https://www.egyptindependent.com/pluto-s-largest-moon-likely-fractured-sub-surface-ocean-nasa/
Pluto's largest moon likely fractured by sub-surface ocean: NASA - Egypt Independent
Feb 20, 2016 - Images from the New Horizon space probe suggest that Pluto's moon Charon once had a sub-surface ocean that has since frozen and expanded, causing the surface...
sub surface ocean