Overview
- The University of Michigan–led study, published Thursday, April 23, reports deuterated water in 3I/ATLAS at about 30 times the level of solar-system comets and 40 times the ratio in Earth’s oceans.
- Deuterium builds up only in ultra-cold conditions, so the measured ratio points to formation below roughly 30 kelvin in a low-radiation region such as a prestellar cloud or the far outer disk of a young star.
- Researchers used the Atacama Large Millimeter/submillimeter Array to separate heavy water from ordinary water shortly after the comet’s October 29, 2025 perihelion, with early gas detections from the MDM Observatory, marking the first such reading on an interstellar object.
- The European Space Agency estimated the comet released water equal to about 70 Olympic swimming pools per day near the Sun, providing a rich sample of vapor for chemical analysis.
- Independent teams using NASA’s James Webb Space Telescope have reported signs of deuterium in preprints that support the finding, though those JWST results have not yet been peer-reviewed.