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"Dragonfly" Titan explorer drone, NASA funds Johns Hopkins University Applied Physics Laboratory (APL)
Jaro_in_Montreal
post Dec 20 2017, 09:04 PM
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Is there a specific website for this Johns Hopkins University Applied Physics Laboratory (APL) concept for a Titan explorer drone?
Looks to be an RTG powered machine, somewhat reminiscent of MSL Curiosity (RTG sticking out the tail end).
But no camera mast, ChemCam, or sampling arm visible in the concept illustration.

QUOTE
Dec. 20, 2017
RELEASE 17-101
NASA Invests in Concept Development for Missions to Comet, Saturn Moon Titan
Dragonfly
Dragonfly is a drone-like rotorcraft that would explore the prebiotic chemistry and habitability of dozens of sites on Saturn’s moon Titan, an ocean world in our solar system.
Elizabeth Turtle from the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, is the lead investigator, with APL providing project management.


https://www.nasa.gov/press-release/nasa-inv...turn-moon-titan

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elakdawalla
post Dec 20 2017, 09:33 PM
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dragonfly.jhuapl.edu


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rlorenz
post Dec 22 2017, 01:22 AM
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QUOTE (elakdawalla @ Dec 20 2017, 04:33 PM) *


Note especially the quite detailed article that went online there this morning.(jump/scroll to resources)
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Julius
post Dec 22 2017, 03:55 PM
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This mission should easily top the list. Titan here we come! cool.gif
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Y Bar Ranch
post Dec 29 2017, 10:45 PM
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I use Titan as a case study for an aero class I teach, and am super-psyched at the idea of such a probe. Low gravity and high density are a rotorcraft's best friends.

Already drooling over the detailed 3D photogrammetry extracted from aerial images.
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vjkane
post Dec 30 2017, 05:39 AM
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QUOTE (Julius @ Dec 22 2017, 07:55 AM) *
This mission should easily top the list. Titan here we come! cool.gif

The science for a comet sample return is very compelling (as is the science for Dragonfly; it comes down to do you prefer a great apple or a great banana?).

And I'd never bet on an easy competition with any proposal lead by Squyres, and he's devoted much of his time the last three years putting his comet sample return proposal together.


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Julius
post Dec 30 2017, 12:23 PM
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QUOTE (vjkane @ Dec 30 2017, 06:39 AM) *
The science for a comet sample return is very compelling (as is the science for Dragonfly; it comes down to do you prefer a great apple or a great banana?).

And I'd never bet on an easy competition with any proposal lead by Squyres, and he's devoted much of his time the last three years putting his comet sample return proposal together.
. No disrespect to Squyres, but I can already imagine drone flying over titan lakes and magic Island plus extra miles of vistas to image and investigate. This is too good to let go and yes to me is definitely more compelling than the comet sampling mission.
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mcaplinger
post Dec 30 2017, 04:52 PM
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I share everyone's excitement, but we are unlikely to get a lot more public information about either of these missions before the downselect, and the decision isn't made based on popularity. You can go back historically and look at which missions were competing and which were selected, but even if there are clear patterns there, that's not a great indication of future decisions.


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Jaro_in_Montreal
post Dec 30 2017, 05:30 PM
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QUOTE (Julius @ Dec 30 2017, 12:23 PM) *
I can already imagine drone flying over titan lakes and magic Island plus extra miles of vistas to image and investigate.


From the description of Dragonfly in http://dragonfly.jhuapl.edu/docs/DragonflyTechDigestAPL.pdf it would not be able to go anywhere near the polar lakes region, landing instead in the equatorial dune fields.

QUOTE
Although the exploration of Titan’s seas had previously been considered, notably by the APL-led Titan Mare Explorer (TiME) Discovery concept, the timing mandated by the announcement of opportunity precluded such a mission.
Specifically, with launch specified prior to the end of 2025, Titan arrival would be in the mid-2030s, during northern winter.
This means the seas, near Titan’s north pole, are in darkness and direct-to-Earth (DTE) communication is impossible.


Like TIME, Dragonfly also proposes direct-to-Earth (DTE) communication.

