Abstract
Jupiter’s magnetic field is tilted by ~10º; with respect
to the planet’s spin axis, and as a result the Jovian plasma sheet
passes over the Galilean satellites at the jovigraphic equator twice per
planetary rotation period. The plasma and magnetic field conditions near
Ganymede’s magnetosphere therefore change dramatically every
~5 hours, creating a unique magnetosphere-magnetosphere
interaction, and on longer time scales as evidenced by orbit-to-orbit
variations. In this paper we summarize the typical magnetic field
conditions and their variability near Ganymede’s orbit as observed by
the Galileo and Juno spacecraft. We fit Juno data from orbit 34, which
included the spacecraft’s close Ganymede flyby in June 2021, to a
current sheet model and show that the magnetospheric conditions during
orbit 34 were very close to the historical average. Our results allow us
to infer the upstream conditions at the time of the Juno Ganymede flyby.