On the Road Again - volume 8 - Page 8

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Author Message
Bill Harris


Posts: 3

Reply: 141



PostPosted: May 5, 2011 9:16 AM 

The datastream has gone Looneytunes. A flood with month-or-two-old duplicates included in with current images and a dribble of last week's reticulated terrain images.

Sigh.

--Bill

Barsoomer


Posts: 344

Reply: 142



PostPosted: May 5, 2011 11:26 AM 

Agreed, Bill; I hate it when they do that. I think Horton must be correct that the images were embargoed on account of that hardly earth-shattering press release. The images are better organized at the JPL site, though.

Nice photo for Oppy's family album.

Kye Goodwin


Posts: 1166

Reply: 143



PostPosted: May 5, 2011 3:20 PM 

Horton, Re your 138, I'm interested in both the reticulated terrain and the craters. I see you have already created panoramas that illustrate the reticulated terrain more clearly than any individual image that I could find. Thanks.

Bill Harris


Posts: 3

Reply: 144



PostPosted: May 5, 2011 4:35 PM 

@Serpens: "I think Horton must be correct that the images were embargoed..."

I just flipped back and read that. Outlandish as that sounds, it does seem to fit what is happening. OMG, the project is being directed by Senior Administrative Interns. And to make matters worse, they appear to be piddling the data out 2-3 times a day.

Sigh.

--Bill

hortonheardawho


Posts: 3465

Reply: 145



PostPosted: May 5, 2011 7:48 PM 

sol 2597 ( May 5, 2011 ) next drive direction:

with pancam detail and guestimated map location.

I redid the guestimate map because I was unhappy with several problems. At first I assumed that the drive was a linear drive which ended up about 17 meters from the rim of Freedom 7 crater. But the drive index changed from B6QZ to B6Z4 for a drive of 293 units = 58 m. Also, I couldn't find any features that matched the navcam view in the next drive direction. Once I allowed that the sol 2587 position could be anywhere 17 meters from the rim I located features that matched the navcam images.

The actual drive may not have been a southward leg followed by an eastward leg.

And here are the sol 2581 images in the reticulated soil area - including 2 180 degree navcam pans and vertical pancam pans.

The cells appear to be more than just ripples. There is real subsoil structure. I'll leave it to the rock guys to speculate about their true nature.

Barsoomer


Posts: 344

Reply: 146



PostPosted: May 5, 2011 11:02 PM 

Horton, in your #145 image, foreground to the left of the sundial deck area, there is an apparent impression of a slab in the soil, but the slab itself seems to be gone. What could remove a pavement slab? From the raised soil around the "slab impression" it seems unlikely to be wind erosion. Chemical erosion?

Thanks, Horton, for the images of the reticulated area. The SE part is particularly striking. I see a honeycombed pattern that is perhaps repeated at different scales (fractal).

hortonheardawho


Posts: 3465

Reply: 147



PostPosted: May 5, 2011 11:57 PM 

Barsoomer, maybe the same mechanism that created the reticulated soil patterns created the depression in reply 145?

One word Benjamin: sublimation.

Serpens


Posts: xxx

Reply: 148



PostPosted: May 6, 2011 12:19 AM 

Hortonheardawho seems correct that the 'reticulated' area is more than just ripples, and as Barsoomer says there is widespread repetition. I will stick with a joint set as the initial cause of the features, with heavily indurated fill resisting erosion. Some material has drifted up against the raised, erosion resistant fill which probably led to Ben's identification of the features as ripples. But this is another piece of evide3nce for a wet past, and as always iot is only beiong analysed in the rear view mirror.

Barsoomer


Posts: 344

Reply: 149



PostPosted: May 6, 2011 12:12 PM 

It seems that we all believe that Meridiani was wet in the distant past when the sediments were laid down. Maybe wet and cold. In that case, there may have been lenses of ice that were incorporated in the sediments. How likely is it that some of these buried lenses of ice may have survived until more recent times, at which point they were exhumed and then sublimed away?

