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Induced magnetic fields as evidence for subsurface oceans in Europa and Callisto

Khurana, K. K. and Kivelson, M. G. and Stevenson, D. J. and Schubert, G. and Russell, C. T. and Walker, R. J. and Polanskey, C. (1998) Induced magnetic fields as evidence for subsurface oceans in Europa and Callisto. Nature, 395 (6704). pp. 777-780. ISSN 0028-0836. doi:10.1038/27394.

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The Galileo spacecraft has been orbiting Jupiter since 7 December 1995, and encounters one of the four galilean satellites—Io, Europa, Ganymede and Callisto—on each orbit. Initial results from the spacecraft's magnetometer, have indicated that neither Europa nor Callisto have an appreciable internal magnetic field, in contrast to Ganymede and possibly Io. Here we report perturbations of the external magnetic fields (associated with Jupiter's inner magnetosphere) in the vicinity of both Europa and Callisto. We interpret these perturbations as arising from induced magnetic fields, generated by the moons in response to the periodically varying plasma environment. Electromagnetic induction requires eddy currents to flow within the moons, and our calculations show that the most probable explanation is that there are layers of significant electrical conductivity just beneath the surfaces of both moons. We argue that these conducting layers may best be explained by the presence of salty liquid-water oceans, for which there is already indirect geological evidence, in the case of Europa.

Item Type:Article
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URLURL TypeDescription
Khurana, K. K.0000-0002-2856-1171
Kivelson, M. G.0000-0003-3859-8581
Stevenson, D. J.0000-0001-9432-7159
Russell, C. T.0000-0003-1639-8298
Additional Information:© 1998 Macmillan Publishers Ltd. Received 24 June; accepted 14 August 1998. We thank D. Bindschadler of the Jet Propulsion Laboratory for support in all phases of data collection and J. Mafi for data processing and preparation of data plots. This work was partially supported by the Jet Propulsion Laboratory.
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Issue or Number:6704
Record Number:CaltechAUTHORS:20130703-135138131
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:39230
Deposited By: Tony Diaz
Deposited On:06 Aug 2013 20:10
Last Modified:09 Nov 2021 23:43

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