title: Evidence of a global magma ocean in Io's interior.
abstract: Extensive volcanism and high-temperature lavas hint at a global magma reservoir in Io, but no direct evidence has been available. We exploited Jupiter's rotating magnetic field as a sounding signal and show that the magnetometer data collected by the Galileo spacecraft near Io provide evidence of electromagnetic induction from a global conducting layer. We demonstrate that a completely solid mantle provides insufficient response to explain the magnetometer observations, but a global subsurface magma layer with a thickness of over 50 kilometers and a rock melt fraction of 20% or more is fully consistent with the observations. We also place a stronger upper limit of about 110 nanoteslas (surface equatorial field) on the dynamo dipolar field generated inside Io.
authors.affiliation: Institute of Geophysics and Planetary Physics, University of California at Los Angeles, Los Angeles, CA 90095, USA. kkhurana@igpp.ucla.edu
authors.forename: Krishan K
authors.initials: KK
authors.lastname: Khurana
authors.forename: Xianzhe
authors.initials: X
authors.lastname: Jia
authors.forename: Margaret G
authors.initials: MG
authors.lastname: Kivelson
authors.forename: Francis
authors.initials: F
authors.lastname: Nimmo
authors.forename: Gerald
authors.initials: G
authors.lastname: Schubert
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Russell