On the Road Again - volume 8 - Page 6

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Barsoomer


Posts: 344

Reply: 101



PostPosted: April 27, 2011 3:56 PM 

OT, but readers might find it interesting.

[link]

link

Humans to Mars: two views.

Kye Goodwin


Posts: 1166

Reply: 102



PostPosted: April 27, 2011 6:14 PM 

Horton has posted a 3D pair from this Hazcam image and it's mate, captured a few drives back (Thanks):

Most of the projecting rocks in that image are pretty clearly part of the pattern of fractured bedrock, that is, they are close to occupying the positions they held before erosion of this surface began. Why do they project above the general surface? They could project because they have not eroded as easily as the surrounding rock OR they could project because they have been lifted up out of the general surface.

I think that the projecting rocks have been lifted up. These blocks often have a flat surface that would fit nicely back into the general surface, which would not necessarily be the case if they were shaped by slower erosion. Also, we would expect that all the rock in this small area of bright plains surface would be very similar in resistance to erosion.

I'm not basing my opinion on this one example. I've been collecting examples and I'll get around to assembling something in my Natural History thread eventually. Apparently some process at Meridiani lifts blocks of rock.

hortonheardawho


Posts: 3465

Reply: 103



PostPosted: April 27, 2011 6:16 PM 

sol 2560 ( Apr 7, 2011 ) outcrop detail:

with lots of links all the way back to a 360 degree L1 27x1 panorama.

The sol 2553 ( Mar 31, 2011 ) infrared / visible saturated false color 3D images are here.

Not all the data for the four images is yet downlinked - so check later for the other two.

Yesterday's drive ( sol 2579 ) appears to have been quite long. The drive index changed from B500 to B5QX after a 4+ hour drive. My best guess for the distance is between 140-177 meters. No images, other than a few thumbnails of the drive, are available as of now.

Kye Goodwin


Posts: 1166

Reply: 104



PostPosted: April 27, 2011 11:01 PM 

Ben, re your 97 and my 95, Here's a couple of small impact craters in the bright rock:

I don't see why these craters would ever become neatly circular, no matter how long they erode. A lot of small craters would not be very circular to start with and there is no reason I can think of why they would get more circular as they disappear. Wouldn't they go from rough to lumpy to vaguely defined without ever looking like sharp little circles?

It's not that I have any idea how these tidy little craters have formed, but I suspect that there is more than relative age involved in creating the wide variety of craters that we've seen.

hortonheardawho


Posts: 3465

Reply: 105



PostPosted: April 28, 2011 8:42 AM 

sol 2579 ( Apr 27, 2011 ) L2 3x1 in next drive direction:

with a location link.

From the sol 2579 traverse map the stated drive distance was 152.9 meters!
The 10 and 30 meter craters ahead are now about 250 meters distant.

hortonheardawho


Posts: 3465

Reply: 106



PostPosted: April 28, 2011 12:24 PM 

rlewis and others:

Thought you might enjoy this sol 2556-2579 animation of the 30 and 10 meter craters ahead:

Oppy should be there by next weekend.

Ben


Posts: 2270

Reply: 107



PostPosted: April 28, 2011 1:08 PM 

Kye; Where is crater in first image located?
It could be a secondary feature and some of the debris could be impact material which tends to modify the appearance.

The ejecta in the second image is most likely affected by shock so that it would erode faster than normal and leave the circles I mention for older craters.

The dust dimples look like what a small fast moving ,falling, object would create in thick sand.
The alternative would be a cluster of small , (round) ,subsurface cavities .
I would expect these dimples,fill back up and disappear in a few hundred years.

Kye Goodwin


Posts: 1166

Reply: 108



PostPosted: April 28, 2011 6:45 PM 

The next week could be interesting. The next drive will probably reach a patch of plain that shows a Hirise texture unlike anything yet encountered. It might turn out to be unimpressive from the ground but from orbit it looks like an complete tiling of the plain with irregular elongated polygons.

Those two craters coming up look pretty interesting on Hirise too. (Thanks Horton for the animation.) They are not very circular and seem to have dark interior structures. They'll be "active" probably, young or old.