Maybe a south-polar visit might be feasible ? ....Ontario Lacus ??

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mcaplinger
post Dec 30 2017, 06:03 PM
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QUOTE (Jaro_in_Montreal @ Dec 30 2017, 09:30 AM) *
Maybe a south-polar visit might be feasible ? ....Ontario Lacus ??

From the article:
QUOTE
Arrival at Titan in the mid-2030s with DTE communication suggests a low-latitude landing site. This
requirement means a similar location and season to the Huygens descent in 2005, so the wind profile and
turbulence characteristics measured by the Huygens probe are directly relevant. Furthermore, the sand
seas that girdle Titan’s equator are both scientifically attractive and favorable in terms of terrain characteristics for landing safety—indeed, it was for these reasons that the 2007 Flagship Study identified these dune fields as the preferred initial target landing area.


And it's unlikely that the vehicle will have enough range to fly from equator to pole.


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vjkane
post Dec 31 2017, 02:12 AM
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QUOTE (mcaplinger @ Dec 30 2017, 10:03 AM) *
And it's unlikely that the vehicle will have enough range to fly from equator to pole.

I'm not so sure. Assume that Dragonfly lands exactly at the equator. The north pole (and the lake region begins before this) is 4044 km away. Assume that Dragonfly has had a great prime mission and the team is willing to just push it to go the distance. At 40 km per hop once every Titan day (~16 Earth days), the north pole is 4.4 years away.

Given that Titan is pretty benign, once you've solved the problem of how to stay warm (always take your warm MMRTG with you when you visit), the limiting factor on the mission may well be how long the the MMRTG power lasts given radioactive decay.

This map in this conference abstract suggests targets that might be in the range of a primary or a first extended mission.

LPSC 2017 abstract



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Explorer1
post Dec 31 2017, 02:55 AM
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Opportunity certainly went beyond its designed range, I wouldn't be surprised that a flying vehicle could go so much farther.
I would be more worried that perhaps the environment isn't so benign; Oppy dealt with dust storms, but what about possible flash floods (as the Huygens landing site showed)? Without weather observations from orbit, that would be a nasty surprise outside the equatorial dune seas! Or the rotors' reaction to giant raindrops in-flight....
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nprev
post Dec 31 2017, 09:31 AM
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I wonder how effectively it could navigate over long distances. We don't have nearly good enough surface maps for AI terrain recognition, there's no significant magnetic field, so all that's left is inertial. Maintaining a good heading alignment over long periods may be problematic since IMUs do have inherent drift, and though periodic realignment is the usual method to correct that Titan's outer shell rotation seems to vary significantly in comparison to the rest of the moon's mass (not sure if that's a fixed offset or variable), and measuring rate & direction of rotation after vertical alignment is the usual method of finding true north (and latitude).

This could possibly be augmented by RDFing the vehicle's downlink to Earth, but not sure how much position precision could be achieved...tens/hundreds of km? Then again, maybe the position of the Sun could be used as well, foggy though it's gonna be. Dunno if Saturn would be detectable, but the Sun's definitely gonna be the only possible reference star.


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HSchirmer
post Dec 31 2017, 02:36 PM
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QUOTE (nprev @ Dec 31 2017, 09:31 AM) *
We don't have nearly good enough surface maps for AI terrain recognition, there's no significant magnetic field, so all that's left is inertial.


Not necessarily, just old-school triangulation: "1800s mountain peak GPS", using trigonometry to track where the mountain peaks are on the horizon.

Ala "the Englishman who went up a hill, but came down a mountain" you build up a triangular grid of the highest points by surveying.
That lets you triangulate your map location, and calculate your height, based where they are on the horizon.
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RoverDriver
post Dec 31 2017, 04:25 PM
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QUOTE (nprev @ Dec 31 2017, 01:31 AM) *
...
but the Sun's definitely gonna be the only possible reference star.


The nadir vector can be detected by the accelerometers. The Mars rovers we use: clock, Sun position, and nadir vector. As an alternative gyro compassing might be quite more difficult but not impossible.

Paolo


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