Dark Streaks At Victoria Crater, MGS: MOC image Options

[SigurRosFan]

Release date: Today (12 October 2005)

http://www.msss.com/moc_gallery/r22_s04/im...2/R2200640.html

[Guest_Richard Trigaux_*]

The dark streaks were NOT on the previous photos!!!

Is is just a matter of wavelenth or of weather?

Note that endurance had a whitish streak leading S-E. It is still visible, but less. Now is a qark streak leading N-0 which was not on the previous images.

The direction of streaks may reflect the changes of wind. But why changes in color? Is it a matter of grain orientation relative to the sun light, or of mineralogy?? It is difficult to admit that wind blowing in the same place may eject a different material according to its direction.


And about Victoria crater...

It looks as if it was dug into... sand. As if the impact punched through a relatively thin layer of evaporites, into an underlying sand layer. Difficult to enter into such a place, except for two places on the west side.

[Zigtag]

It looks as if it was dug into... sand. As if the impact punched through a relatively thin layer of evaporites, into an underlying sand layer. Difficult to enter into such a place, except for two places on the west side.

I've been lurking here for quite a while. I'm not a scientist by any stretch of the imagination. So my observations are not as educated as those by others here. Sometimes though a step back and look from not so educated eyes can bring to light some 'unseen' things.

Is it possible that it isn't a crater at all? What about being a sinkhole? I don't have all the fancy tools you all have to process the images to look at height variation on the 'rim' to see if it is raised significantly or not. But is it possible that it is a sinkhole or collapsed caldera?

If it is a crater and with the lack of ejecta maybe it's a matter of the ejecta is there just buried under the loose 'sand'. Obviously there is quite a bit of material moving in this area as seen with the 'Tour de Dunes'.

[dvandorn]

Is it possible that it isn't a crater at all? What about being a sinkhole?

Possible, but unlikely. From above, the terrain around Victoria looks idenitcal to the plains where Oppy landed. And Victoria itself looks a lot like Endurance, just a lot larger.

And Endurance is pretty obviously an impact crater.

I think the difference between something like Erebus (which actually looks old and degraded) and Victoria or Endurance (which don't look nearly as old) is the state of the ground where the impactors struck. I think Victoria and Endurance were made well after the place dried out, and represent what happens when a crater is made in the "finished" evaporite layer (i.e., nothing has come along after those impacts to degrade them with the exception of wind). Whereas Erebus and other very degraded-looking craters were made back when the place was still wet, and further evaporite has been deposited on top of the impact features before the whole thing dried up and no more water was available to lay down more evaporite.

And, in response to Richard earlier, yes, those dark streaks *are* there around Victoria on earlier images. They're just not as pronounced. I'd bet it has something to do with sun angle and angle of incidience at the time each image was taken, as to the dark wind-blown dust streaks being more or less visible. And no, I doubt seriously they're made by dust devils -- there has been absolutely no sign of dust devils at Meridiani, and these streaks obsviously follow a pattern that shows they're formed by the aerodynamic disruption caused by the crater rim itself, so no need to conjure dust devils to explain them...

-the other Doug