Alien life: Illustration of huge metallic telescope observatory. The top dome is split open, revealing a complex lattice structure inside.
View larger. | Artist’s concept of the Extremely Large Telescope (ELT). Currently being constructed in Chile, it will see 1st light in 2028 and help search for signs of alien life on exoplanets. In fact, it will be able to do so faster than ever before. Image via Swinburne Astronomy Productions/ ESO/ Wikimedia Commons (CC BY 4.0).
Is there alien life somewhere in our galaxy? The search for possible signs of biological activity on distant exoplanets is difficult and time-consuming.
The new Extremely Large Telescope, currently being constructed in Chile, will help expand that search. And it will do it much faster than current searches.
The telescope will analyze the atmospheres of some of the closer potentially habitable worlds about the size of Earth-Neptune. It will be able to identify possible signatures of biology in only a matter of hours.
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Searching for alien life with the Extremely Large Telescope
Is there other life out in the universe? We still don’t know for sure, but we are getting ever closer to finding it, if it exists. The upcoming Extremely Large Telescope (ELT) in Chile will represent a big leap toward answering the age-old question of “Are we alone?” And it could do so a lot faster than previously possible, researchers at the University of Washington and NASA’s Goddard Space Flight Center said in a new preprint paper on March 11, 2025.
Brian Koberlein wrote about the exciting prospects in Live Science on March 24, 2025.
The paper stated:
The upcoming extremely large telescopes will provide the first opportunity to search for signs of habitability and life on non-transiting terrestrial exoplanets using high-contrast, high-resolution instrumentation. However, the suite of atmospheric gases in terrestrial exoplanet environments that are accessible to ground-based reflected light observations has not been thoroughly explored. In this work, we use an upgraded Extremely Large Telescope (ELT) detectability pipeline to simulate the detectability of gases that can serve as habitability markers, potential biosignatures and false positive discriminants in the atmospheres of Earth-sized and sub-Neptune planets.
4 Earth-like scenarios
The new study simulated results from the Extremely Large Telescope in four different scenarios. All four scenarios involved “Earth-like” planets. The first was a planet with just photosynthesizing plants on its surface. The second was a younger planet akin to early Archean Earth, where microscopic life is just starting to become widespread starting about 4.6 billion years ago. The third was a planet that used to have oceans, but now no longer does, perhaps like Mars or Venus. Finally, the fourth scenario was a planet like Earth, but before life ever started.
The study focused on planets orbiting relatively nearby red dwarf stars. Notably, red dwarfs are the most common type of star in our galaxy. And to be sure, astronomers have found many rocky planets orbiting them in recent years. And that number keeps growing. This includes the nearest star to us, Proxima Centauri, which has at least one exoplanet. It is only 4.3 light-years away from us. In addition, the TRAPPIST-1 system, with seven known planets about the size of Earth, is another prime example.
Rocky planet with some water on its surface and bright sun in background.
View larger. | Artist’s concept of Proxima Centauri b, a rocky Earth-sized exoplanet orbiting a red dwarf star. It and Proxima Centauri c are the closest known exoplanets to Earth at 4.3 light-years. Image via ESO/ M. Kornmesser/ Wikimedia Commons (CC BY 4.0).
Finding alien life quickly
So, would the Extremely Large Telescope be able to detect signs of life in the atmospheres of such planets? The researchers found that indeed, it could. And quickly. In fact, it could detect biosignatures – chemical or other traces of life – on planets orbiting Proxima Centauri after only 10 hours of observations. Possible biosignatures can include oxygen, carbon dioxide, methane and other trace gases such as dimethyl sulfide.
For larger planets, like the ones closer in size to Neptune, the Extremely Large Telescope could produce results even faster, in as little as an hour. That’s much quicker than astronomers can achieve right now. Currently, those kinds of observations usually require weeks, months or even years. The paper said:
For the most accessible nearby target, Proxima Centauri b, our results suggest that we may be able to rule out a sub-Neptune atmosphere in as little as a single hour of observing, and two biosignature disequilibrium pairs (O2/CH4 and CO2/CH4) may be accessible in about 10 hours for the most optimistic scenario.
The Extremely Large Telescope, currently under construction in northern Chile, will give us a better view of the Milky Way than any ground-based telescope before it.www.livescience.com/space/exopla…
— Live Science (@livescience.com) 2025-03-24T21:08:15.536Z
Transiting and non-transiting planets
Also, the telescope will be able to analyze the atmospheres of planets that transit their stars as well as ones that don’t. In a transit, the planet crosses in front of the star as seen from here on Earth. Astronomers can analyze the spectra of the light from the star as the light passes through the planet’s atmosphere. Conversely, for non-transiting planets, the telescope will study the reflected light of the planets from their stars. As the paper noted:
In this work, we upgraded the existing SPECTR ELT detectability pipeline to include functionality for high spectral resolution observations of terrestrial exoplanets in reflected light.
The paper concluded:
While terrestrial exoplanet characterization is inherently challenging, the ELT era will likely offer the first opportunities to study the atmospheres of non-transiting terrestrial exoplanet targets, and search for signs of habitability and life on our nearest exoplanetary neighbors.
We don’t know yet what the Extremely Large Telescope will find, but it will be exciting to find out. As Koberlein wrote in Live Science:
So it seems that if life exists in a nearby star system, the ELT should be able to detect it. The answer to perhaps the greatest question in human history could be found in just a few years.
Bottom line: The upcoming Extremely Large Telescope could revolutionize the search for alien life, analyzing the atmospheres of nearby “Earth-like” planets in only hours.
Source: There’s more to life in reflected light: Simulating the detectability of a range of molecules for high-contrast, high-resolution observations of non-transiting terrestrial exoplanets (preprint)
Via Live Science
Paul Scott Anderson
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About the Author:
Paul Scott Anderson has had a passion for space exploration that began when he was a child when he watched Carl Sagan’s Cosmos. He studied English, writing, art and computer/publication design in high school and college. He later started his blog The Meridiani Journal in 2005, which was later renamed Planetaria. He also later started the blog Fermi Paradoxica, about the search for life elsewhere in the universe. While interested in all aspects of space exploration, his primary passion is planetary science and SETI. In 2011, he started writing about space on a freelance basis with Universe Today. He has also written for SpaceFlight Insider and AmericaSpace and has also been published in The Mars Quarterly. He also did some supplementary writing for the iOS app Exoplanet. He has been writing for EarthSky since 2018, and also assists with proofing and social media.