Nature of Victoria's dark streaks, swept clean, deposited, or other? |
Nature of Victoria's dark streaks, swept clean, deposited, or other? |
Guest_Sunspot_* |
Apr 21 2007, 09:45 PM
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#301
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Guests |
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Apr 21 2007, 09:49 PM
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#302
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Founder Group: Chairman Posts: 14434 Joined: 8-February 04 Member No.: 1 |
That's his current take - not the official definative answer.
Doug |
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Apr 22 2007, 04:36 AM
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#303
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Senior Member Group: Members Posts: 2173 Joined: 28-December 04 From: Florida, USA Member No.: 132 |
Come up with a believable mechanism by which contact with the arm could have generated the *opposite* result to what we've seen every other time it's been pressed into the soil, and I'll grant you the point. Opportunity was futzing around in that spot for several sols with its IDD. The grains there are not as cohesive, perhaps due to a lack of dust, so impressions don't take. All the pressing and brushing of the IDD caused a brazil nut effect, bringing additional berries to the surface. Lets also assume an optimum depth of loose material over bedrock for this effect, whatever depth that is... |
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Apr 22 2007, 04:44 AM
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#304
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Senior Member Group: Members Posts: 2173 Joined: 28-December 04 From: Florida, USA Member No.: 132 |
Come up with a believable mechanism... Or.... the finger of berryless sand that Opportunity was investigating was not a flat surface feature, but a tiny ridge of windblown material extending out from the tip of the rock. Opportunity's investigations flattened out this ridge exposing berries that were within or below it. Again, due to its lack of dust and fine particles, the sand flows as a liquid: marks and impressions are not easily retained. |
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Apr 22 2007, 06:36 AM
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#305
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Senior Member Group: Members Posts: 2228 Joined: 1-December 04 From: Marble Falls, Texas, USA Member No.: 116 |
I'm happy to hear that Jim's preliminary assessment is favorable to cleaning, but the real excitement tosol seems to be the remarkable change between sol 1145 and sol 1148 MIs. That is an unexpected change. That little ripple that was on the lee side of the rock is now mostly gone. There is a dent in the area from an instrument that might have disturbed the soil, but I also see dust being removed from other areas well away from that disturbance. Could the proximity of the instrument package, IDD, and rover have altered the local wind vectors here, causing that fine stuff to blow away?
This was bewildering me tonight until a friend sent me a link to http://www.flickr.com/photo_zoom.gne?id=466694284&size=o That's quite a clincher. It seems pretty clear that it is windy here. I think Oppy should configure it's movable parts to create the maximum wind turbulence toward its solar panels. -------------------- ...Tom
I'm not a Space Fan, I'm a Space Exploration Enthusiast. |
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Apr 22 2007, 06:50 AM
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#306
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Senior Member Group: Members Posts: 2173 Joined: 28-December 04 From: Florida, USA Member No.: 132 |
This was bewildering me tonight until a friend sent me a link to http://www.flickr.com/photo_zoom.gne?id=466694284&size=o That's quite a clincher. It seems pretty clear that it is windy here. That's a great show of the appearance of previously hidden berries, but I don't think it shows any results of short term wind action. I think the "dust" you see in the color image is really the result of lower contrast and lack of focus. In the black and white image the contrast and focus jump and make it look like dust has cleared. I look around but do not see the appearence of any previously unseen berries anywhere but at the sandy spot the rover was looking at next to the rock. I think the IDD was placed there specifically to get a look at built up windblown material with no berries and the activity of the IDD caused the sand to slide or shimmy away revealing the berries. |
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Apr 22 2007, 08:33 AM
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#307
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The Poet Dude Group: Moderator Posts: 5551 Joined: 15-March 04 From: Kendal, Cumbria, UK Member No.: 60 |
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Apr 22 2007, 11:49 AM
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#308
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The Poet Dude Group: Moderator Posts: 5551 Joined: 15-March 04 From: Kendal, Cumbria, UK Member No.: 60 |
Pile o'rocks...
