Kivelson MG, Khurana KK, Walker RJ, Russell CT, Linker JA, Southwood DJ, Polanskey C
M. G. Kivelson, K. K. Khurana, R. J. Walker, C. T. Russell, Institute of Geophysics and Planetary Physics, University of California, Los Angeles, Los Angeles, CA 90095-1567, USA. J. A. Linker, Science Applications International Corporation, San Diego, CA 92171, USA. D. J. Southwood, Department of Physics, Imperial College of Science, Technology, and Medicine, London, SW7 2BZ, UK. C. Polanskey, Jet Propulsion Laboratory, Pasadena, CA 91109, USA.
Science. 1996 Jul 19;273(5273):337-40. doi: 10.1126/science.273.5273.337.
During the inbound pass of the Galileo spacecraft, the magnetometer acquired 1 minute averaged measurements of the magnetic field along the trajectory as the spacecraft flew by Io. A field decrease, of nearly 40 percent of the background jovian field at closest approach to Io, was recorded. Plasma sources alone appear incapable of generating perturbations as large as those observed and an induced source for the observed moment implies an amount of free iron in the mantle much greater than expected. On the other hand, an intrinsic magnetic field of amplitude consistent with dynamo action at Io would explain the observations. It seems plausible that Io, like Earth and Mercury, is a magnetized solid planet.
