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Published September 22, 2023 | v1
Journal Article Open

The distribution of CO₂ on Europa indicates an internal source of carbon

  • 1. ROR icon California Institute of Technology


Jupiter's moon Europa has a subsurface ocean, the chemistry of which is largely unknown. Carbon dioxide (CO₂) has previously been detected on the surface of Europa, but it was not possible to determine whether it originated from subsurface ocean chemistry, was delivered by impacts, or was produced on the surface by radiation processing of impact-delivered material. We mapped the distribution of CO₂ on Europa using observations obtained with the James Webb Space Telescope (JWST). We found a concentration of CO₂ within Tara Regio, a recently resurfaced terrain. This indicates that the CO₂ is derived from an internal carbon source. We propose that the CO₂ formed in the internal ocean, although we cannot rule out formation on the surface through radiolytic conversion of ocean-derived organics or carbonates.

Copyright and License

© 2023 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.


This study was based on observations made with the NASA/ESA/CSA James Webb Space Telescope (JWST). The data were obtained from the Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy under NASA contract NAS 5-03127 for JWST. The authors gratefully acknowledge H. Hammel and the JWST GTO #1250 team led by G. Villanueva for developing the Europa observing program and providing it to the community with no exclusive-access period.


S.K.T. is funded by Heising-Simons Foundation 51 Pegasi b postdoctoral fellowship 2021-2663.


S.K.T. performed the analysis, led the interpretation, and wrote the manuscript. M.E.B. reduced the JWST data, contributed to the interpretation, and aided in manuscript writing.

Data Availability

The JWST data are available at MAST https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html under program ID 1250. We also used (9) data from proposal ID 1538 for calibration (52). Our data reduction code is archived at Zenodo (53).

Conflict of Interest

The authors declare that they have no competing interests.


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Additional details

October 18, 2023
October 18, 2023