Life Beyond Earth: Searching for Signs in Exoplanet Atmospheres

NASA and scientists use telescopes such as the James Webb Space Telescope to analyze exoplanet atmospheres for gases linked to life, while studies of Earth’s extremophiles and the habitable zone help narrow the search.

So far, known life exists only on Earth, but scientists are actively searching for signs beyond our planet. The James Webb Space Telescope, launched in 2021, can observe the mix of gases in the atmospheres of Earth-sized exoplanets. Researchers look for combinations of gases that on Earth are associated with biology, and they study extreme Earth organisms and orbital conditions to guide where to look. Transit spectroscopy — splitting starlight into a spectrum as a planet passes in front of its star — is a primary method for reading atmospheric composition. Key facts: - The James Webb Space Telescope can use transit spectroscopy to measure the gases present in some exoplanet atmospheres. - Gases noted as potential biosignatures include oxygen, carbon dioxide, and methane, and specific combinations could suggest biological activity. - More than 5,800 exoplanets have been confirmed in our galaxy, while the true number of planets is likely much larger. - Scientists study extremophiles on Earth, organisms that thrive in extreme environments, as possible analogs for life elsewhere. - Other avenues include searching for life beneath the Martian surface, in Europa’s subsurface ocean, or indirect evidence of technology such as atmospheric pollution (technosignatures). Summary: Detecting atmospheric biosignatures would alter our understanding of life’s distribution, but such detections are likely to be expressed as probabilities rather than absolute proof. Continued observations with the James Webb Space Telescope and future missions will refine assessments of candidate worlds and their atmospheric compositions. The search combines atmospheric measurements, studies of Earth analogs, and improving telescope capabilities.