In a groundbreaking study, a team of researchers led by Matthew Belyakov from the California Institute of Technology has made the first-ever spectroscopic characterization of an interstellar object at mid-infrared wavelengths. The team, which includes Ian Wong, Bryce T. Bolin, M. Ryleigh Davis, Steven J. Bromley, Carey M. Lisse, and Michael E. Brown, utilized the James Webb Space Telescope’s Mid-Infrared Instrument (JWST/MIRI) to observe the interstellar comet 3I/ATLAS.
The researchers obtained spectra of 3I/ATLAS on December 15-16 and December 27, 2025, when the object was at heliocentric distances of 2.20 and 2.54 astronomical units, respectively. Their observations revealed fluorescence features from several gaseous species, including water, carbon dioxide, and atomic nickel. Notably, they also reported the first direct detection of methane in an interstellar object. The delayed onset of methane production relative to water suggests that the outermost layers of the comet may have been depleted of methane in the past, with the observed methane emerging from unprocessed subsurface material.
The study found that the overall outgassing of the comet significantly reduced over a 12-day period, with water activity levels dropping more steeply than other species. Through near-nucleus coma mapping, the researchers confirmed that 3I continues to display an extended source of water production from icy grains entrained within the coma. The production rate measurements also revealed that 3I exhibits a strongly enhanced CO2:H2O mixing ratio relative to typical solar system comets, as well as a somewhat enriched CH4:H2O value.
This research, published in the prestigious journal Nature Astronomy, provides valuable insights into the composition and behavior of interstellar objects. For the energy industry, understanding the volatile inventory of such objects can offer clues about the chemical processes that occur in the interstellar medium and the early solar system. This knowledge could potentially inform the development of new energy technologies and the search for extraterrestrial resources. Moreover, the advanced spectroscopic techniques used in this study could be adapted for remote sensing applications in the energy sector, such as monitoring emissions and detecting leaks in pipelines and storage facilities.
This article is based on research available at arXiv.