Ionosphere-magnetosphere coupling studies with Juno and Cassini proximal orbits

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Abstract

The magnetodisk of Jupiter is dragged into partial cororation with the planet by an electric current loop that connects the disk to the jovian upper atmosphere via intense field-aligned currents driving the main auroral emissions. Thanks to its unique orbital geometry, Juno will allow for the first time a quantitative study of the characteristics of the three key segments of this circuit and of their connection: the magnetodisk/plasmasheet, where currents transverse to the magnetic field maintain the disk into partial corotation; auroral field lines, which connect the magnetodisk to the auroral circuit proper and along which current is carried in part by accelerated particles; and the ionospheric closure of the circuit, where Ohmic currents extract momentum from the upper atmosphere and produce Joule heating. To a large extent, the Cassini proximal orbits will provide a similar opportunity at Saturn. 
We describe our detailed plans for a physical study of these three segments and their interconnections, and of the key processes that are at work in the enforcement of magnetospheric corotation and sub-corotation at Jupiter and Saturn, based on the outcome of a first workshop on “Magnetosphere-Ionosphere-Thermosphere coupling at Jupiter” organized in Toulouse by IRAP and LESIA on oct. 13 and 14, 2015. All contributions to this workshop can be found on line at:
http://cdpp.eu/workshops/Jupiter_MIT_coupling/
Extension of this work to a broader circle of the PNST community, in view of its consolidation and deepening in support to the on-going Juno and Cassini missions and in preparation for the upcoming missions to the Jupiter system, JUICE and Europa, is very welcome! Collaborative, multi-laboratory proposals in the ANR and ERC frameworks to develop this work line are anticipated.