lead author of the study published in the Astrophysical Journal Letters. 'This is a transformational moment in the search for life beyond the solar system, where we have demonstrated that it is possible to detect biosignatures in potentially habitable planets with current facilities. We have entered the era of observational astrobiology,' Madhusudhan said. Madhusudhan noted that there are various efforts underway searching for signs of life in our solar system, including various claims of environments that might be conducive to life in places like Mars, Venus and various icy moons. K2-18 b is 8.6 times as massive as Earth and has a diameter about 2.6 times as large as our planet. It orbits in the 'habitable zone' — a distance where liquid water, a key ingredient for life, can exist on a planetary surface — around a red dwarf star smaller and less luminous than our sun, located about 124 light-years from Earth in the constellation Leo. 'Hycean world' About 5,800 planets beyond our solar system, called exoplanets, have been discovered since the 1990s. Scientists have hypothesized the existence of exoplanets called hycean worlds — covered by a liquid water ocean habitable by microorganisms and with a hydrogen-rich atmosphere. Earlier observations by Webb, which was launched in 2021 and became operational in 2022, had identified methane and carbon dioxide in K2-18 b's atmosphere, the first time that carbon-based molecules were discovered in the atmosphere of an exoplanet in a star's habitable zone. 'The only scenario that currently explains all the data obtained so far from JWST (James Webb Space Telescope), including the past and present observations, is one where K2-18 b is a hycean world teeming with life,' Madhusudhan said. 'However, we need to be open and continue exploring other scenarios.' Madhusudhan said that with hycean worlds, if they exist, 'we are talking about microbial life, possibly like what we see in the Earth's oceans.' Their oceans are hypothesized to be warmer than Earth's. Asked about possible multicellular organisms or even intelligent life, Madhusudhan said, 'We won't be able to answer this question at this stage. The baseline assumption is of simple microbial life.' DMS and DMDS, both from the same chemical family, have been predicted as important exoplanet biosignatures. Webb found that one or the other, or possibly both, were present in the planet's atmosphere at a 99.7% confidence level, meaning there is still a 0.3% chance of the observation being a statistical fluke. A. Smith, N. Madhusudhan / University of Cambridge / Handout via Reuters An illustration shows a hycean world — an exoplanet with a liquid water ocean beneath a hydrogen-rich atmosphere — orbiting a red dwarf star. Based on observations by the James Webb Space Telescope, the exoplanet K2-18 b might fit in this category. The gases were detected at atmospheric concentrations of more than 10 parts per million by volume. 'For reference, this is thousands of times higher than their concentrations in the Earth's atmosphere, and cannot be explained without biological activity based on existing knowledge,' Madhusudhan said. Scientists not involved in the study counseled circumspection. 'The rich data from K2-18 b make it a tantalizing world,' said Christopher Glein, principal scientist at the Space Science Division of the Southwest Research Institute in Texas. 'These latest data are a valuable contribution to our understanding. Yet, we must be very careful to test the data as thoroughly as possible.' Transit method K2-18 b is part of the 'sub-Neptune' class of planets, with a diameter greater than Earth's but less than that of Neptune, our solar system's smallest gas planet. To ascertain the chemical composition of an exoplanet's atmosphere, astronomers analyze the light from its host star as the planet passes in front of it from the perspective of Earth, called the transit method. As the planet transits, Webb can detect a decrease in stellar brightness, and a small fraction of starlight passes through the planetary atmosphere before being detected by the telescope. This lets scientists determine the constituent gases of the planet's atmosphere. Webb's previous observations of this planet provided a tentative hint of DMS. Its new observations used a different instrument and a different wavelength range of light. The 'Holy Grail' of exoplanet science, Madhusudhan said, is to find evidence of life on an Earth-like planet beyond our solar system. Madhusudhan said that our species for thousands of years has wondered 'are we alone' in the universe, and now might be within just a few years of detecting possible alien life on a hycean world. But Madhusudhan still urged caution. 'First we need to repeat the observations two to three times to make sure the signal we are seeing is robust and to increase the detection significance' to the level at which the odds of a statistical fluke are below roughly one in a million, Madhusudhan said. 'Second, we need more theoretical and experimental studies to make sure whether or not there is another abiotic mechanism [one not involving biological processes] to make DMS or DMDS in a planetary atmosphere like that of K2-18 b. Even though previous studies have suggested them [as] robust biosignatures even for K2-18 b, we need to remain open and pursue other possibilities,' Madhusudhan said. So the findings represent 'a big if' on whether the observations are due to life, and it is in 'no one's interest to claim prematurely that we have detected life,' Madhusudhan said.
Gulf News
19-04-2025
- Science
- Gulf News
Who is Nikku Madhusudhan, the Indian-origin scientist behind breakthrough in search for life outside the Earth
The name of Dr Nikku Madhusudhan exploded in the public domain with his breakthrough research on a planet named K2-18b. What made the announcement significant was his assertion that his team has found the most promising sign yet of a possible biosignature outside the solar system. 'This is the strongest evidence yet there is possibly life out there. I can realistically say that we can confirm this signal within one to two years,' said Dr Madhusudhan. This could be one of the most significant discoveries in the history of science and humankind – if proved true. And he is positive about it. What did his team find? Dr Madhusudhan and his team found chemical fingerprints of dimethyl sulfide (DMS), in the atmosphere of the exoplanet K2-18b. It is a molecule linked to life on Earth. They have used data from the James Webb Space Telescope (JWST) to arrive at this conclusion. K2-18b is an exoplanet 124 light years away from Earth. Exoplanet simply means it is a planet outside of our Solar System. It orbits the red dwarf star K2-18 and is located in the Leo constellation. Who is Nikku Madhusudhan? Dr Nikku Madhusudhan is an Associate Professor in Astrophysics, at the Institute of Astronomy at the University of Cambridge. Born in India, Dr Madhusudhan is educated in India and abroad. He obtained a from the Indian Institute of Technology (BHU) Varanasi and later earned an M.S. and Ph.D. in planetary science from the Massachusetts Institute of Technology (MIT). According to his Cambridge University profile, he is widely known for pioneering the inverse techniques to measure atmospheric properties of exoplanets based on their atmospheric spectra observed using a wide array of observational facilities in space and from the ground. His other notable studies include estimations of chemical compositions of exoplanetary atmospheres and interiors, and using them to investigate the formation mechanisms of exoplanets. Before joining Cambridge, Dr Madhusudhan held postdoctoral positions at MIT, Princeton, and Yale (where he was the YCAA Prize Postdoctoral Fellow). Dr Madhusudhan has received several awards, including the EAS MERAC Prize in Theoretical Astrophysics (2019), the IUPAP Young Scientist Medal in Astrophysics (2016), and the ASI Vainu Bappu Gold Medal (2014) How far is 124 light years? How far away is this exoplanet? A light-year is the distance that light travels in one Earth year. In one second, light travels 299,792,458 meters. So one light year would be approximately 9.461x 10 12 kilometres. Most of us would have already lost the sense of distance with this number. And 124 light-years would be 124 times this figure, which turns out to be 1.17x10 15 km.