...meteorite, you reckon? If so I'd love to get stuck into it... what a great strewnfield to study and gather specimens from! -------------------- |
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Apr 22 2007, 01:03 PM
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#309
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Member Group: Members Posts: 133 Joined: 3-June 06 From: the jungle of Nool Member No.: 799 |
sol 1144-1149 L247:
Maybe Oppy should stick around here for a while. And here is the L234567 color version of my animation CosmicRocker's friend sent him. |
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Apr 22 2007, 02:45 PM
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#310
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Senior Member Group: Members Posts: 4256 Joined: 17-January 05 Member No.: 152 |
Horton, that flicker gif of Alicante is exactly what I wished I could do! Thanks for that!
Rocker, what about the flicker gif convinces you it's windy? We do know it's windy, recall the light dust blowing out of the rover tracks. But it seems quite a stretch to say wind exposed these berries. |
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Apr 22 2007, 02:58 PM
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#311
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Senior Member Group: Members Posts: 2173 Joined: 28-December 04 From: Florida, USA Member No.: 132 |
OK, now I see berries moving in the wind. I see a group of small berries just off the 10 o'cock position of the sundial ball. I see several large berries along the very top, right of center, in the image. I see others moving here and there, all to the right, and down a little. I can't think of anything but wind moving them. But why no "cleaning event"? GREAT WORK HORTON! |
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Apr 22 2007, 03:13 PM
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#312
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Senior Member Group: Admin Posts: 4763 Joined: 15-March 05 From: Glendale, AZ Member No.: 197 |
This was bewildering me tonight until a friend sent me a link to http://www.flickr.com/photo_zoom.gne?id=466694284&size=o That's quite a clincher. It seems pretty clear that it is windy here. I think Oppy should configure it's movable parts to create the maximum wind turbulence toward its solar panels. Holy smokes...so what's going on with the power output? -------------------- If Occam had heard my theory, things would be very different now.
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Apr 22 2007, 03:33 PM
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#313
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Dublin Correspondent Group: Admin Posts: 1799 Joined: 28-March 05 From: Celbridge, Ireland Member No.: 220 |
Jim Bell's comments yesterday were accompanied by colour pancam's and an MI that seemed to me to indicate that the dark streaks were areas where cleaning effects predominate resulting in a surface layer that is more densely populated than average with blueberries that are themselves very clean. He was very specific about the terms "swept clean" and "polished surface's" when describing the areas but as Doug says these were just comments and not definitive rulings. That said his comments seemed to me to be a strong endorsement of the hypothesis that the dark streaks at Victoria's northern edge are caused by cleaning not deposition. He didn't comment on other areas that seem to be composed of dark materials that have been mentioned in this thread by the way.
I think the nature of the annulus (a very flat smooth surface with a relatively durable surface layer with lots of blueberries) is a major factor here. Whatever long term process that has created it must be compatible with the short term effects - if deposition of darker dust\sand scale material is the dominant cause then it should dominate the entire area eventually as the crater has changed shape and eroded back. What we actually see on the ground is the effect of MY\GY of very gradual erosion of both the crater and the original ejecta debris field that has lead to this very flat blueberry dominated crust where finer materials (dust\sand scale) are preferentially removed by the wind. |
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Guest_Edward Schmitz_* |
Apr 22 2007, 06:03 PM
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#314
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Guests |
The animation of the wind action between 1144 & 1149 is dramatic. Not to disregard Jim Bell's remarks... If the wind is this strong here, what's it like at the mouth of the bay? It appears to be capable of moving berries. Shouldn't it be moving the dark matterial in the bays and below the cliffs? And if that's the case, is there any way it would not end up in the streak area?
It has crossed my mind that the polishing of the berries might be a contributor to the darkening... |
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Apr 22 2007, 06:26 PM
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#315
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Senior Member Group: Members Posts: 2173 Joined: 28-December 04 From: Florida, USA Member No.: 132 |
Shouldn't it be moving the dark matterial in the bays and below the cliffs? Yes it should, if there is any "dark material" there to begin with. Otherwise it will move all the sand -- light and dark -- and completely clear away the dust. Still, I don't see any unique "dark material" in any of the latest images. |
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