Launch Catch-Up — Study Announced October 26, 2026
A Southwest Research Institute-led team said James Webb Space Telescope observations suggest that interstellar comet 3I/ATLAS releases tiny grains containing water ice mixed with dust.
The institute’s October 26 announcement describes findings from three observations between August 2025 and April 2026. The new development is the research report, rather than a new comet discovery or telescope observation.
Webb’s infrared instrument detected a strong water-ice feature near 3 microns, with weaker or missing features at shorter wavelengths. Researchers’ models favored dusty grains approximately a micron or smaller.
The team found similarities with water-ice spectra from some bodies beyond Neptune. That resemblance may offer clues about material from which planets form around other stars, the researchers said; it does not establish identical compositions or origins.
The grains also appeared to change over time. Researchers cannot yet distinguish whether heating by the Sun or newly exposed comet material explains the change. Further observations are needed to test the interpretation and determine whether this comet is typical.
Sources: Southwest Research Institute study announcement: https://www.swri.org/newsroom/press-releases/swri-led-study-uses-webb-compare-interstellar-comet-3i-atlas-icy-bodies-our-solar-system