Very nice, ElkGroveDan.

I am sure Mr. Armstrong would be pleased.

Craig

Dan--Applause!!! You should really do this more often; you have a talent!

I wonder if anyone else noticed what looked like deposits of ice at the bottom of the slopes (we'd call them talus deposits if they were soil) in Cartrite's mind-blowing images. If that's what we're looking at, we've got further evidence that this is an avalanche and not something else, and that the material doesn't all sublime away as CO2 turns from ice to gas.

Maybe a seasonal monitoring of changes at the foot of the slope would give further insights into what that stuff is and how it gets there.

Steve M

Definitely noticed them. As far as seasonal variations, if you look at the "before and after" animation from this post, imaged February 3rd and 19th 2008, you can already see dramatic changes, with most of those white deposits at the bottom gone and also much of the light stuff at the upper part of the slope missing in the later frame. Presumably this is due to evaporation as we head into northern spring.

But I (as a complete non-geologist) can't see how the white deposits at the bottom could be avalanche deposits without there being light deposits on the slopes just above them, left behind as the avalanche rolled down. Or is the idea that the avalanches didn't come from high up on the slope, but instead came from a collapsing overhang/cliff at the very bottom of the slope, just above the white deposits? Perhaps the clouds of ice/dust worked their way upslope with the winds?

Using the two frames in the post I refered to as a 3D pair I see no evidence of a steep dropoff at the bottom. The slope looks pretty uniform between the white deposits at the top and bottom. It would be great to have full resolution 3D views of the slope, so we could see for sure where the steepest part was.

Most interesting would be to have full resolution before/after pairs that showed changes (missing chunks?) on the slopes.

Agree with Ant 103 for the global colors.
Here is my own version, maybe a little more yellowish-brown in hues, after calibrations on some icy spots on the JP2 product also...
Enjoy !
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Beautiful work, VM!:)

Okay, I think I figured out what we all want for Christmas: a Mars Transient Event Observer (MTEO).

MTEO would be placed in a Sun-synchronous polar orbit. Its payload would consist of a multispectral sensor suite (selected IR to visible) and a humongous set of solid-state data recorders (as many gigs as we can stuff onboard). Operational concept is that it stares down 24/7, continuously acquiring data...almost all of it being discarded a few seconds after acquisition. The cool feature is that there would be a moving target detection algorithim in the imaging software that would detect rapid changes, and trigger a 1-minute movie grab (combined with target lock) that would be stored for downlink, including the first few seconds of coverage immediately preceding the event.

MTEO would provide enormous insight into known presently active Martian geological and climactic processes, and potentially could discover many others. If the mission had sufficient longevity, it might even capture rare events such as meteor impacts.

Now, give me some money! (Actually, somebody in academia please take this idea & run with it!!!)

Don't mean to rain on your parade, but it doesn't seem like it's worth the cost and significant technical hurdles. After all, we don't even have that capability for Earth, and yet geologists manage to figure things out.

And call me a skeptic about these being avalanches as opposed to some kind of longer-duration wind phenomenon. Probability alone would argue against having caught such a transient thing in an image that took a few seconds, at most, to acquire.

I fully agree with you Mike. As I pointed out, an avalanche, on Earth, last a matter of seconds so, there's no way it could last long enough on Mars for MRO to be able to pick so may of them. So, I see two possibilities :
1- wind effect near a cliff...but, if you look at Olivier's rendering, the "avalanche" is clearly denser in the center so it as to be a kind of swirl or a big dust devil.
2- a "real" avalanche of whatever material that blows a lot of dust up in the sky. I even wonder, on Olivier's picture, if the dust if not going UPHILL.
Problem is : if the dust is regularly blown out, it has to come back again form somewhere. Is the area a dust trap ?
Olivier, your picture est juste incroyablement précise, thanks.
Thanks Dan for your wonderfull world.

Looking in detail at the downslope "talus" deposits I mentioned before, there seem to be some clear indications of the interaction of the avalanche material (frozen CO2 or H20) with the rocks at the bottom of the slope. The deposits on the right are in lobate patterns that seem to reflect channels between the rocks immediately above them on the slope. A plausible explanation is that an avalanche is being funneled through the gaps between the rocks and coming out in jets that deposit in lobes on the surface. The same thing seems to have happened on the left, although the rocks are not clearly visible. In the center, right behind the cloud there seem to be puffy streaks, that could be the ice settling out to form another lobate deposit -- as it were, caught in the act.

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Looking further up the slope directly behind the active avalanche, there seem to be some light deposits that haven't yet had time to evaporate or sublime away. Those little details add to the picture of an avalanche of some sort.

As to the probability argument, there are enough deposits in this image to suggest that this is a regular annual part of the melting process. If this is CO2 ice, it would make sense that sublimation would knock more solid pieces loose than would the melting of ordinary water snow in terrestrial mountains. This could be a common event on Mars.

Steve M

This lobe and ridge pattern is repeated several times as you move up from the bottom of the image to the top of the image. The deposits are dark instead of light. For example, look at the ridge directly above the label "Recent" on your picture. It looks to me that there is a process at work that is not just happening at the bottom of the biggest cliff face.

I was recently in Vanoise (French Alps) for a glaciar trecking and I've find the following analogies with the Avalanches on Mars (without the actual avalanche )

Mars
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Analogy
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Context
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Unnecessary quoting removed. Mod.

Well actually this is the reversed situation.