Kevin Author Profile Page



Posts: no

Reply: 150



PostPosted: May 6, 2011 12:25 PM 

Mars Rover Driver has Tweeted - "77% of the way to Endeavour. Slightly delayed by stop at Freedom 7, now back on the road and zooming along"

Kevin Author Profile Page



Posts: no

Reply: 151



PostPosted: May 6, 2011 12:27 PM 

And a previous tweet: Driving Opportunity for nearly four hours today. Maybe 160m or so, possibly even better, unless thermal or other concerns cut us short.

hortonheardawho


Posts: 3465

Reply: 152



PostPosted: May 6, 2011 12:32 PM 

sol 2588 ( May 6, 2011 ) in next drive direction:

with a link to a guestimated map position.

I was so pleased that my sol 2587 position was off by only 1/2 meter from the official sol 2587 traverse map position that I decided to try and guess the sol 2588 position from this single navcam image.

The essential data is that the rover is about 8 meters from a 3 meter "inverted ( raised ) soil circle" on a 158 degree heading.

I used a guestimated heading and drive time from the sol 2587 position to locate a search area for a soil circle. the general features of the area near the circle seem to match well also.

Has anyone proposed exactly what these peculiar inverted ( raised ) soil circles might be?

I think a big clue is the fact that they are associated with the reticulated soil areas.

Barsoomer


Posts: 344

Reply: 153



PostPosted: May 6, 2011 1:52 PM 

Polygons with humps in the middle? Horton, could you do a 3D stereo versions of just that area?

John


Posts: xxx

Reply: 154



PostPosted: May 6, 2011 1:57 PM 

Whee....just look at the hexagonal pattern!

John


Posts: xxx

Reply: 155



PostPosted: May 6, 2011 2:02 PM 

There are enough polygonal tundra images on google images to choke a horse.

Kye Goodwin


Posts: 1166

Reply: 156



PostPosted: May 6, 2011 3:06 PM 

Horton, re your 152, Yes, there seem to be a few circles "integrated" into the reticulated (net-like) ground pattern as seen from space. Circles are always assumed to be derived from craters unless one has a really good reason to think otherwise.

There isn't much to go on in explaining the patterned ground. I haven't seen any rock exposed in the ridges, but they appear to be harder than typical plains ripples based on the rover track:

Small SW-NE trending ripples, which I've been calling the plains cross-ripples, have formed on the ridges, and these additions have been crushed by the rover wheels. These ripples have formed on the higher parts of the surface as they have in many other places. Where the underlying ridges are close to the SW-NE orientation long cross-ripples form on the tops. Ridges with an orientation that differs a lot from SW-NE have many short cross-ripples on top instead:

The ridges ahead have the N-S orientation of the big plains ripples:

It will be interesting to see if these ripple-like ridges are also hardened, like the reticulate ridges. This should be revealed soon by the rover track.


Kye Goodwin


Posts: 1166

Reply: 157



PostPosted: May 6, 2011 3:28 PM 

How are these two craters related?:

The second one (the large smooth one upper right in the image) is only a little smaller than the first one. Is the smooth one just older than the rocky one? The wall crest (or rim crest) of the smooth crater is much crisper than the wall crest of the rougher, presumably younger, crater. What process has created that sharp crest out of a messy rim like the first crater? It seems like a simple wearing down of the breccia could never produce that crisp shape of the "older" crater no matter how long the process goes on.

Barsoomer


Posts: 344

Reply: 158



PostPosted: May 6, 2011 3:56 PM 

Hardened linear features that are a little lumpy? Fossilized frozen streams that might still contain some underground fossil ice? (Or did until this area was exhumed?)

John


Posts: xxx

Reply: 159



PostPosted: May 6, 2011 4:13 PM 

In case you have forgotten. [link]

Ben


Posts: 2270

Reply: 160



PostPosted: May 6, 2011 5:45 PM 

Barsoomer; I think you may be on to something.
We are reportedly moving down-section into older beds which could mean we have reached an old , water-table in permafost,jointed sediment. The ground water could have been frozen at this previous depth by a change in climate but subsequent erosion exposed it so that sublimation of the water allowed the sediment to collapse between the more resistant joints.
The polygons in Horts 152 may be a manifestation of permafrost as well.

The odd circular features with slight rims? which vary in size,are not restricted to the reticulated area. They have been present since we left SM and continue all the way to the Cape.
My best guess is that they represent historical,traces of old, now exhumed craters.

Kye: I think it is obvious the features you refer to in 157 are craters caused by impact .
The rocky ones are younger and are just now being modified by wind erosion whereas the smooth ones are eroded ,older features (now exhumed)that drifting sand is currently changing slightly.

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