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- Title
Updated Spherical Harmonic Magnetic Field Moments of Ganymede From the Juno Flyby.
- Authors
Weber, Tristan; Moore, Kimberly; Connerney, John; Espley, Jared; DiBraccio, Gina; Romanelli, Norberto
- 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 ${g}_{0}^{1}=-716.4$ 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. Plain Language Summary: Jupiter's moon Ganymede is the only known moon to possess its own strong internal magnetic field. This makes it a uniquely interesting planetary body in the context of understanding how planetary magnetic fields in the solar system form and interact with the space environment. Juno's recent flyby of the moon has provided us with a new set of spacecraft data from Ganymede for the first time in 20 years, and using that data, we calculated a new best estimate of the properties of the moon's internal field. This estimate can be used as a baseline for future studies of Ganymede using data and numerical simulations. Key Points: Using data from Juno's orbit 34 flyby of Ganymede, we present updated spherical harmonic moments of the moon's internal magnetic fieldGanymede's dipole moment is very dominant, with quadrupole moments that are over a factor of 10 weaker than the main dipole termWe find a quadrupole fit to be unjustified, strengthening previous arguments that deviations from a dipole are due to induction signatures
- Subjects
GALILEI, Galileo, 1564-1642; MAGNETIC moments; MAGNETIC fields; SPACE environment; SOLAR magnetic fields; QUADRUPOLE moments; JUPITER (Planet); LAGRANGIAN points
- Publication
Geophysical Research Letters, 2022, Vol 49, Issue 23, p1
- ISSN
0094-8276
- Publication type
Article
- DOI
10.1029/2022GL098633