Changes at Low Ridge Haven |
Changes at Low Ridge Haven |
Sep 18 2006, 04:56 PM
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#1
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Senior Member Group: Members Posts: 4252 Joined: 17-January 05 Member No.: 152 |
It's been pretty slow in the Spirit forum recently, but hopefully this will reawaken it.
A new thin dark streak is visible in the latest sol 961 rear hazcam, that wasn't visible in the previous shot, from sol 924. It's visible in both L and R hazcam views. It looks remarkably like a dust devil streak, but the scale is very small. Here's the R hazcam from sol 894 subtracted from the 961 image: The dark streak cuts across more or less from left to right about a third of the frame down from the top. Other differences are visible, mostly around rocks, due to the change in sun angle between the frames. To demonstrate that the dark streak isn't just an effect due to that change in sun angle, look at these three frames: sol 856, local time 11:07 sol 961, local time 11:21 sol 894, local time 11:45 You can see that the shadows move progressively from the sol 856 to 961 to 894 frames above, as you'd expect from the local times they were taken. But if you flip between the three frames, you can see the dark streak only in the middle (sol 961) frame. If the streak were due to changing sun angle it would be at least as strongly visible in the 856 or 894 frame. Therefore it's not due to sun angle. As I said, this is way too small for a dust devil streak. And, I don't think we're anywhere near dust devil season. My guess about the origin of this is a small "crumble event" on one of those dark rocks in the upper left, followed by the normal winds blowing some dark dust downwind. Anyone know if the streak direction is consistent with what the winds should be doing now? Has anyone else noticed changes near Spirit? |
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Sep 19 2006, 05:59 AM
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#2
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Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
Yes -- with the flicker gif I can make out the change in albedo. I kept looking in the area of the streak that is apparent in the subtraction image, but by opening each image separately and just moving from one browser window to another, I honestly couldn't see the albedo change. With the flicker gif, I can see the actual albedo change quite clearly, even without the third subtraction frame.
-the other Doug -------------------- “The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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Sep 19 2006, 07:32 AM
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#3
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Senior Member Group: Members Posts: 2492 Joined: 15-January 05 From: center Italy Member No.: 150 |
Nice hypothesis, Fred.
I was looking for other Pancam images of this region, when I noted a huge DD track not previously visible in the eastern Eldorado! Original imagese were taken with PanCam L2 filter on Sol 924 and 961 (37 Sols apart), with almost exactly the same pointing and illumination: (start images are 2P208392405ESFAS00P2411L2M1.JPG and 2P211675276ESFAS00P2411L2M1.JPG). The track is already evident, anyway I made subtraction and used it also for a elaboration image showing the change over the first image through the hue/sat change: This story is encouraging, because we aren't yet in the DD season and, with some luck, one of these precursor could hit Spirit soon, making possible anticipated return to full rover activities... -------------------- I always think before posting! - Marco -
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Sep 22 2006, 10:47 AM
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#4
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Special Cookie Group: Members Posts: 2168 Joined: 6-April 05 From: Sintra | Portugal Member No.: 228 |
I was looking for other Pancam images of this region, when I noted a huge DD track not previously visible in the eastern Eldorado! Returning to this places makes me shiver... dilo, do you remember this images? It looks to be (in the image above) the same area you are making reference to, seems like this is a previliged DD corridor... -------------------- "Ride, boldly ride," The shade replied, "If you seek for Eldorado!"
Edgar Alan Poe |
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