[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 !

[maycm]

Steves latest update.......
from http://athena1.cornell.edu/news/mubss/

April 27, 2005

A note to all you Opportunity fans: Get used to the current scenery, because we're going to be here awhile.

We are very optimistic that we'll be able to get out of here, but we're really going to take our time doing it. The first rule in a situation like this is "do no harm", which means that you don't rush anything. We're going to take lots of pictures of all the terrain around the vehicle, to get a very complete picture of the situation. We're going to do lots of testing with the rovers that we have on the ground to simulate the situation on Mars. This testing will be aimed not just at finding a plan that will work, but at finding the very best plan that will work. We may try quite a few small maneuvers with Opportunity that aren't intended to do anything other then help us gather more information... perhaps followed by even more testing. All of this is going to take a lot of time. But this is a very precious vehicle up there, in excellent health, and there's no reason to rush anything. I'll try to provide updates as the process moves forward, but the main message for now is to be very, very patient. No apparent progress in the images doesn't mean anything other than that we're being very careful to do our jobs right.

[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

[djellison]

http://www.unmannedspaceflight.com/doug_im...o448_tracks.jpg 580kb

Doug

[Bill Harris]

Great image, Doug.

What do we see here? The duricrust seems to support the weight of the Rover as usual in the top third of the image, but apparently the wheels break through the surface and start churning after that point. The material below the surface is powdery but cohesive. One thing I don't understand is why the surface material seems to "squoosh" out from under the wheels, as in the middel of the top frame of this combinatin, and seen better in some other images.

Strange stuff. But I think this change in characteristics is significant.

--Bill

[Nix]

A CRACKING image, as you would say. Terrific detail!
Bill, couldn't it be they ran the wheel in the reverse direction at the point you mentioned? Or the wheel stalled for a moment?

[Bill Harris]

Something definitely happened at that point in time. As we examine and analyse (we'll have time to do that _ad_nauseam_) we'll figure out what is happening. I suspect that we've been seeing differences in the soil profile here; the soil in this part of Meridiani is very thin anyway and the "A" horizon is the ubiquitous blueberry/sand/weathering byproducts so we aren't sure of what is just beneath our wheels. I'd volunteer to do some shovel trenches, after extricating our intrepid hero...

--Bill

[Bob Shaw]

I'd wager that what we're seeing in Doug's image is, at the transition between the two sorts of materials, a clod being pulled up onto the wheel and then another, then another, until suddenly the spaces between the clods start to fill and the wheel becomes wholly covered (and rather smooth). The way that there's a cyclic pattern which drops off into chaos at the end is *not* good, for it implies that the wheels are going to perform quite poorly when the time comes to try to get out of the rover-trap.

[wyogold]

It almost reminds me of a snow crust. When you walk on it you are supported untill you hit a thin spot then suddenly your stuck up to your waist in a snow bank.
maybe the rover needed snow shoes.

[Tman]

I sought a view of this "funny dune" that Oppy maybe took sols ago. The next sol back with useful pics that I found is sol 439. I've made a Pancam-pan from this sol therein one can find this dune. Additionally I've labeled it in a smaller image, cut from the pan - with the "exact" site of crime , where I think it is.

Panorama (720KB) http://www.greuti.ch/oppy/oppy_sol439_pancam.jpg

Cutting http://www.greuti.ch/oppy/the_funny_dune.jpg

You can compare it by the Navcam pics from sol 439 http://marsrovers.jpl.nasa.gov/gallery/all...unity_n439.html and by my Navcam-pan of sol 446 http://www.greuti.ch/oppy/oppy-sol446-navcam-k.jpg

[Gray]

I'm not sure if anyoone has pointed this out, but if you look at the most recent front and rear hazcam images, it looks as if the rover was crossing a ripple at a very low angle. When it has crossed ripples earlier it was at an angle nearly perpendicular to the crest. The crests of the ripples are somewhat sinuous. The rover started across this one at a low angle to the crest. At about the point where the rover was crossing the crest of the ripple, the crest curved towards the left. The effect was that all of the left wheels ended up on one side of the ripple and all of the right wheels were on the other side of the crest. All six wheels ppear to be in the deepest (softest?) part of the ripple.

[Bill Harris]

I sought a view of this "funny dune" that Oppy maybe took sols ago.

Good find. The "chalk outline" of our victim is a nice touch.

One observation: Look at you panorama and just before the scene of the crime I see an Anatolia-type of lineation immediately before the funny dune. This may not be relevant, but I noticed this first off. Also, there seems to be some layering in the dune just left of center.

Many clues here, Inspector Cleuseau...

--Bill