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Published July 21, 2023 | v1
Journal Article Open

Hydrogen peroxide at the poles of Ganymede


Ganymede is the only satellite in the solar system known to have an intrinsic magnetic field. Interactions between this field and the Jovian magnetosphere are expected to funnel most of the associated impinging charged particles, which radiolytically alter surface chemistry across the Jupiter system, to Ganymede's polar regions. Using observations obtained with JWST as part of the Early Release Science program exploring the Jupiter system, we report the discovery of hydrogen peroxide, a radiolysis product of water ice, specifically constrained to the high latitudes. This detection directly implies radiolytic modification of the polar caps by precipitation of Jovian charged particles along partially open field lines within Ganymede's magnetosphere. Stark contrasts between the spatial distribution of this polar hydrogen peroxide, those of Ganymede's other radiolytic oxidants, and that of hydrogen peroxide on neighboring Europa have important implications for understanding water-ice radiolysis throughout the solar system.

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. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC). https://creativecommons.org/licenses/by-nc/4.0/


This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with program #1373, which is led by co-PIs (principal investigators) Imke de Pater and Thierry Fouchet and has a zero-exclusive-access period.


S.K.T. was supported by a Heising-Simons Foundation 51 Pegasi b postdoctoral fellowship (2021-2663). L.N.F. was supported by a European Research Council Consolidator Grant (under the European Union's Horizon 2020 research and innovation programme, grant agreement no. 723890) at the University of Leicester. I.d.P. and M.H.W. were in part supported by the Space Telescope Science Institute grant no. JWST-ERS-01373.


S.K.T. performed the analysis, led the interpretation, and wrote the manuscript. M.E.B. reduced the JWST data and aided in interpretation and manuscript writing. I.d.P. and T.F. are the co-PIs of the Director's Discretionary Early Release Science (DD-ERS) proposal on the Jovian system that obtained the data. M.H.W., D.B.-M., L.N.F., K.d.K., E.L., O.P., M.R.S., and M.S.T. all contributed substantially to the planning and definition of the resulting observations. P.R.-O. contributed to the reduction of the Ganymede JWST observations. E.Q., F.T., S.C., and A.M. contributed helpful comments, interpretations, and expertise during manuscript preparation.

Data Availability

The data used in this work are available at the NASA Mikulski Archive for Space Telescopes (https://archive.stsci.edu/) under program #1373. All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials.

Conflict of Interest

The authors declare that they have no competing interests.


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Additional details

September 7, 2023
September 7, 2023