EGU22-10783, updated on 16 May 2023
EGU General Assembly 2022
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Evidence for Magnetic Reconnection at Ganymede’s Upstream Magnetopause during the PJ34 Juno Flyby

Robert W. Ebert1,2, Frederic Allegrini1,2, NIgel Angold3, Fran Bagenal4, Scott J. Bolton1, Jack Connerney5,6, Gina DiBraccio6, Eric Fattig1, Stephen A. Fuselier1,2, Steve Levin7, David J. McComas3, Jake Montgomery2,1, Norberto Romanelli6, Jamey R. Szalay3, Phil Valek1, and Robert J. Wilson4
Robert W. Ebert et al.
  • 1Southwest Research Institute, Department of Space Research, San Antonio, Texas, USA (
  • 2University of Texas at San Antonio, San Antonio, Texas, USA
  • 3Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey, USA
  • 4Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, Colorado, USA
  • 5Space Research Corporation, Annapolis, Maryland, USA
  • 6NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
  • 7Jet Propulsion Laboratory, Pasadena, California, USA

Juno made a close flyby of Ganymede and flew through its magnetosphere on June 7, 2021. This flyby included a crossing of Ganymede’s upstream magnetopause on the outbound segment of the spacecraft transit. We present plasma and magnetic field observations near that magnetopause crossing from Juno’s Jovian Auroral Distributions Experiment (JADE; McComas et al. 2017) and magnetometer (MAG; Connerney et al. 2017), respectively. JADE observed enhanced electron fluxes, including heated, streaming electrons, some with bi-directional pitch angle distributions, as Juno crossed the magnetopause current layer (MCL) as identified by the magnetic field observations. The acceleration of cold ions, both protons and heavy ions originating from Ganymede, was observed on approach to the magnetopause along with a likely mixing of ions from Ganymede and Jupiter’s plasma sheet within the MCL. These observations are used to examine the physics of plasma interactions at this boundary, including evidence that magnetic reconnection, considered a key driver of magnetospheric dynamics at Ganymede, was occurring along the magnetopause at that time.

How to cite: Ebert, R. W., Allegrini, F., Angold, N., Bagenal, F., Bolton, S. J., Connerney, J., DiBraccio, G., Fattig, E., Fuselier, S. A., Levin, S., McComas, D. J., Montgomery, J., Romanelli, N., Szalay, J. R., Valek, P., and Wilson, R. J.: Evidence for Magnetic Reconnection at Ganymede’s Upstream Magnetopause during the PJ34 Juno Flyby, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10783,, 2022.