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Proposed Titan Paddle Boat Mission, The Titan Lake In-situ Sampling Propelled Explorer (TALISE) proposes a
vjkane
post Sep 29 2012, 05:22 AM
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I'll echo John Rehling's comments on Titan as a world deserving of many missions. In terms of landing, flying, or floating, it's also the easiest world to explore. On the down sides, it's distance means long flight times, plutonium power sources, and higher power communications systems, all of which means more dollars.

The ease of landing probably makes Titan cheaper to explore via a series of landers, flyers, floaters than with an orbiter (the opposite of Mars). A mission to map Titan in high resolution requires a high power communications system and a high capacity plutonium-based power system to match. Estimates come in at $1.5B up to many B's. A minimal lander mission would cost between $425M (TiME proposal team's assumed estimate) and somewhat greater than $1B (Decadal Survey estimate) for a lake lander, which represents one of the simpler missions. The AVIATR airplane mission (without a relay orbiter) was estimated to cost ~$750M. A simple relay orbiter (like that which is planned for the TALISE lake lander that started this thread) could be fairly cheap compared to a high capability orbiter, but I haven't seen estimates.

Net of all this, for much less than is proposed for NASA's Mars program, we could have a series of missions to Titan (although to be fair, the Titan craft would be less capable than the missions envisioned for Mars -- distance from Earth and the sun extracts its penalty).

TiME would have been a great mission to start a series of Titan missions. Let's hope the the TALISE proposers or another team finds the bucket of money to fly.





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TheAnt
post Sep 29 2012, 05:30 PM
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QUOTE (Fran Ontanaya @ Sep 28 2012, 05:10 AM) *
I'm curious about heat isolation, I wonder how much leakage would make the boat float on a pad of vaporized methane.


That is what I started to think when they mentioned a hovercraft design. That a more or less constant heat leakage would be utilized to collect the methane and contain it under a skirt. So far I can say there's no immediate showstoppers to that idea.
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rlorenz
post Sep 30 2012, 12:45 AM
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QUOTE (TheAnt @ Sep 29 2012, 01:30 PM) *
So far I can say there's no immediate showstoppers to that idea.


apart from it just not working quantitatively, you mean? Leaving aside the question of how much methane is in the liquid (the present models have it as only a minor constituent in the seas) I expect the condensation flux would be really high - you are essentially having to feed in power to keep the vapor out of equilibrium with the liquid. A good analogy is to watch how liquid nitrogen skitters across the floor when spilled on a lino floor - it does the air-cushion/leidenfrost thing, but the drops boil away in seconds. Hovercraft is just the same thing upside down. It would be a fun physics problem to actually calculate the flux needed on Titan (or Earth with water, for that matter) to support a given mass and/or area of vehicle, but I'd bet it turns out not to be practical.
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TheAnt
post Sep 30 2012, 02:23 PM
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@rlorenz

Yes I said that with a bit of a reservation.

Since a mission like this would be a first in many ways, and one not the least important that it would be for traveling over a surface / liquid we do not know much about - or hardly anything! So the amount of methane / ethane might indeed be one such showstopper.

Here on Earth we use hovercrafts where conditions vary, and on Titan tholin foam could be problematic.

So I did favour the hovercraft by mentioning since it would overcome the problem that paddles or one propeller working in liquid might have. Being able to travel over various surfaces. Subsurface hydrocarbon could pose a threat by grounding the vehicle. Imagine the camera on this craft on Titan only seeing a perfectly clear surface but might risk getting stuck on such subsurface ice.
And again in favour of the hovercraft, it could potentially continue past the lake and study other locations and materials on one extended mission.

Oh yes I have experimented with liquid nitrogen also, one of us thought it might risk damaging the floor, but for the very reason you pointed out, it crates a cushion of gas so it do not actually touch the floor.

Bottom line is that it might not be practical, even with the low surface gravity.
But I do think that one having one active secondary propeller or turbine to crate lift complicate any design and a risk of a breakdown.
And not the least important, the power requirement for one such would make it unfeasible from the start.

So no I did not envision anything like this one for a Titan mission. smile.gif

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atomoid
post Dec 13 2012, 02:12 AM
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i imagine if a Titan Balloon inflation payload (if not the gondola itself, or why not both!?) could be structured to drop on its own parachute to float Huygens-style on one of the lakes, we'd get the best of both worlds..
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vjkane
post Dec 14 2012, 04:53 PM
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QUOTE (atomoid @ Dec 12 2012, 06:12 PM) *
i imagine if a Titan Balloon inflation payload (if not the gondola itself, or why not both!?) could be structured to drop on its own parachute to float Huygens-style on one of the lakes,

The instrument suite proposed for the gondola is very different than the one proposed for the lake lander. The former focuses on remote sensing of the surface and sub-surface while the lake lander focuses on atmosphere/lake composition and lake properties.


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rlorenz
post Dec 15 2012, 02:26 PM
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QUOTE (atomoid @ Dec 12 2012, 09:12 PM) *
i imagine if a Titan Balloon inflation payload (if not the gondola itself, or why not both!?) could be structured to drop on its own parachute to float Huygens-style on one of the lakes, we'd get the best of both worlds..


I have in fact (on a TV shoot for '95 Worlds and Counting') been on a hot air balloon that ditched briefly in Mono Lake since we were starting to drift away from shore and recovery on the other side would take too much time. Seeing water welling up around my feet in the wicker basket was interesting. We took off again briefly by a few feet and landed on a boat which could push us back to shore to resume filming.

Anyway, point being you can land a balloon rather safely on the surface of a lake, without carrying a parachute. Whether that is the best thing to do with a balloon is of course open to debate.
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