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 18 2006, 08:37 PM
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#2
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Senior Member Group: Members Posts: 4252 Joined: 17-January 05 Member No.: 152 |
Dvandorn and anyone having trouble seeing this in the original images, here's a 3-frame gif that should help. Frame one is sol 894, unprocessed. Frame two is sol 961, unprocessed. Frame three is frame 2 minus frame 1, and then brightened:
[attachment=7492:attachment] Look for the (subtle!) change between the first two frames at the position of the streak in the difference image (frame 3). It's subtle but I was able to spot it before I made the difference image. As I said above, I doubt this is a devil. I think small "crumble event" followed by ordinary winds is our best bet. I think we expect some level of steadyish winds all winter? |
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