|
Europa may be frozen solid on the surface, but planetary scientists have known for years that the Europan interior is heated by tidal flexing, a process fueled by the gravitational forces felt from the enormous pull of Jupiter and other neighboring moons. This heating, though not as apparent as on Europa's sister moon Io, appears to cause inner layers of Europa to remain liquefied rather than solid.
Now, after analyzing their most recent data on Europa's interior, researchers at the University of California at Los Angeles have concluded that Europa's magnetic field oscillates or flip-flops, a property that could only be explained by a layer of some electrically conductive material. Though the possibility of some other conductive material, such as a carbon-rich material like graphite, is not completely out of the question, scientists say that liquid water – or possibly even slushy watery ice – is the most logical answer.
"One can more easily imagine that there's a salty ocean than another exotic material that could give you this kind of conductivity," said Krishan Khurana, one of the lead investigators on this latest Europa find. "In terms of plausibility, an ocean is the most likely scenario."
Khurana and his colleagues first realized they might be looking at the possibility of a global Europan ocean two years ago, when they stumbled on an odd signature in Europa's magnetic field during an earlier Galileo flyby. Though the one pass provided only a brief glimpse, it appeared that Europa's magnetic field might be flipping regularly due to the influences of planet Jupiter's strong magnetic field an occurrence; which could only be explained by a thick conductive layer several miles (kilometers) below the surface.
