Author Topic: Mars Dune Seperation Measurement Needed  (Read 1481 times)

Offline Apollo-phill

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Mars Dune Seperation Measurement Needed
« on: 09/11/2010 08:41 PM »
Hi

Does anyone know what the approximate distance (in metric or imperial units) is from one 'sand dune top' to another 'sand dune top' in the dunes being seen in images taken by MER Opportunity on its travels to Endeavour crater ?

Also, roughly, the height of these small dunes ?

If there is a 'wild' variation in the above figures, if possible, could you please quote the lowest and highest heights and the smallest/largest distance please.

If possible - would prefer details before end 17th September 2010.

Any help appreciated.

Thanks


Phill
UK



Offline Sparky

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Re: Mars Dune Seperation Measurement Needed
« Reply #1 on: 09/11/2010 09:01 PM »
Have you tried counting the number of "cleat" marks in the tracks behind opportunity to get a better sense of scale?

Offline hop

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Re: Mars Dune Seperation Measurement Needed
« Reply #2 on: 09/11/2010 09:23 PM »
Does anyone know what the approximate distance (in metric or imperial units) is from one 'sand dune top' to another 'sand dune top' in the dunes being seen in images taken by MER Opportunity on its travels to Endeavour crater ?
You should be able to get the horizontal characteristics quite accurately from HiRISE images. Some of them even have rover for scale.

The size of the ripples does vary dramatically, so there won't be a single number.

You will find the unmannedspaceflight.com forum http://www.unmannedspaceflight.com/index.php?showforum=2 a great resource for all things MER.

Offline npuentes

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Re: Mars Dune Seperation Measurement Needed
« Reply #3 on: 09/16/2010 12:24 PM »

[/quote]
You should be able to get the horizontal characteristics quite accurately from HiRISE images. Some of them even have rover for scale.
[/quote]

You don't even need the rover. Download the map-projected HiRISE images from http://hirise.lpl.arizona.edu/. The pixel scale for most data is 25 cm, with a few at 50 cm and far fewer (in dark areas) at 1 m. These images are not orthorectified, so beware of slopes (for that you need a digital elevation model,which are also provided for some image), but you can get very close to the ripple spacing by just counting pixels between crests.

Offline iamlucky13

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Re: Mars Dune Seperation Measurement Needed
« Reply #4 on: 09/17/2010 01:57 AM »
If you need to be accurate, you can get raw or minimally processed MRO images off the Planetary Data System, plus orbital information that will allow you to accurately determine scale.

Really though, that's effectively academic-level study. For any casual interest, I'd just go with npuentes suggestion to use images from the HiRise public site. Some of them state the image scale in the caption.

My impression of the scale from the MER images is dune separations of 10-20 meters and dune heights of 1/4 to 1 meter.

You wouldn't want to quote me on that, though.

Offline npuentes

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Re: Mars Dune Seperation Measurement Needed
« Reply #5 on: 09/17/2010 11:17 AM »

Really though, that's effectively academic-level study. For any casual interest, I'd just go with npuentes suggestion to use images from the HiRise public site. Some of them state the image scale in the caption.


You wouldn't want to quote me on that, though.

Actually, the processed images are better than raw, as they are map projected, so take out large scale distortions due to viewing geometry. Anyway, all of this is probably more information than "iamlucky13" needs. Good luck.

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