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Proposed Titan Paddle Boat Mission, The Titan Lake In-situ Sampling Propelled Explorer (TALISE) proposes a
Phil Naranjo
post Sep 27 2012, 07:24 PM
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I saw this article today: The Titan Lake In-situ Sampling Propelled Explorer (TALISE) proposes a sending an instrument-laden boat-probe to Saturnís largest moon.

Read more: http://www.universetoday.com/97611/paddleb.../#ixzz27hR16wOH

I was under the impression that the liquid hydrocarbon lakes of Titan were highly viscous, more tar like? Prior to Cassini, I recall speculation by scientists that Titan might harbor giant waves.

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djellison
post Sep 27 2012, 07:48 PM
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Everything I've read suggests the lakes are ethane/menthane - not longer more tar like hydrocarbons.

Some of the SAR Topo passes have shown the surfaces to be mill-pond smooth.
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ngunn
post Sep 27 2012, 08:53 PM
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The idea is just too good to give up on. C'mon everybody: TITAN BOAT, TITAN BOAT, TITAN BOAT . . .
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djellison
post Sep 27 2012, 09:16 PM
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Seems like a lot of mass/complexity to do something that the winds are going to do to you anyway, right? I wish we had the budget to do TiME, CHopper and InSight.
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ngunn
post Sep 27 2012, 09:23 PM
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QUOTE (djellison @ Sep 27 2012, 10:16 PM) *
Seems like a lot of mass/complexity to do something that the winds are going to do to you anyway, right?


Exactly my thought: mass, complexity and, not least, energy for a very inefficient propulsion system. But hey - let's keep the idea flying. NASA is not the world.
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Eyesonmars
post Sep 27 2012, 09:31 PM
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The lakes of Titan cover only what ,1-2% of the surface? And being seasonal and the result of precipitation they can't be much else besides pure ethane or methane. So sampling these liquids wouldn't tell us much.
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ngunn
post Sep 27 2012, 10:04 PM
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Earth's oceans are mostly water, but their minor constituents tell just about the whole story of what's going on on this planet now. Trace chemicals from geology and weather mainly, but there's agricultural chemicals, false eyelashes, plastic wrappers and pharmaceuticals in there too. Everything accumulates in bodies of liquid. It's reasonable to suppose that this also applies on Titan, given its weather system's ability to move stuff about.

EDIT: The large northern lakes are not seasonal if you mean by that they disappear once a year. There's too much liquid there. They may disappear and re-form over the longer timescales proposed by Aharonson (Croll-Milankovich cycles) but in my view that would not greatly diminish their value as science targets.
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stevesliva
post Sep 28 2012, 02:18 AM
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QUOTE (ngunn @ Sep 27 2012, 05:23 PM) *
Exactly my thought: mass, complexity and, not least, energy for a very inefficient propulsion system. But hey - let's keep the idea flying. NASA is not the world.


Oh, I'm sure some mechanical engineer would love to figure out how to make an ASRG run a paddlewheel as well as an alternator.
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Fran Ontanaya
post Sep 28 2012, 03:10 AM
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I think I read liquid methane would be half as viscous as water. Also I think the big waves theory was abandoned too. Forgive my bad memory if I'm wrong.

I'm curious about heat isolation, I wonder how much leakage would make the boat float on a pad of vaporized methane.


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mcaplinger
post Sep 28 2012, 04:20 AM
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QUOTE (Eyesonmars @ Sep 27 2012, 02:31 PM) *
And being seasonal and the result of precipitation they can't be much else besides pure ethane or methane.

I guess you haven't heard of the carbon cycle on Titan. See http://www.kiss.caltech.edu/workshops/tita...s/aharonson.pdf for starters. The science goals of a Titan lake mission were rather well studied by the TiME Phase A study, alas not selected. See http://en.wikipedia.org/wiki/Titan_Mare_Explorer


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rlorenz
post Sep 28 2012, 07:57 AM
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QUOTE (Phil Naranjo @ Sep 27 2012, 03:24 PM) *
I saw this article today: The Titan Lake In-situ Sampling Propelled Explorer (TALISE) ......

