Changes at Low Ridge Haven Options

[dilo]

ok, let's wait for next images...

[fredk]

I identified the putative source region of the dark streak in pancam imagery. Since the streak is darkest on the left end, I'm guessing that's near the source. That end is between the red, green, blue, and yellow marked rocks in this crop of the sol 961 hazcam:

Here's a crop from James Canvin's (stunning!) McMurdo pan, where I've identified and marked those same four rocks:

I've circled the area corresponding to the left end of the streak.

It's pretty clear what may have happened here: a piece of the very thinly layered outcrop fell down onto the sand below, kicking up loose dust. There are a number of potential loose pieces, such as the one I've arrowed.

Boy, would I love to see some new pancam imagery of this area!

[dvandorn]

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

[dilo]

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...

[climber]

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:
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...

That's something !
I note that, pending the hypothesis of a DD is right, the direction it took would have bring it little bit South of Spirit but not that far. Since the DD desapears in the depression on the other side of the ridge we loose its track. But if it has continued, it should be visible on some images taken in the South direction. Do you agree on this? Do we have such images ?

[dilo]

That's something !
I note that, pending the hypothesis of a DD is right, the direction it took would have bring it little bit South of Spirit but not that far. Since the DD desapears in the depression on the other side of the ridge we loose its track. But if it has continued, it should be visible on some images taken in the South direction. Do you agree on this? Do we have such images ?

Dunno... My impression is that dust devil had effect only on Eldorado dunes, terrain outside wasn't disturbed. If I'm correct, based on prevailing wind direction in old DD movies, devil's direction was toward South (toward Spirit) and the intriguing fact is that terrain in the foreground (the Homeplate, essentially) changed slightly overall hue in the last picture, suggesting a similar (weaker) darkening occurred!
However, if DD invested Spirit, I imagine we should have more whrs now (and a lot less dust on solar panels)...

[Tesheiner]

Climber & Dilo,

Be careful!
Spirit + DD ==> cleanup-event = Doug jumping off its seat.

[Bill Harris]

This is not necessarily a dust devil in the usual sense but simply a turbulent swirl in the atmosphere as the wind rounds the Husband Hill obstruction.

--Bill

[climber]

Climber & Dilo,
Be careful!
Spirit + DD ==> cleanup-event = Doug jumping off its seat.

I know we are walking on eggs here (dunno if the expression works in english, actually, it's a french one )
1-it's not because it didn't happen before that it'll not happen
2-I took some precautions before on a post here above
3-we all know it's a remote possibility
4-the first one to spot such an event will win THE gran price

PS : I'd better like dust jumping off solar panels that Doug out off his seat (don't like " unecessary post deleted")

Edit : you're right Bill, a kind of dd instead of DD.

[helvick]

I don't want to seem like a spoil sport but I feel the need to reiterate that there has been absolutely no evidence of any dust removal activity at all recently from Spirit's solar panels. Zero, nada, zip. Power output has followed the expected mid winter insolation curve with no additional dust deposition (which is good) but no dust removal either over the past six weeks or so. That was up to Sol 957/958. The next power update might change that but for now any speculation about cleaning is a bit premature.

Opportunity has scored a noticable (~20%) power benefit from something recently, presumably a cleaning event or events but that is not yet clear.

[fredk]

Nice find, Dilo!

I have to wonder like Bill Harris if this isn't a dust devil proper. The thing is, we know that there's something unique about the topography associated with Eldorado, since we have the rippled sands there. Could we have captured here a step in the normal buildup of Eldorado?

It's also interesting that the track ends (or starts!) at the edge of Eldorado.

But still, remember we're seeing Eldorado quite foreshortened here, so the track is actually quite long and thin (and probably longer still - we can't see the other end of it). That to this non-expert sounds like a devil or something very close.

[ustrax]

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...

[dvandorn]

The darkening in El Dorado isn't very long -- it likely was caused not be a dust devil, but by a seasonal change in the direction and speed of the local winds. At least, that's what I would suggest, barring any evidence that dust devils actually occur during mid-winter here in Gusev.

-the other Doug

[dilo]

Eh, Ustrax, not only I remember these images... in fact, I was inspired by them in searching changes inside Eldorado! I remember also our wild theories about these features (cracks in a lake made of lava or something else...).
About other Doug's explaination, the absence of any trace outside the dune field is suspect, but also a seasonal wind change impacting a so delimited region is a little hard to accept, IMHO...

[slinted]

Is there a second image to confirm the darkening? This seems *very* early in the season for there to be dust devils (the shape of the ground track seems wrong too). Strong gusts could be responsible, but I wanted to throw out another possibility.

Given that Opportunity has recently seen some clouds, could this darkening be a cloud shadow projected on the ground?

edit: So, the changes are real and lasting, as evidenced by this L1 image taken on sol 969.