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Titan exploration beyond Cassini
titanicrivers
post Feb 7 2017, 10:42 PM
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Beyond Cassini
Two proposed future Titan missions to be presented at the 2017 LPSC conference http://www.hou.usra.edu/meetings/lpsc2017/pdf/1958.pdf and http://www.hou.usra.edu/meetings/lpsc2017/pdf/2306.pdf
promise to extend and enhance Cassiniís discoveries concerning this marvelous world.
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PhilipTerryGraha...
post Feb 9 2017, 12:12 AM
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I presume Dragonfly is also a New Frontiers 4 entrant?


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nprev
post Feb 9 2017, 01:49 AM
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ADMIN NOTE: Moved topic to "Past and Future" "Exploration Strategy" since these are still notional missions.

EDIT: Oops!!! smile.gif


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TheAnt
post Feb 9 2017, 10:14 AM
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I really like the Dragonfly proposal, but I am afraid the chance of seeing it happen is very small indeed.
It's similar to the drones most of us are familiar with now.
Now constructing a multipropeller drone that will have to function in that temperature range and environment is both difficult and risky in several ways.
Some metals have brittle 'ductile-to-brittle-transition'. and what substance to use as lubricant in the bearings?
(Copper might be used in wiring and bearings though - if I remember correctly it's a metal that don't have the BDT transition.)
Anyway I think NASA and ESA are a bit to risk aware to seriously consider this one, and for the other agencies, it's outside their capability.
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rlorenz
post Feb 11 2017, 03:49 PM
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QUOTE (TheAnt @ Feb 9 2017, 05:14 AM) *
I really like the Dragonfly proposal,......


I'm glad you like it, it has been a lot of fun to work on.

I'm not going to get into a to-and-fro on a competitive proposal, but your metallurgy risk comment is not well-founded. Engineering systems operate in Titan-like
conditions all the time in the liquefied natural gas industry (and in launch vehicles with cryogenic propellants like liquid oxygen) The relevant materials are well-understood - Huygens didn't smash into pieces.

As for rotors, they don't need gearboxes so the lubrication is a much simpler problem than for rovers, for example.

Of course, all these and other technical challenges will receive close scrutiny during the review process, which I am not going to prejudice with further discussion in this forum.

Over the years I have formulated an aphorism of planetary vehicle design :
"It is possible to contrive a pathological planetary scenario that will defeat any finite-cost space system".
So reductio ad absurdam, to avoid risk altogether, you stay at home. I hope that is not NASA's posture.
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vjkane
post Feb 12 2017, 06:02 AM
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I too like the Dragonfly concept. It's a clever approach that combines the best of aerial surveys (remember all the proposals for Titan balloons), landed science, and mobility.

I would guess that the key issue is showing that it can fly autonomously and find a safe landing site at the end of each flight. Does anyone know whether there are systems in use on the Earth to do similar autonomous flying and landing? One approach might be to limit the prime mission to areas with less challenging terrain.


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Explorer1
post Feb 12 2017, 06:21 AM
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How would we know what the least challenging terrain is, though? We're still at pre-HiRise levels of high resolution coverage for Titan. Viking 1, 2 and Pathfinder landed at what seemed to be 'smooth' areas from orbit but surface images revealed plenty of sharp rocks. Though who knows how good autonomous navigation software might be by the time anything is actually ready for launch...
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nprev
post Feb 12 2017, 10:22 AM
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Safe landing spot...hmm. You'd need a pretty short-wavelength radar to find such a place that way, and the instrument would likely be power & mass prohibitive (unless you could also justify good science return from it somehow, which seems unlikely).

Sounds like you gotta use the imaging system; maybe have it start looking 30 min before 'bingo' touchdown time using stereo pairs to find a clear spot of minimum specific dimensions. Might be able to constrain slope as well that way, but that seems a bit difficult. Also, if it's flying in an area likely to have surface liquids it either has to be buoyant and survivable in that environment or be able to discriminate between a liquid & solid surface, which again seems challenging using even fairly advanced real-time AI imagery analysis.


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HSchirmer
post Feb 12 2017, 06:17 PM
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QUOTE (nprev @ Feb 12 2017, 11:22 AM) *
Sounds like you gotta use the imaging system; maybe have it start looking 30 min before 'bingo' touchdown time using stereo pairs to find a clear spot of minimum specific dimensions.
...
seems challenging using even fairly advanced real-time AI imagery analysis.


Ya might be surprised at what real time imagery can do.
QUOTE
http://foxtrotalpha.jalopnik.com/how-dumb-...mart-1673486769
As these hockey puck-like Skeets fly through the air while rapidly spinning, a small infrared imager and laser ranging system activates on each one. The infrared seeker rapidly scans the ground below for an enemy vehicle or weapons fixture that it can recognize, while the laser ranger provides a ground contour map.
...
Ok, so I know you reading this and asking yourself: "are you telling me these little flying pucks can recognize bad guys' vehicles and automatically decide whether or not to engage them while they spin freely through the air at high RPM?" The answer is unequivocally YES.


See
https://i.kinja-img.com/gawker-media/image/...52v0esguj9i.gif





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vjkane
post Feb 13 2017, 12:09 AM
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I expect that parts of the solution to the safe landing of the Dragonfly might be overlapping imaging (phodar) and/or lidar. I'm certain that all the pieces are there; I'm wondering if they've been put together in a complete package tested in use. If they have been, the military would seem likely the likely developer and user.

Since this is an obvious question, I'm sure that the proposers have an answer. I'll be interested to see if they choose to share it.


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nprev
post Feb 13 2017, 12:56 AM
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Yeah, I'm very curious as well. The elegant method would be to dual-purpose one or more science instruments here, but OTOH that might add complexity and increase risk in other ways (esp. software). It'll be interesting to see how it's to be done.


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TheAnt
post Feb 13 2017, 06:44 PM
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QUOTE (rlorenz @ Feb 11 2017, 04:49 PM) *
I'm glad you like it, it has been a lot of fun to work on.

I'm not going to get into a to-and-fro on a competitive proposal, but your metallurgy risk comment is not well-founded. Engineering systems operate in Titan-like
conditions all the time in the liquefied natural gas industry (and in launch vehicles with cryogenic propellants like liquid oxygen) The relevant materials are well-understood - Huygens didn't smash into pieces.


Thank you for the reply, Rlorenz.
No I never expected Huygens to shatter on impact - hehe. And a good aphorism there also. smile.gif
But I did wonder if fast moving propellers and their vibrations might be at risk in one way of other, all happy to be told my fears were wrong.

The following posts seem to have addressed the other problem I had in the back of my head - the need to land at a safe place for the RTG to charge up the batteries for next flight.
For whatever it's worth the Dragonfly get my thumbs up - for whatever it's worth. Quite more data and information can be gathered from a moving platform.
So let's hold thumbs that the idea might get a serious consideration. =)
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