I heard a statement that Europa has oceans - greater than the earth’s oceans put together! Apparently, Europa is known to have underwater* volcanoes, too. I am just wondering: What keeps the ocean liquid? It can only be the heat from below the surface, correct? Surely at that distance from the sun, it cannot be solar heat! - Jinx
You’re right. The oceans are solid at the surface, solar heat being ineffective at melting water so far from the sun and at those exposure times.
IIRC, it is currently believed that volcanism and possibly the friction of tidal forces from Jupiter (not mutually exclusive, BTW) provide enough heat to keep oceans liquid, and heat is retained relatively well beneath ice.
The internal heat of Europa would be created by tidal forces from Jupiter. The intense gravity from the planet would stretch and squeeze the moon, creating internal heat enough to keep the oceans in a liquid state.
Europa is covered with ice – lots of ice. It’s believed by planetologists that either (a) that ice goes all the way down to the rock surface, several dozen kilometers down – the minority view; or (b) that ice covers oceans of liquid water.
If there is water, the combination of the small amount of interior heating present from radioactive isotopes breaking down (which is the principal source of the Earth’s internal heat) with the stress energy caused by Jupiter and the Sun’s gravitational pull (there’s a better way to say that, I’m sure, but I trust that will bring it across) is the heat source keeping subsurface Europa at liquid water temperatures. (Don’t forget that ice is an excellent insulator, too – the heat won’t radiate away through it.)
and make no mistake–we’re talking water oceans, here.
and that could mean Life.
I get excited every time I think of it! 
Sssh!!!
Don’t you guys remember the whole “All these worlds are yours, except Europa…” thing?
Do you want to end up with a monolith dropped on your head? Or get stuck in weird fetus jail?
:eek:
A tangential question (a.k.a. an hijack): does the energy that is derived through tidal forces mean that Europa is slowing down and will eventually crash into Jupiter? If so, does it have long left?
It’s probably the other way around!
(At least that’sthe way it works here. The tidal effects we see on Earth effectively add energy to the moon, by slowing down the rotation of the Earth and pushing the moon to a higher orbit.
By analogy, the interaction between Jupiter and Europa ought to slow down the spining of Europa {and ever so slightly increase the orbit and slow down the spinning of Jupiter [Assuming Jupiter spins in the same direction as Europas orbt - otherwise it’d be the other way round.] } )
Just an aside I saw a NASA group on Junkyard Wars a few years ago and they were working on a project to send a submarine to Europa.
It would drill through the ice and explore the water underneath.
I assume it’s all on paper, and have no idea if the group exists anymore.
MtM
That explains why your sig line is so large.