[X] My Assistant

[nasaman58]

I just read on SPACE.com that Oppy managed to get all six wheels stuck deep in a sand ripple.


From the picture
http://www.space.com/php/multimedia/imaged...t%3A+NASA%2FJPL
the sand looks very fine grained, maybe a tad powdery. Squyers is optimistic they'll get out,
but it seems they'll have to do some rocking back and forth with prayers that they don't get in deeper. The taller ripples and the different textured sand is curious; any ideas out there as to why it gets that way farther south from the landing site?

I don't mean to be a cynic, but perhaps Oppy won't die of her own natural causes; maybe Mars, the god of war, has found prey....

[dot.dk]

I guess you havn't followed the 6-7 pages on the subject here
http://www.unmannedspaceflight.com/index.p...findpost&p=9426

The "news" is almost 4 days old now. But Space.com isn't that quick

[jamescanvin]

I guess you havn't followed the 6-7 pages on the subject here 
http://www.unmannedspaceflight.com/index.p...findpost&p=9426

The "news" is almost 4 days old now. But Space.com isn't that quick 

At least we have a dedicated thread for this now! It's a little ironic that the discussion has been going on in a thread named "Erebus/victoria Entry & Exploration, Would it be worth it?" when that question seems awfully premature given the current predicament!

I just wish I shared Steve Squyres optimism about Oppy, I'm worried sick! But I guess he knows best, here's hoping

James

[Marcel]

I better continue here, since Erebus and Victoria are faaaar away. Maybe we re-open it next autumn.....I couldn't sleep well last night. Maybe it is not nescessary, but the thought of a stuck rover that is functioning well got to me. Ah, we'll see, it probably is going to work out fine. Steve says so.

I used the time to do some thinking (also DVD, pay attention): the only reason why this happened has to do with the density of the material. It is considerably less dense than rocky soil, so it must be significantly higher in salt content, which is supported by the lighter colour and absence of blueberries. The white-ish mottled appearance in orbital images of the Etched terrain MUST be caused by locally elevated saltcontent of the material, instead of morphology. We're talking about physically wheatered (very finely fragmented) evaporite here! Evaporite wheathers easier than silicates, iron oxides or other mineral constituents. And that's exactly why we did not see any elevated outcrops on the way (nor on the horizon). The only outcrops we've seen is inside craters and at some points at the same level as the surrounding. The darker topsoil is definately much stronger (more resistant to wheathering) than the underlayment (evaporite). SO, i don't believe this fluffy material is global dust. It is formed in-situ.

Why ? Because there's forms of impact remnants in the white stuff on an regional scale (for example, Erebus). Therefore, the whitish material must have been there for a long time. While in the process of wheatering and levelling of, deeper parts got filled up with the darker material, mixing to some extent with the light stuff.

SO, there's only dunes here, all the way to Victoria (and probably further down). The fact that more and more (epsom?) salts are here, makes me think Oppy's on the edge of a former shoreline of some kind (lake, sea.....stream ?).

Oppy, follow the dark lanes please. It's safer !

[dvandorn]

I better continue here, since Erebus and Victoria are faaaar away. Maybe we re-open it next autumn.....I couldn't sleep well last night. Maybe it is not nescessary, but the thought of a stuck rover that is functioning well got to me. Ah, we'll see, it probably is going to work out fine. Steve says so.

I used the time to do some thinking (also DVD, pay attention): the only reason why this happened has to do with the density of the material. It is considerably less dense than rocky soil, so it must be significantly higher in salt content, which is supported by the lighter colour and absence of blueberries. The white-ish mottled appearance in orbital images of the Etched terrain MUST be caused by locally elevated saltcontent of the material, instead of morphology.  We're talking about physically wheatered (very finely fragmented) evaporite here! Evaporite wheathers easier than silicates, iron oxides or other mineral constituents. And that's exactly why we did not see any elevated outcrops on the way (nor on the horizon). The only outcrops we've seen is inside craters and at some points at the same level as the surrounding. The darker topsoil is definately much stronger (more resistant to wheathering) than the underlayment (evaporite). SO, i don't believe this fluffy material is global dust. It is formed in-situ.

Why ? Because there's forms of impact remnants in the white stuff on an regional scale (for example, Erebus). Therefore, the whitish material must have been there for a long time. While in the process of wheatering and levelling of, deeper parts got filled up with the darker material, mixing to some extent with the light stuff.

SO, there's only dunes here, all the way to Victoria (and probably further down). The fact that more and more (epsom?) salts are here, makes me think Oppy's on the edge of a former shoreline of some kind (lake, sea.....stream ?).

Oppy, follow the dark lanes please. It's safer !

Exactly -- the evaporite layer was created as a body of water evaporated (repeatedly -- since there are many, many layers of evaporite) and deposited the salts and minerals suspended within the water. Since it's been a long time since there were bodies of open water on Mars, the evaporite layer has been there for a long time.

But I don't necessarily agree that there are nothing but dunes as we get farther south into the etched terrain. If you look closely at the super-resolution MOC images, you can make out the duning pretty clearly, and as dunes always do, they are alined and controlled by wind patterns. The lightest-albedo structures within the etched terrain are very definitely not alined along with the other visible dunes -- they are more like small ridges and "peaks" sticking out above the plains. More importantly, they *interrupt* the regular procession of wind-formed duning.

I'm not saying that these high-albedo structures are nice, clean, unmodified outcrops of pristine evaporite. But I think they are evaporite structures in the process of being weathered away. In which case, they'll probably look like big piles of very light sand with actual rock sticking out at various angles (and weathered rather smooth). I think there *may* be some relatively uneroded evaporite exposed as a ground layer around these little ridges, which is what I'm most interested in seeing and getting analyses from...

-the other Doug