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Originally Posted by John Mendenhall
If Ganymede had a global liquid ocean which then froze, during the freezing the ice will first expand, and then contract, as the temperature drops. Certainly some astonishing cracking will result.
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Well no one has ever observed this alleged ocean and science is supposed to be about observation.
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If there is an occasional large impact, then there will be melting and re-freezing, perhaps moon-wide.
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Impacts cannot account for the amount of surface growth observed.
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There is plenty of room in conventional physics for modest expansion and contraction on Ganymede, given these conditions.
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Any room for immodest expansion?
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It's that, at least at present, we can't have a geologist walking around on the surface going "Oh, I see what happened!"
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We don't need to because we have photographs.