JWST Finds No Earthlike Atmosphere on TRAPPIST-1 d

The James Webb Space Telescope found no Earthlike atmosphere on TRAPPIST-1 d, narrowing the path for finding a nearby Earth twin and guiding how we study atmospheres around red dwarfs.

TRAPPIST-1 d Atmosphere Clarity Dims Hopes for Earthlike Habitability

NASA's James Webb Space Telescope observed TRAPPIST-1 d during two transits in 2022 and built a transmission spectrum in the 0.6 to 5.2 micron range. The data show a flat spectrum with no detectable atmospheric features, a result that argues against an Earthlike atmosphere and water vapor signature. The planet sits near the inner edge of the system's habitable zone, and the team concludes that a thick hydrogen rich atmosphere or a clear water rich atmosphere is unlikely. The results, published in The Astrophysical Journal, narrow the field for what kind of atmosphere TRAPPIST-1 d could possess and point to several alternative explanations such as an extremely thin atmosphere or high altitude clouds.

Beyond TRAPPIST-1 d, the study notes that the outer planets in the same system, TRAPPIST-1 e, f, g, and h, might still keep substantial atmospheres, or water, even if d is airless. But these outer worlds are colder and fainter targets for JWST, and the absence of a complete spectrum leaves room for future observation. The work highlights the uncertainty around red dwarf planets: frequent flares can erode atmospheres, yet magnetic fields and atmospheric chemistry could shield some worlds. Webb's infrared sensitivity is enabling the first detailed look at Earth sized planets around red dwarfs, reshaping expectations about what counts as a habitable world.

The finding underscores a stubborn truth about exoplanet habitability. A planet being in the habitable zone is not a guarantee of an Earthlike atmosphere. Scientists must test atmospheric composition directly, and JWST's results push researchers to refine models of how red dwarf activity shapes atmospheres. The article also shows how science evolves: a single measurement narrows possibilities and sparks a new round of questions.

This work also reveals how the public conversation about space remains hopeful but cautious. Technology can expand what we can test, yet it also forces a careful rethinking of what makes a world livable. The hunt for life beyond Earth is not a single discovery but a process of mapping boundaries, and these results move that map forward in small, precise steps.

Highlights

The search for life beyond Earth continues with a measured pace and a sharper map of what remains possible.