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A question I couldn't answer
james_nicoll
Life support aside, how hard would it be to canoe on Titan?

Also posted at Dreamwidth, where there are comment count unavailable comment(s); comment here or there.

A mix of liquid ethane and liquid methane would have a specific gravity of around 0.5, half water. So you need a larger canoe.

You'd need a canoe made from materials robust at what, 90 K? Plus a good enough insulator that you weren't surrounded by hydrocarbon vapour. (A canoe hull surrounded by boiling gas and not in contact with the liquid it's trying to float in won't be very stable.)

And whatever you do, don't dump the canoe; immersing your suit radiator has to be a very bad thing to do.

Will the lower viscosity of methane be noticeable? I mean, you'd notice if the viscosity was higher, if it was molasses say, so intuitively it seems like the opposite should also be noticeable.

It probably won't; the viscosity of water is already small enough to be almost negligible to a first approximation.

http://authors.library.caltech.edu/18615/

think Titan's lakes are going to be a lot more viscous than pure methane or ethane due to dissolved carbon and particulates.

I have no idea how to calculate viscosity for that complex fluid at 90 K and ~150 kPascals, and the paper's back of a paywall, so...

Water viscosity varies quite a bit between 0 C and 40 C, something like a factor of two. Don't recall canoes being tippier on warm days, so low viscosity might be an advantage? At least if it's really not a factor in how likely you are to put your suit radiator under.

The ratio of the viscosity of water at 0C vs. 40C is even larger than that (2.74). And the 0C-100C ratio is even larger (6.35).

http://www.nist.gov/data/PDFfiles/jpcrd121.pdf

I think about this whenever I'm boiling water to cook pasta, or watching a "throw boiling water into cold air to make snow" video.

Won't this have an effect on the Reynolds Number? And the length of the canoe.

Viscosity

(Anonymous)

2014-02-11 09:04 am (UTC)

The viscosity of Titan's lakes is still very much an open question. Pure liquid methane has very low viscosity, but (1) apparently a modest level of solutes can change that dramatically, and (2) the lack of detectable waves on the lakes has led a lot of people to contemplate a high-viscosity model.

Cassini has given us so much that we really have to pause sometimes and contemplate its limitations. It's a smallish probe that's trying to peer through a dense, murky atmosphere using a series of flybys. It's amazing we know as much as we do, but a lot of big questions are still open.


Doug M.

The 0.14g is going to have an effect as well, one imagines.

Right, but it has equal effect on both you and the liquid the canoe is in, so it doesn't affect the canoe size. Does affect wave size, though; it's easier to make big waves, which probably means things will feel a lot less stable.

So a very large canoe with outriggers is indicated. I haven't looked at what materials are common for canoe manufacture lately, but given the parameters of good thermal insulation and physically stable at 90 Kelvin I'm guessing both aluminum and birch bark are right out.

Waves

(Anonymous)

2014-02-11 06:46 am (UTC)

are still an open question, but so far it appears that most of Titan's lakes are rather serene most of the time. Cassini's radar has detected no waves (there's one paper that suggests that maybe it has, but so far it's a single observation).

Modeling suggests the existence of a tidal race in the narrow straits of Kraken Mare, but this has yet to be confirmed observationally.


Doug M.

Conveniently, I would think you don't need to worry about the insulation of the outrigger, as long as the beam connecting the outrigger to the inhabited part of the canoe conducts heat poorly.

Mission of Low Gravity.

At least the canoes won't collapse from excessive pressure.

A canoe hull surrounded by boiling gas and not in contact with the liquid it's trying to float in won't be very stable

But really low-drag, so a clear win for Henley-on-Titan!

I have to believe somewhere some bored chem student has experimented with skimming toy boats across liquid N2.

Timestamp says almost two hours. Now I'm imaging him frantically typing away at a computer until he found the image he was looking for.

Nah. Emailed my brother, who knew exactly where to find the image.

If you put life support aside, you'll be dead, so I imagine it'd be pretty difficult. (rimshot, run away!)

Unless you're the Flying Dutchman.