Pluto has an underground ocean kept warm by a layer of gassy ice

[Judi Lynn]

SPACE 20 May 2019



What’s beneath the surface?
NASA/JHUAPL/SwRI
By Leah Crane

We think that Pluto is hiding a liquid ocean, but why it hasn’t frozen is a big mystery. Now it seems that gas trapped inside the bottom layer of its icy outer shell may be keeping it warm.

A number of observations point towards an underground ocean on Pluto, including deep cracks on its surface that seem to come from subsurface water freezing and expanding. But unlike other subsurface ocean worlds in our solar system, such as the icy moons Europa and Enceladus, Pluto is not stretched and warmed by the gravitational pull of a larger nearby object, meaning its ocean should be frozen.

To solve this puzzle, we need to figure out how Pluto is trapping the small amount of heat from the decay of radioactive elements in its rocky core. Francis Nimmo at the University of California, Santa Cruz and his colleagues have proposed that an extra layer between the ocean and the shell would do the trick.

The layer would be made out of a material called a gas hydrate, which occurs when gas molecules get trapped between frozen water molecules. “It’s not bubbles, it’s a little microscopic cage for keeping gas atoms in,” says Nimmo. “It doesn’t look very different from regular ice, but it’s got all that gas in there.”

More:
https://www.newscientist.com/article/2203696-pluto-has-an-underground-ocean-kept-warm-by-a-layer-of-gassy-ice/

[Javaman]

1. Gassy Ice was the name of my Rush cover band. nt