I was under the impression that the liquid hydrocarbon lakes of Titan were highly viscous, more tar like? Prior to Cassini, I recall speculation by scientists that Titan might harbor giant waves.


I saw their poster at EPSC yesterday. I'll restrain myself from critical comment but the paddle-wheel thing is rather cute, and in principle is a viable solution to locomotion in a tar-like environment.

ngunn summarizes the situation well : the situation is complex in that there is likely no single description applies to all bodies of liquid on Titan. The Croll-Milankovich cycle in the present epoch favors accumulation of methane/ethane in the north (which is where we see the large seas like Ligeia), so we may expect them to be rather fluid - hence sailing works fine there and you don't need paddles.

The south is drying out, consistent with paucity of liquid bodies seen in that hemisphere, and the rather shallow and possibly shrinking depth of the largest (but still somewhat small) lake, Ontario Lacus. We might expect Ontario to be more viscous than the northern seas and lakes, so a paddle-steamer might make more sense there than in the north. Which is just as well, since the seasonal geometry makes direct-to-earth communication progressively more difficult into the late 2020s from the northern polar regions, so for a 2030+ arrival timeframe Ontario makes more sense as a target.



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Eyesonmars
post Sep 28 2012, 01:00 PM
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QUOTE (mcaplinger @ Sep 28 2012, 04:20 AM) *
I guess you haven't heard of the carbon cycle on Titan. See http://www.kiss.caltech.edu/workshops/tita...s/aharonson.pdf for starters. The science goals of a Titan lake mission were rather well studied by the TiME Phase A study, alas not selected. See http://en.wikipedia.org/wiki/Titan_Mare_Explorer

Thanks. I'm not aware of the supposed carbon cycle on Titan. I should have done some additional reading before making my comments. Apologies to all.

I don't make a living in these fields like the rest of you. But my observation as an interested and (relatively) informed but average Joe taxpayer is :
Why limit ourselves to a boat when we could have an aerial vehicle that could potentially sample the entire planet. I even remember reading somewhere that a balloon based vehicle could be designed such that multiple trips to the surface are possible, even liquid landings. ( complexity i guess)
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nprev
post Sep 28 2012, 03:08 PM
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QUOTE (Eyesonmars @ Sep 28 2012, 05:00 AM) *
I should have done some additional reading before making my comments. Apologies to all.


<Mod hat on> Apology accepted, and please also try to keep your comments on-topic for a given thread. Many alternative methods of exploring Titan have been extensively discussed in other threads on the Forum; I enourage you to explore a bit. smile.gif



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Juramike
post Sep 28 2012, 03:31 PM
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The idea of a self-propelled lake probe transecting across a Titan lake is pretty cool (!). The ability to selectively target the shoreline, or a bay or river inlet would provide the bonus of learning about the materials and composition of runoff or seeps. (Might even get lucky and sample during a storm-runoff event.)


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JRehling
post Sep 28 2012, 05:16 PM
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QUOTE (Eyesonmars @ Sep 28 2012, 06:00 AM) *
Why limit ourselves to a boat when we could have an aerial vehicle that could potentially sample the entire planet.


Titan is unusually diverse as worlds go, and even a highly mobile mission would have trouble sampling half the major terrain types. One hitch is that the terrain types are considerably segregated by latitude and the cheap mobility of floating in the winds will move parallel to certain terrain type boundaries and thus not cross them, at least in a timely fashion.

A second hitch is that a lot of science depends upon touching the surface, so an aerial mission either has to do semi-remote sensing (km high, with still-considerable atmospheric interference; solar illumination has still been filtered by all the haze on the way down) or have some pretty complex moving parts to enable multiple descent/ascent stages. It's a tough cost/science trade off.

Some certainties are: No one mission is going to study all of Titan's interesting terrains in situ. There is no appetite for an immediate flagship-cost mission, so naturally we're seeing proposals for good missions at lower costs. Titan merits at least as about as many dedicated missions as Mars has received, but given the vastly greater distance, it looks like this is going to unfold on a timeline that's painfully slow. People are proposing missions that might return data while they are still alive.
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