Ben, re your 106, That first crater is near Block Island, sol 2011.

hortonheardawho


Posts: 3465

Reply: 109



PostPosted: April 28, 2011 7:11 PM 

Today's drive ( sol 2581 ) should be starting within the hour. If you look closely ( original size ) at reply 104 you can see a band of darker soil ahead that must be the "tiled soil" mentioned in reply 107.

The darkness seems to be shadowed sides of a series of ripples running north-south?

Barsoomer


Posts: 344

Reply: 110



PostPosted: April 28, 2011 7:32 PM 

I think its a collection of neighbouring slightly lowered areas. Maybe shallow sinkholes? The "ripples" may be the unsunk ground in between.

From orbit the pattern doesn't seem particularly north-south.

Ben


Posts: 2270

Reply: 111



PostPosted: April 28, 2011 8:33 PM 

This small area looks like a thin layer of dark sand with a group of slightly elevated,zig-zag ripples . No clues!!

http://www.unmannedspaceflight.com/index.php?act=attach&type=post&id=24229

Ben


Posts: 2270

Reply: 112



PostPosted: April 28, 2011 10:42 PM 

Kye; Block island is about 5km from VC so it is questionable if that is the source. Confused

hortonheardawho


Posts: 3465

Reply: 113



PostPosted: April 29, 2011 7:58 AM 

sol 2581 ( Apr 29, 2011 ) guestimated map position:

See the Flickr comment for how this position was determined.

The distance to the near rim of 30 meter crater is now about 135 meters. The next drive ( today? ) could put Oppy almost there.

Barsoomer


Posts: 344

Reply: 114



PostPosted: April 29, 2011 11:28 AM 

Suppose the ground here gets a thin covering of frost most nights that disappears in the morning. What effect would that have on the appearance of the soil? Would it have any effect at all?

Psych Author Profile Page



Posts: no

Reply: 115



PostPosted: April 29, 2011 8:49 PM 

From what I have observed of earthly frosts, it does not seem to have much affect on anything at low altitudes and in low quantities. What effect should one expect at higher altitudes, latitudes, lower temperatures and lower moisture levels?

Fred


Posts: 73

Reply: 116



PostPosted: April 30, 2011 2:20 PM 


For the newbies,
Frost means saturation and fresh water at the surface. This leaves open frost melt and or brine formation and associated duracrust and chemical process. In other words it means everything.

Fred

Psych Author Profile Page



Posts: no

Reply: 117



PostPosted: April 30, 2011 6:12 PM 

Oops. I presumed the discussion was about the type of frost forming from warm moist air freezing on contact with a cold surface:
and then melting\evaporating\(sublimating on Mars?) as the temperature warms : . Seems the discussion may be about perma-frost.

Psych Author Profile Page



Posts: no

Reply: 118



PostPosted: April 30, 2011 6:15 PM 

Last image for above post:

These were all taken by me on a recent trip to Florida.

Ben


Posts: 2270

Reply: 119



PostPosted: May 1, 2011 12:57 PM 

The official conclusion now is that the ridges we discussed in 108-110 are inverted topography associated with fracture filling that is more resistant than the surrounding soft rock that has eroded away.

Makes you wonder why these fractures are filled w/resistant material and the others like them are trenches ??

Once a small area of ponded surface water ??

Kye Goodwin


Posts: 1166

Reply: 120



PostPosted: May 1, 2011 2:47 PM 

Ben, re your 117, If we get a look at that area of patterned ground it will be interesting to see if the polygons have raised edges or depressed edges. If your resistant fracture fill suggestion is right then the polygon edges should stand higher than the polygon interiors.

I've been having another overall look at the fracture "fills" and where we have seen them at Meridiani. So far it seems that the vast majority occur in "fractures" directly adjacent to areas of uniform fine sand, that is: "microchannels" as I have defined them. Considering that microchannels cover only a tiny part of the total interior soil surface of all fractures, I wonder what this strong correlation with the fills could mean?

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