Energetic Ion Losses Observed During Juno's Close Encounter With Europa

Abstract We present energetic ion observations made by Juno during its close Europa flyby on 29 September 2022. These data show significant reductions in the ion intensities occurring in the moon's geometric wake region. The most significant losses occur for locally mirroring ions with gyrophases on the anti‐Jovian facing side of the wake. Ions with pitch angles >30° from the local perpendicular direction have guiding center trajectories that allow them to skip over the moon as they azimuthally drift with velocities ∼100 km s −1 . In general, short bounce times and large gyroradii can act as good indicators when to expect significant losses; however, we show asymmetries in energy, pitch angle, and gyrophase that we cannot fully explain and require detailed particle tracing with realistic electromagnetic fields. Finally, we compute ion integral fluxes along Juno's trajectory and show ∼85% of the near equatorially mirroring, >50 keV, ions are absorbed by Europa.

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Publication Details

Journal
Geophysical Research Letters
Published
2025-11-03
DOI
https://doi.org/10.1029/2024gl113100
Citations
2
Primary Topic
Astro and Planetary Science
Type
article
Field-Weighted Citation Impact
2.31

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article

Energetic Ion Losses Observed During Juno's Close Encounter With Europa

C. Paranicas, P. Kollmann, B. H. Mauk, N. Krupp et al.
2 citations
Geophysical Research Letters
Astro and Planetary Science
2.31
article

Energetic Ion Losses Observed During Juno's Close Encounter With Europa

C. Paranicas, P. Kollmann, B. H. Mauk, N. Krupp, F. Allegrini, Tom Nordheim, Leonardo Regoli, H. T. Smith, R. W. Ebert, Hans Huybrighs, S. J. Bolton, J. R. Szalay, G. Clark
article en
2 citations

Abstract

Abstract We present energetic ion observations made by Juno during its close Europa flyby on 29 September 2022. These data show significant reductions in the ion intensities occurring in the moon's geometric wake region. The most significant losses occur for locally mirroring ions with gyrophases on the anti‐Jovian facing side of the wake. Ions with pitch angles >30° from the local perpendicular direction have guiding center trajectories that allow them to skip over the moon as they azimuthally drift with velocities ∼100 km s −1 . In general, short bounce times and large gyroradii can act as good indicators when to expect significant losses; however, we show asymmetries in energy, pitch angle, and gyrophase that we cannot fully explain and require detailed particle tracing with realistic electromagnetic fields. Finally, we compute ion integral fluxes along Juno's trajectory and show ∼85% of the near equatorially mirroring, >50 keV, ions are absorbed by Europa.

Geophysical Research LettersVol. 52(21)
Southwest Research Institute (US), Dublin Institute For Advanced Studies (IE), Princeton University (US), Johns Hopkins University Applied Physics Laboratory (US), Max Planck Institute for Solar System Research (DE), The University of Texas at San Antonio (US)
National Aeronautics and Space Administration, Southwest Research Institute
Openalex Percentile: Top 10%
Astro and Planetary Science
2.31
DOIOpen Access PDFOpenAlex
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