Distribution of rock, metals, and ices in Callisto. 69–70 (San Juan Capistrano Research Inst., San Juan Capistrano, CA, (1996)).Īnderson, J. Salts on Europa's surface detected by Galileo's Near Infrared Mapping Spectrometer. Creep of water ices at planetary conditions: a compilation. Tidal heating in an internal ocean model of Europa. Liquid water and active resurfacing on Europa. Is there liquid water on Europa? Geophys. Thermal evolution of a differentiated Ganymede and implications for surface features. On the internal structure of the major satellites of the outer planets. Europa's differentiated internal structure: inferences from four Galileo encounters. Arizona Press, Tucson, (1986)).Īnderson, J. Magnetic fields and the detectability of brine oceans in Jupiter's icy satellites. in American Institute of Physics Handbook 125–127 (McGraw Hill, New York, (1963)).Ĭolburn, D. The subalfvénic interaction of the Galilean satellites with the Jovian magnetosphere. The ionosphere of Europa from Galileo radio occultations. Europa's oxygen exosphere and its magnetospheric interaction. Ultra low frequency MHD waves in Jupiter's middle magnetosphere. The lunar wake at 6.8 RL: WIND magnetic field observations. Nonlinear standing Alfvén wave current system at Io: Theory. Introduction to Geomagnetism 308–340 (Scottish Academic, Edinburgh, (1993)). Geological evidence for solid-state convection in Europa's ice shell. Evidence for a subsurface ocean on Europa. Amagnetic signature at Io: initial report from the Gallileo magnetometer. Discovery of Ganymede's magnetic field by the Galileo spacecraft. Absence of an internal magnetic field at Callisto. Europa's magnetic signature: report from Galileo's first pass on December 19, 1996. 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 5, 6 in the case of Europa. 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 interpret these perturbations as arising from induced magnetic fields, generated by the moons in response to the periodically varying plasma environment. Here we report perturbations of the external magnetic fields (associated with Jupiter's inner magnetosphere) in the vicinity of both Europa and Callisto. Initial results from the spacecraft's magnetometer 1, 2 have indicated that neither Europa nor Callisto have an appreciable internal magnetic field, in contrast to Ganymede 3 and possibly Io 4. The findings were published in the journal Geophysical Research Letters.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. When the tides generated by other objects in Jupiter’s moon system match each moon’s own resonant frequency, the moon begins to experience more heating than that due to tides raised by Jupiter alone, and in the most extreme cases, this could result in the melting of ice or rock internally. Hay said.Įach moon’s natural frequency depends on the depth of its ocean, as per reports. “It’s surprising because the moons are so much smaller than Jupiter,” Dr. “Ultimately, we want to understand the source of all this heat, both for its influence on the evolution and habitability of the many worlds across the solar system and beyond.” “Io, the moon closest to Jupiter, shows widespread volcanic activity, another consequence of tidal heating, but at a higher intensity likely experienced by other terrestrial planets, like Earth, in their early history.” Antony Trinh, a postdoctoral researcher in the Lunar and Planetary Laboratory at the University of Arizona. “Maintaining subsurface oceans against freezing over geological times requires a fine balance between internal heating and heat loss, and yet we have several pieces of evidence that Europa, Ganymede, Callisto and other moons should be ocean worlds,” said co-author Dr. Hamish Hay of NASA’s Jet Propulsion Laboratory and colleagues found that moon-moon interactions may be more responsible for the heating than Jupiter alone, as reported by. The researchers believe that Jupiter was responsible for most of the tidal heating associated with the liquid interiors of the moons.
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