Debris disks are young planetary systems filled with planets, asteroids, comets, and tiny dust particles. Water ice, the most common frozen substance, is crucial for forming planets and smaller bodies. While ice has been found in Kuiper Belt objects and comets in our Solar System, scientists have yet to confirm its presence in debris disks.
A new study report about discovering water ice in the HD 181327 debris disk using the near-infrared spectrograph onboard the James Webb Space Telescope.
Scientists used NASA’s James Webb Space Telescope to confirm crystalline water ice in a dusty debris disk around a Sun-like star 155 light-years away. In 2008, NASA’s retired Spitzer Space Telescope had suggested the possibility of frozen water there.
Webb’s data revealed not just ordinary ice but crystalline water ice—the same type in Saturn’s rings and Kuiper Belt objects. This ice is mixed with fine dust throughout the disk, forming tiny “dirty snowballs.”
Water on Earth is even older than our Sun
Astronomers have waited decades for this confirmation. Christine Chen, an astronomer at the Space Telescope Science Institute, recalls her advisor predicting ice in debris disks 25 years ago—but until Webb, telescopes weren’t sensitive enough to detect it.
Water ice is crucial in forming giant planets and can be delivered to rocky worlds by comets and asteroids. Now that Webb has confirmed its presence, scientists can explore how ice shapes planetary systems across the cosmos.
HD 181327, a young, hot star about 23 million years old, is larger and more massive than our Sun. Its system includes a wide dust-free gap, with a distant debris disk resembling our Kuiper Belt—home to dwarf planets and icy objects.
Astronomers believe our Kuiper Belt once looked similar to this star’s disk. Ongoing collisions among icy bodies release tiny, dusty ice particles just the right size for Webb to detect.
New link between water and planet formation revealed
Water ice in this system isn’t evenly distributed. Most of it—over 20%—is found in the debris disk’s coldest outer regions. Moving inward, Webb detected only about 8% water ice, where frozen particles likely form faster than they break down. Closer to the star, almost no ice remains, likely due to intense ultraviolet radiation vaporizing it or planetesimals locking it inside.
Scientists will continue exploring how water ice influences planetary formation across the Milky Way. It plays a key role in shaping worlds and possibly delivering water to emerging rocky planets.
Scientists used Webb’s NIRSpec (Near-Infrared Spectrograph) to study HD 181327. This powerful tool can detect incredibly faint dust particles—something only possible from space.
The James Webb Space Telescope is the most advanced space observatory. It is uncovering secrets of our solar system, scanning distant exoplanets, and exploring the origins of the universe itself. Its discoveries are reshaping our understanding of cosmic evolution.
Journal Reference:
- Xie, C., Chen, C.H., Lisse, C.M. et al. Water ice in the debris disk around HD 181327. Nature 641, 608–611 (2025). DOI: 10.1038/s41586-025-08920-4
