Jena 2013 – scientific programme

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EP: Fachverband Extraterrestrische Physik

EP 5: Erdnaher Weltraum und Planeten

EP 5.5: Talk

Wednesday, February 27, 2013, 18:00–18:15, HS 9

Mapping Ganymede's Time Variable Aurora in the Search for a Subsurface Ocean — •Joachim Saur¹, Stefan Duling¹, Lorenz Roth¹, Paul Feldman², Darrell Strobel², Kurt Retherford³, Melissa McGrath⁴, Fabrizio Musacchio¹, and Alexandre Wennmacher¹ — ¹University of Cologne — ²Johns Hopkins University — ³Southwest Research Institute — ⁴NASA, Marschall Space Flight Center

We present results of Hubble Space Telescope (HST) observations of Ganymede's auroral ovals when Ganymede was located at eastern elongation. The observations were obtained on November 19, 2010 and October 1, 2011 and cover five consecutive orbits of HST each. They were designed such that the Jovian magnetic latitudes of Ganymede span the entire possible range, i.e. Ganymede is exposed to the maximum variability of Jupiter's magnetospheric field during each visit. Our analysis shows that the auroral ovals only weakly rock in concert with the time-variable Jovian magnetic field. This weak rocking of the ovals is consistent with shielding of the time-variable field due to electromagnetic induction in a saline subsurface ocean on Ganymede.