Titan's Equatorial Sand Seas |
Titan's Equatorial Sand Seas |
May 7 2007, 03:53 PM
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Senior Member Group: Moderator Posts: 2785 Joined: 10-November 06 From: Pasadena, CA Member No.: 1345 |
I’ve put together a sequence of events that could explain the morphology of the Equatorial Sand Seas. (An example basin similar to Shangri-La is shown)
This could explain the ria-like topography [http://en.wikipedia.org/wiki/Ria] on the Eastern shore, as well as the VIMS dark blue western parts of the Sand seas, and the placement of the dark brown unit on the Eastern parts of the sand seas. 1. Basin formation. 2. Water-ice sand deposition [slowly, suddenly?] forms an ice-sand margin 3. Mobile dark brown dune sands deposit on E side, depositing inland up W facing valleys. :attachment] The dark brown sands will blow in following the predominantly W winds and make a dust coating on low-lying terrains on the eastern margins. This will be visible by VIMS and ISS as the dark-bright margin, placed “inland” from the "real margin" and will accentuate the local topography as seen by optical instruments. This accentuation on the E margin will make the Equatorial Sand Sea visible margin look “swoopy” and windblown (in effect, it is) from the dark basin. Similarly, the W margin will have a dark blue zone that appears blown from the western bright areas. On the Eastern shore, the RADAR images will place the smooth-dark/mottled gray boundary far to the W of the VIMS brown dark-bright margin. (RADAR should be able to penetrate a thin coating of dark sands). The features in the limbo zone have been covered by dark sands, perhaps not enough to form dune structures, but enough to cover up the ice-sand margin, the near shore terrain, and perhaps even some of the underlying bright terrain. This makes the deposition sequence in the Equatorial Sand Seas: 1: Basin formation 2. Major water ice sand emplacement 3. Dune sands cover up low-lying downwind valleys (enough to mask visible imagery) Other Equatorial Sand Sea basins should look very similar around Titan: Shangri-La, Belet, Senkyo, Fensal and Quivra. Local winds may play a bonus role, but the overall trend of dark sand deposition up valley should be towards the E. For example: the false-color image in Figure 6 of the Soderblom paper seems to imply a predominant wind vector in Fensal and Quivra to the ESE. [I’m pretty sure all this has been described in pieces before, but it gave me a really great excuse to play with PowerPoint. ] -Mike -------------------- Some higher resolution images available at my photostream: http://www.flickr.com/photos/31678681@N07/
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Jun 20 2007, 09:42 PM
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#2
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
Juramike I salute your work, but sadly I doubt if there is an 'amateur' here now who can enter a critical discourse on your evidence and findings at the level they deserve. I excuse our resident professionals because of course they conduct most of their discourse in their own arena. I'd just like to register a few points, easily made armchair comments compared with what you are doing.
Philosopy My preference at the moment is to hedge my bets as far as global models for Titan are concerned. Many of my ideas about the place are mutually contradictory (you've probably noticed!) but I'm happy with that and prefer to keep it that way until we have done more plain and simple looking. I'm not comfortable in a 'house of cards', even one that seems to be holding up well at the moment. I'm on the lookout for surprises - the sort of thing that brings card houses down. I don't want to miss one because I've formed a view too early. next bit in following post |
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Jun 21 2007, 03:15 PM
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#3
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Senior Member Group: Moderator Posts: 2785 Joined: 10-November 06 From: Pasadena, CA Member No.: 1345 |
Philosopy My preference at the moment is to hedge my bets as far as global models for Titan are concerned. Many of my ideas about the place are mutually contradictory (you've probably noticed!) but I'm happy with that and prefer to keep it that way until we have done more plain and simple looking. I'm not comfortable in a 'house of cards', even one that seems to be holding up well at the moment. I'm on the lookout for surprises - the sort of thing that brings card houses down. I don't want to miss one because I've formed a view too early. I can respect your caution. My philosophy is to try to build a model that tries to fit and explain the current observations and is hopefully predictive of future observations. My personal scientific philosopy that even a bad model is better than no model. (If it's proven wrong, at least we can say "Well, it's not that!") Building a model will hopefully tell us where to look to support/disprove the model. Always bearing in mind the important rules of science: "You can never prove a theory." (You can provide evidence that supports a theory, but you can never prove it.) "Absence of evidence is not evidence of absence." "You can't zoom a zoomer." (Zoom, schwarz, profigliano, beterman rules here) I'm hoping that an initial model will also help to develop experiments in the lab as well as plan what future observations might be helpful. And scientific models are built to be modified, mangled, ripped up, parted out, and reassembled, and if need be, totally thrown out the window. [The standard scientific bet in our lab is a quarter: some days I'm lucky and the quarter is on my desk, other days when my hypotheses don't do so well, it goes to a someone with a better predictive model] And please continue to be on the lookout for suprises, those are the key observations that will help build the next (always better) model... -Mike -------------------- Some higher resolution images available at my photostream: http://www.flickr.com/photos/31678681@N07/
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Jun 21 2007, 03:36 PM
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#4
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Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
"You can't zoom a zoomer." (Zoom, schwarz, profigliano, beterman rules here) OMG! I haven't played that particular drinking game in 30 yers! (I believe, at the time I learned it, that 'Beterman' hadn't codified it yet -- it was simply known to me as "Zoom-Schwartz-Profigliano-Zoom.") I learned that game in my junior year of college (otherwise known as the Great Sodden Semester... ) I totally agree in terms of developing models, even on insufficient data, Mike. It is often the process of building a model that shows you what's not consistent with your base assumptions, and sends you out looking for data to confirm or deny certain of those base assumptions. It is perhaps possible to learn more by simply going out and collecting every scrap of data that you possibly can, but we all know that data-collection schemes (and the sensors used to collect the data) are so specialized these days that you have to triage -- you have to decide in advance what kind of data you're going to collect in any given scheme (read: any given mission). For that task, you need a model and you need a set of base assumptions that you want to test. Without that, you can end up either getting tantalizing hints of things you just didn't have the tools to investigate or, worse, you miss something extraordinary that you could have seen if you had flown the proper types of sensors. -the other Doug -------------------- “The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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