Europa Modifies Jupiter's Plasma Sheet

• Published in: Geophysical research letters Vol. 51; no. 6
• Main Authors: Szalay, J. R., Saur, J., McComas, D. J., Allegrini, F., Bagenal, F., Bolton, S. J., Ebert, R. W., Kim, T. K., Livadiotis, G., Poppe, A. R., Valek, P., Wilson, R. J., Zirnstein, E. J.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 28.03.2024; Wiley
• Subjects: Charged particles; Composition; Europa; Ganymede; Hydrogen; Hydrogen clouds; Icy satellites; Ions; Jupiter; Jupiter probes; Jupiter satellites; Oxygen; Planetary magnetospheres; Plasma; Protons; Spectrometry; Sulfur; Sulphur; Thermal plasmas
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2023GL105809

Jupiter's plasma sheet has been understood to be primarily composed of Io‐genic sulfur and oxygen, along with protons at lower mass density. These ions move radially away from Jupiter, filling its magnetosphere. The material in the plasma sheet interacts with Europa, which is also a source of magnetospheric pickup ions, primarily hydrogen and oxygen. Juno's thermal plasma instrument JADE, the Jovian Auroral Distributions Experiment, has provided comprehensive in situ observations of the composition of Jupiter's plasma sheet ions with its Time‐of‐Flight mass‐spectrometry capabilities. Here, we present observations of the magnetospheric composition in the Europa‐Ganymede region of Jupiter's magnetosphere. We find material from Europa is intermittently present at comparable densities to Io‐genic plasma. The intermittency of Europa‐genic signatures suggests Europa's neutral oxygen toroidal cloud is more localized to Europa's vicinity than its hydrogen cloud. These observations reveal a more complex and compositionally diverse magnetosphere than previously thought. Plain Language Summary Jupiter's charged particle environment is overwhelmingly driven by material lost from Io. This material interacts with the icy moon Europa, which can also inject charged particles into the environment. We find that Europa appreciably contributes to and modifies its local charged particle environment, revealing a more complex and compositionally diverse magnetosphere than previously thought. Key Points Three distinct heavy ion populations observed in Jupiter's plasma sheet: Io‐genic plasma, Europa‐genic plasma, and Io‐genic energetic particles The mixture of Io‐genic and Europa‐genic plasma varies greatly throughout the Europa‐Ganymede region We find evidence Europa's oxygen neutral toroidal clouds are more localized than its hydrogen cloud