Abstract
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 nT, g11 = 56.0 nT, and h11 = 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.