Diagnosing the Atmosphere of Jupiter's Volcanic Moon Io Using Energetic Neutral Atoms (ENAs)

Abstract During a Juno spacecraft encounter with Jupiter's volcanic moon Io (30 December 2023), the Jupiter Energetic Particle Detector Instrument (JEDI) observed Energetic Neutral Atoms (ENAs) of >150 keV oxygen and sulfur (O + S) coming from Io's mostly nightside atmosphere. JEDI line...

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Main Authors: B. H. Mauk, H. T. Smith, R. E. Johnson, V. Dols, F. Bagenal, J. E. P. Connerney, S. J. Bolton, G. Clark, D. K. Haggerty, P. Kollmann, C. P. Paranicas
Format: Article
Language:English
Published: Wiley 2025-03-01
Series:Geophysical Research Letters
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Online Access:https://doi.org/10.1029/2024GL112668
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Summary:Abstract During a Juno spacecraft encounter with Jupiter's volcanic moon Io (30 December 2023), the Jupiter Energetic Particle Detector Instrument (JEDI) observed Energetic Neutral Atoms (ENAs) of >150 keV oxygen and sulfur (O + S) coming from Io's mostly nightside atmosphere. JEDI lines‐of‐sight approached closest to Io between 1.31 and 1.49 Io radii (RIo), above the predominantly SO2 core atmosphere but imbedded within the extended atmosphere and corona of SO2, SO, O, and S. The ratio of O + S ENA intensities and O + S ion intensities estimated to be interacting with Io's atmosphere along JEDI lines‐of‐sight are 4%–7%. Those estimates are below expectations (∼11%–∼14%), but presently within uncertainties, based on integrations along the JEDI lines‐of‐sight through a prevailing but uncertain, local‐time‐symmetric model of Io's extended atmosphere. Expected ENA production rates will remain uncertain until detailed modeling of ion/atmosphere interactions are performed, and knowledge of charge exchange cross sections is verified.
ISSN:0094-8276
1944-8007