What makes you think the rules regarding buoancy are any different for cryogenic liquids, than they are for room temperature liquids?

The probe is designed to float, thus it has a density less than liquid methane. I heard a fascinating talk on Titan at work, apparently the probe will drift quite a while before touching down...I look forward to the pictures and data it sends back...

On a tangentially related note, LN2 is fun to play with... When I was teaching physics lab courses I came up with a funny routine to shock my students- I would take various objects (rubber tubing, rubber erasers, bananas etc) and hold them in a dewar with tongs intil they froze solid then drop them on the floor where they shattered like glass... I would 'accidentally' drop the third item into the dewar, then I'd calmly roll up my sleeve, and reach into the dewar and retrieve the item... (rolling up the sleeve is VERY important to avoid injury- as is speed) It usually would get a few students to jump and gasp... I would then explain the leidenfrost effect to them...the LN2 boils in contact with your skin, creating a vapor barrier between your skin and the liquid... you can put your arm in LN2 for a short time and grab a frozen item... the important thing is to never let the item touch your skin for any long period of time...

I did get a talking to when i pulled the following stunt: I first put on a thin rubber glove, I briefly dipped my fingers into the LN2 dewar and showed off the leidenfrost effect, I started to explain how it works.... I finished by saying "But if you leave your hand in too long it will eventually cool enough to allow the LN2 to touch it" I plunged my fingers into the ln2 and watched their eyes bulge as i held it there as i continued my lecture...when the LN2 stopped boiling I said "this is what happens if you leave your hand in too long" I slammed my hand on the table and my fingers shattered...

Several people of both sexes screamed in horror... I had stuffed the fingers with hamburger... I was told that was not an 'acceptable' prank....no punishmint, just a talking to... But on the up side the students paid attention after that.... I think I gave a total of 5 grades that were an 'F' OR 'D'- EXTREME CASES- 3 were for cheating...the other 2 were for not showing up, and I made an effort to let them make it up- they didnt show up for the make up