Touchdown on Titan

RedPlanet

Last night I went to a presentation at TCD by John Zarnecki, whom worked on the Huygens probe that landed on Titan a couple years ago.

One thing that really struck me was that he said one of the prevailing theories is that the crust of Titan's surface is thought to be bouyant, ontop of a think layer of liquid. And so is de-coupled from the rocky core.
http://en.wikipedia.org/wiki/File:Titan_cutaway.svg

Apparently surface features were observed (via Cassini satellite) to have possibly moved by as much as 30km and this required an explanation.

Was hoping to ask him a question but the night wore on a bit and so didn't get the opportunity.
But i was wondering, is this theory of Titan's bouyant surface unique?
Do any other planetary bodies do the same?

And, shouldn't we expect to see a lot of cryovolcanism due to the shifting crust?

The earth's crust moves, and we have a lot of resulant earthquakes as well as volcanoes. And our crust isn't shifting remotely like they say Titan's is.

Linguo

Hi There,

Lecture was brilliant, John's a great speaker.

Titan being decoupled from it's core is very interesting.

If I had read your post sooner I would have asked him!

There is a good deal of cryovolcanoes to account for the Argon 40 in atmosphere but I have no idea how many!

Linguo

Would Titan's rigid lithosphere have anything to do with the lack of cryovolcanoes? And less convection from the core?

Dr Pepper

Not sure if I can answer any of these complex questions but I was at the lecture too and it was the best one I've been at yet. Nice fella and very inspirational lecture!

At a pure guess, I'd imagine the decreased 'cryovolcanism' could be due to a general lack of friction between the crust and the liquid layer below it (unlike Earth where you have rock grinding against rock/magma)

Linguo

The tectonic plates on earth are sitting on magma whereas the crust of titan is sitting on a sea therefore it could be a build up of internal heat (although not enough to create loads of cryovolcanoes) from the sea below and chemical reactions. found this:

The material erupting from the volcano might be a methane-water ice mixture combined with other ices and hydrocarbons. Energy from an internal heat source may cause these materials to upwell and vaporize as they reach the surface. Future Titan flybys will help determine whether tidal forces can generate enough heat to drive the volcano, or whether some other energy source must be present.

RedPlanet

I actually emailed the proponent of this theory.
Ralph Lorenz (whom was a student of John Zarnecki).
Just asked him why we don't see many cryovolcanoes and major fissures, particularly since the surface is meant to move so much.
He replied straight away, and just said: If the crust is bouyant, why expect it to sink?
He also said there are cryovolcanoes.
Didn't really elaborate on how many/ how few.

And he suggested I read his book: Titan Unveiled.
http://www.amazon.co.uk/Titan-Unveiled-Saturns-Mysterious-Explored/dp/0691125872
Which, i'm probably going to get!

*i also wonder about the heat that must be generated internally, to prevent this liquid from freezing. Apparently they think there's also lots of ammonia, which could act as an anti-freeze. But if there is internal heat, it's gotta go somewhere..

Linguo

Brilliant!

How do you know him!?

RedPlanet

I don't.
I just found his website and fired off an email.
Got a reply in under an hour.
Fair play to him.

Linguo

That's cool, I have John's but think he's prob too busy to answer all our questions!

Hope he's back over soon