- Original Caption Released with Image:
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Scientists are all but certain that Europa has an ocean underneath its icy
surface, but they do not know how thick this ice might be. This artist
concept illustrates two possible cut-away views through Europa's ice
shell. In both, heat escapes, possibly volcanically, from Europa's rocky
mantle and is carried upward by buoyant oceanic currents. If the heat from
below is intense and the ice shell is thin enough (left), the ice shell
can directly melt, causing what are called "chaos" on Europa, regions of
what appear to be broken, rotated and tilted ice blocks. On the other
hand, if the ice shell is sufficiently thick (right), the less intense
interior heat will be transferred to the warmer ice at the bottom of the
shell, and additional heat is generated by tidal squeezing of the warmer
ice. This warmer ice will slowly rise, flowing as glaciers do on Earth,
and the slow but steady motion may also disrupt the extremely cold,
brittle ice at the surface. Europa is no larger than Earth's moon, and its
internal heating stems from its eccentric orbit about Jupiter, seen in the
distance. As tides raised by Jupiter in Europa's ocean rise and fall, they
may cause cracking, additional heating and even venting of water vapor
into the airless sky above Europa's icy surface. (Artwork by Michael
Carroll.)
- Image Credit:
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NASA/JPL
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