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Crossing the Dunes at Murray Buttes, Sites 54-, Sols 1353-, May 28 2016-
PaulH51
post Jan 18 2017, 07:44 AM
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Three new Photojournal Catalog pages have been issued that address possible mud cracks observed by Curiosity at 'Old Soaker' and 'Squid Cove'
PIA21261: Possible Mud Cracks Preserved in Martian Rock LINK
PIA21262: Mars Rover's Mastcam View of Possible Mud Cracks LINK
PIA21263: Possible Signs of Ancient Drying in Martian Rock LINK
Modest Previews Only, for full size use links above
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fredk
post Jan 18 2017, 05:12 PM
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It's been very rare to see dust devils at Gale, but I think we had one on sol 1582. Flipping between two of the navcam pairs shows a faint verticalish streak in these gif animations:
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Subtracting the corresponding frames and stretching reveals the streaks better (these cover exactly the same parts of the frames as the gifs above):
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The DD moves left to right (crudely east to west), crossing from one frame pair to the other.

It also looks like there's a much more diffuse DD/gust on the right side of this difference frame:

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Phil Stooke
post Jan 18 2017, 07:38 PM
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That is a great discovery, Fred - well done. I've been looking for DDs throughout the mission (but only sporadically). This is only the second one I know of, the first being a distant and very faint one on sol 41. Faint though these may be, they are much clearer and more convincing than the older one.

I did a bit of different processing of the same data (after seeing your post). Each image is a stretched difference image (bottom) and the stretched image superimposed on the landscape (top).

Phil

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jvandriel
post Jan 18 2017, 07:58 PM
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The Navcam L view on Sol 1582.

Jan van Driel

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Phil Stooke
post Yesterday, 01:31 AM
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Nice panorama, Jan. Here it is in circular form.

Phil

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PaulH51
post Yesterday, 01:46 AM
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Here's a rough and ready 1583 pan LINK

600 px wide preview, follow link for full size
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Phil Stooke
post Yesterday, 01:52 AM
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Back to Fred's dust devil. This is the full frame from the first of the views Fred posted, to show that other gust or whatever it is.

The two frames were processed by superimposing them, turning one into a negative (invert the grayscale) and merging the two. Anything that doesn't change becomes a mid-range gray, but anything that changes shows up white or black. That composite was stretched, despeckled a bit, and superimposed on the landscape.

Phil

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EDIT: and the other view. There is a third image pair but nothing shows up it them.

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Phil Stooke
post Yesterday, 03:23 AM
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Paul's sol 1583 pan in circular form.

Phil

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fredk
post Yesterday, 05:32 AM
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QUOTE (Phil Stooke @ Jan 19 2017, 02:52 AM) *
This is the full frame from the first of the views Fred posted, to show that other gust or whatever it is.

Nice job, Phil - I like the way you've superposed the differences onto the original frames. Your images show that the devil on the left side of the later frames seems to extend up against the sky, where it produces a darkening.

The main DD appears to be behind the mid-distance horizon line, so an estimate of that horizon's distance would allow someone to put a lower limit on the size of the DD, and, given its movement from frame to frame, a lower limit on its speed...
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Phil Stooke
post Yesterday, 02:30 PM
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Fred's discovery prompted me to look back a bit, and I found another DD or dust-raising gust of wind from sol 1570:

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There is also a very faint one in the same area from sol 1568.

Phil


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Phil Stooke
post Yesterday, 06:07 PM
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Sol 1568 - two features. This is the middle view of a set of three image pairs. The left and right image pairs each have something very faint but real - I won't post them here, they look horrible! But there were clearly 4 events in the whole sequence.

Phil

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EDIT - also 3 events on sol 1565... I'm seeing them in most of the available sequences now. I hope the project will put out its own announcement soon.


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