Which telescope will be 1st to find alien life? Scientists have some ideas

The future of exoplanet science looks particularly promising with the upcoming European Extremely Large Telescope (ELT), which is set to revolutionize our ability to detect signs of life on distant planets. According to a recent study, this telescope will be our best tool in the next two decades for identifying biosignatures—molecules that could indicate the presence of life—on rocky exoplanets orbiting nearby stars, like Proxima Centauri b.

Astronomers are especially excited about the ELT's potential to characterize exoplanetary atmospheres, a critical step in determining whether a planet might be habitable. Currently, the James Webb Space Telescope (JWST) is our leading instrument for studying exoplanet atmospheres using a technique called transit spectroscopy. This method involves observing the light of a star as a planet passes in front of it. The light filters through the planet's atmosphere, allowing scientists to detect the presence of specific molecules based on the light absorbed at certain wavelengths.

However, transit spectroscopy has its limitations. It only works for the small fraction of exoplanets that transit their stars from our viewpoint. For those that don’t transit—or those we can't observe transiting—direct imaging becomes necessary, though it's much more challenging. So far, direct imaging has mostly been successful with large, young exoplanets that shine brightly in infrared light.

With the advent of the ELT and other giant ground-based telescopes like the Thirty Meter Telescope (TMT) and the Giant Magellan Telescope (GMT), astronomers have high hopes for overcoming these challenges. The study, led by researchers from Ohio State University, simulated how well the ELT’s instruments might perform in detecting biosignatures like molecular oxygen, carbon dioxide, methane, and water on nearby exoplanets. The results were promising, particularly for certain exoplanets like GJ 887b, where the ELT's capabilities outshone those of current instruments.

However, the study also highlighted some limitations. For instance, the ELT might struggle with the TRAPPIST-1 system, a group of seven rocky planets with at least three in the habitable zone. The JWST is already finding it difficult to gather sufficient data on these planets, and the ELT may face similar challenges due to the "atmospheric seeing limitations" that affect ground-based telescopes.

In the coming years, the ELT and the JWST will continue to push the boundaries of exoplanet science, but they won't be the final word. The latest decadal survey for astronomy has recommended accelerating the development of a new, even more advanced space telescope to be launched in the 2040s. This future telescope, with an eight-meter mirror, would be optimized to detect and characterize rocky exoplanets in habitable zones, potentially bringing us closer to answering the age-old question of whether we are alone in the universe.

For more insights, you can explore further details in the published study in The Astronomical Journal.