http://www.msss.com/mars_images/moc/2005/10/24/

cPROTO Oppy:

That's great!

That position corresponds to the point where Oppy almost got stuck again.

Interesting. This 5 Oct image has a significant increase in resolution.

A couple of observations. There is a definite fabric to the ripple alignment: the primary direction at about N10W and a secondary at about N90W. I noted this in the 2004 image, but wondered if it was not a pixel-effect. There are lineations in the bedrock, and seem to be about N70-80W This is at odds with the anatolia lineations, which trend ENE.

Over the year's time span, the ripples rate of movement increases away from Erebus' rim. I thought first that this might be an animated GIF registration issue, but I think I can spot bedrock features that are in registration, so the ripples do move as such.

My initial observations, subject to revision...

--Bill

Up to now, the image around the Erebus crater and the way to Victoria aren't sharp enough to sketch a best route plan. This happens the same too for Gusev's zone where Spirit is facing a tough terrain.

What does happen with the lack of JPL's asking for support from Mars Express Orbiter team to take a nice picture around Erebus and Victoria craters?

Rodolfo

Well - MEX can do about 6 - 12m res in colour, but the suposed 1.5m res super resolution channel is really really crappy, and can actually get about half of that.

Given MEX's orbit and it's visiting of any one site on mars less regularly than MGS, and it's resolution to MGS, MGS is by far the better spacecraft to do this sort of thing.

Doug

Doug,

You are right about the MEX's orbit on Mars plays an important matter to as whatever will or not take pictures. I tought the MEX pictures quality and resolution are fare superior to MGS. Your statement has made me disappointed.

So now, both MER's will be playing with short views. Previously, I have put the importance to have a retractable mast on the rover in order to leave the dependence of orbiters's camera that is tied to their orbit trayectory that is not easy to change whenever it is needed.

Rodolfo

I don't agree with Bill about ripple motion. I think this effect is purely caused by misregistration and there is no ripple movement at all. I can not detect any evidence of bedrock features in registration. I'm willing to be proved wrong, though.

Phil

I agree with Phil on the ripple movement. Looking closer, I think that I was tilting at windmills....

--Bill

Hmmm... did anyone else notice the "2004 no labels" pic on the MSS site is incorrect -- its actually the 2005 image again?

I agree its an image alignment issue. Here's my attempt at the animated gif, with a better alignment achieved by rotating one image 0.4 degrees relative to the other.

Click to view attachment

It's OK, Bill, I've whacked a few windmills too! Doug sent me a horse's head after one particularly bad episode.

Phil

as far as getting a handle on how much the dunes actually do migrate over the seasons/years/eons, we should have plenty of years of comparative MGS data by now to get some ballpark estimate about this dont we?

im thinking someone has done a paper on this by now. anyone got a link?
(ill find it and post it here if i can steal some time)

The ground truth that we have from the rovers tells us that the dunes are evolving too slowly to see any motion from orbit. At best (with current res), we would have to wait upwards of a century to see anything. Probably longer...

I disagree. The ground truth shows that disturbed martian soil at Meridiani (as in disturbed by the MER tracks) starts blowing around after only a day or two. And it shows that the drift surfaces are not cemented.

The only thing that keeps the drifts from changing dramatically from day to day is an equilibrium that has evolved between the grain sizes and the winds' transport capacities. Change that equilibrium (for example, by adding a few tons of dust per square kilometer, say in a dust storm), and I'd bet the drifts will evolve much faster and more noticeably.

Of course, if this dust storm kills Oppy, it'll be sort of hard to show how the greater levels of deposition will affect the drifts...

-the other Doug

I disagree. The rovers have observed the same dune features for months with only the slightest changes. Those changes would have to continue for many decades to add up to one pixel shift from orbit. I'm sure what you think a sprinkling of dust is going to do. Or why you are so sure the dunes are in equilibrium.

Bottom line - There would have to be a major shift from the observed conditions to speed this process up to the point where it could be observed from orbit in our life time.

ed

Exactly. BUT: why should adding some dust to the surface change this ? The dunes are the dunes and adding more dust cannot alter the original dunes underneath that easy. The dust can accumulate on them, but it will be blown away more easy than the material of the dunes itself. Just like the only transportation of material we actually saw happening was the change in oppy's tracks. But this was in an unnatural (non Mars induced) circumstance: by crunching the topsoil that is "stripped" from its "finest fines" by eons of wind, fines from underneath are liberated and go there way immediately. To my point of view, that's what we saw happening within day's, but that's about it. We did not see ANY movement, not even with MI, considering the untouched surface.

I think these dunes are altered and formed in highly rare happenings of major windspeeds. And i think it took an unbelievable long time to form.

Besides: there's not a single reason why observations from orbit could add new insights about these processes....because not even Oppy sees it moving from a million times closer than any orbiter......