With the promise of revolutionizing our view of nearby star systems, the Extremely Large Telescope (ELT) is poised to do something no ground-based observatory has done before: detect potential signs of life on a planet orbiting the closest star to the Sun— Proxima Centauri —in under half a day. A new simulation study outlines how, thanks to its massive light-gathering power and unprecedented resolution, the ELT may be able to distinguish between living and lifeless planets based solely on the reflected light from their atmospheres.
This breakthrough possibility is detailed in a 2025 study by Miles H. Currie and Victoria S. Meadows , which models the telescope’s ability to extract molecular fingerprints from exoplanets that don’t even transit their host stars. Their preprint, available on arXiv , suggests the answer to one of astronomy’s most enduring questions— are we alone? —might be just a few years away.
The next leap in Earth-based astronomy
Set high in the Chilean Atacama Desert, the ELT is scheduled to begin operations in 2028. With a primary mirror spanning 39 meters, it will be the largest optical/infrared telescope ever built on Earth. Its enormous surface area will allow it to collect more light than any previous ground-based telescope—and produce images up to 16 times sharper than Hubble.
While other telescopes like JWST have made progress in analyzing exoplanet atmospheres during planetary transits, they face limitations. Most notably, many exoplanets—including some of the most promising Earth-like ones— do not transit from our line of sight. That’s where the ELT changes the game.
Instead of waiting for a planet to pass in front of its star, the ELT will be able to capture reflected starlight directly from exoplanetary atmospheres. Using advanced high-contrast imaging and spectroscopy , it can isolate molecular signatures such as oxygen , carbon dioxide , and water vapor —markers that could hint at biological activity.
Simulating the search for life
To evaluate the ELT’s potential, Currie and Meadows created detailed simulations of four Earth-like worlds orbiting nearby red dwarf stars :
・A lush, non-industrial Earth, rich in water and plant life
・An ancient Archean Earth, with primitive life and minimal oxygen
・A desiccated, oceanless world, more like Venus or Mars
・A barren, prebiotic Earth, with the chemistry for life but no organisms
The researchers also modeled Neptune-sized exoplanets for contrast, expecting their thick atmospheres to yield different spectral patterns.
Their goal: determine whether the ELT could reliably distinguish between living and lifeless planets, while avoiding false positives or false negatives. Could a planet without life appear to be thriving—or worse, could a truly habitable world be mistaken for a dead one?
Their conclusion was clear: with only ten hours of observation, the ELT could likely identify atmospheric biosignatures on an Earth-like planet around Proxima Centauri. For gas giants, meaningful spectra could be obtained in just an hour.
Proxima Centauri: the prime target
Orbiting just 4.24 light-years away, Proxima Centauri is home to at least two known exoplanets—Proxima b and Proxima d. While the exact habitability of Proxima b is still debated, its location within the star’s habitable zone and relative proximity to Earth make it a prime candidate for future observations.
If even a thin atmosphere exists around Proxima b, the ELT might be able to detect it. And if that atmosphere contains molecules associated with biology, the implications would be staggering.
With the telescope’s capabilities, astronomers won’t need to rely solely on rare planetary alignments or indirect detection. They’ll be able to observe exoplanets directly, opening the door to a more continuous and detailed survey of nearby planetary systems.
Beyond detection: preventing misinterpretation
Importantly, the study also highlights the risk of spectral ambiguity. Not every detection of oxygen or methane should be taken as a smoking gun for life. Natural, abiotic processes can mimic the chemical output of organisms.
That’s why the ELT’s resolution and sensitivity are so critical. By combining multiple spectral features and high-resolution data, researchers hope to develop stronger biosignature frameworks, reducing the likelihood of mistaken conclusions.
In this context, the ELT will not just search for life—it will help define what counts as evidence.
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