These drawings depict two proposed models of the subsurface structure of Jupiter's moon Europa. No conclusive proof has yet been found that an ocean exists on Europa, but geologic features on its surface, imaged by NASA's Galileo spacecraft, might be explained either by the existence of a warmer, convecting ice layer, located several kilometers below a cold, brittle surface ice crust (top model), or by a layer of liquid water with a possible depth of more than 100 kilometers (bottom model). If an ocean 100 kilometers (or 60 miles) deep existed below a Europan ice crust 15 kilometers (10 miles) thick, it would be 10 times deeper than any ocean on the earth and would contain twice as much water as the earth's oceans and rivers combined.
[back]
|
