Updated Spherical Harmonic Magnetic Field Moments of Ganymede From the Juno Flyby

In this study, we use data from the Juno and Galileo spacecraft to analyze the internal magnetic dynamo of Ganymede. As the only known moon with a strong internal magnetic field, Ganymede is a uniquely interesting object in the context of understanding the formation and structure of planetary magnetospheres. Using a spherical harmonic model centered on the moon, we report a dipole approximation for Ganymede of g01=-716.4 ${g}_{0}<^>{1}=-716.4$ nT, g11=56.0 ${g}_{1}<^>{1}=56.0$ nT, and h11=27.0 ${h}_{1}<^>{1}=27.0$ nT. We find that using a quadrupole fit rather than a dipole fit provides only a marginal increase in accuracy and instead favor the use of a dipole approximation until more data can be obtained. The magnetic moment estimates provided here can be used as a baseline for interpreting data from future spacecraft flybys of the moon, and can serve as inputs into numerical models studying Ganymede's magnetosphere.

Automated summary

In this study, we analyzed the internal magnetic dynamo of Ganymede using data from the Juno and Galileo spacecraft. Ganymede, the only known moon with a strong internal magnetic field, is of unique interest in understanding planetary magnetospheres. Our findings suggest that a dipole approximation is more accurate than a quadrupole fit. The estimated magnetic moments can be used as a baseline for interpreting future spacecraft data and for numerical modeling of Ganymede's magnetosphere.