Don't recall the specifics but after we backdrove the RAT brushes we did in fact scratched the surface on occasion. The RAT and DRT brushes are completely different shape and the MSL arm is much heavier than the IDD.

Paolo

Thanks for the quick and authoritative reply, Paolo! I'm interested that the arm weight is relevant- does the arm actually support some of its weight on the rock surface while brushing?

John

We also want to get all the images down. Sometimes files are missing or incomplete and retransmissions have to be manually commanded, so there's some planning delay. I'm not sure what the story was with this particular image; it showed up before I could check.

The MSL brushes look a lot more substantial than the MER brush. Also, it looks like the MSL bristles (on one brush?) are angled so the wire bristles contact the surface vertically while the MER bristle tips touch the surface at an angle. Just my interpretation of these two images.


http://leakarea.com/headlines/super-robot-...o-the-mars.html


http://marsrovers.jpl.nasa.gov/gallery/pre.../20040202a.html

You are correct that a lot of limestones on Earth are fossiliferous, but limestones can form naturally outside of biology as well. As you really need is liquid water, the right PH and lots of carbon dioxide. Mars has lots of CO2, but did it have liquid water at the right acidity?

I have to ask - Is that wheel going to be OK - from what I see in the Sol 151 NavCam shot?

http://mars.jpl.nasa.gov/msl-raw-images/pr...NCAM00352M_.JPG

These dents were noticed right after the first drive way back in the day. They've been accumulating ever since. We were told that it won't be an issue.

Opportunity's bristles after the unfortunate backdriving now have a shape similar to this but you are right, MSL's are more substantial. And yes, the MSL Arm holds most of its weight while brushing, it is way too heavy for the DRT tool.

Paolo

Well the nontronite layer indicates neutral to higher pH water so with that, a CO2 atmosphere and probable anoxic environment it is difficult to see a scenario where iron/magnesium carbonates would not form, although survival of exposed deposits during the acidic period would be problematic.

Very Nice Damien. One thing I noticed after I posted my final version, was the white balance was wrong on part of my final version. I'm gonna have to fix this. But yours is splendid!

The color of Ekwir_1 looks to me similar to that of gypsum;
its hardness, at least at the surface, looks to me similar to that of gypsum (from the scratches);
the conditions, when the rock formed, were probably in favour of the formation of gypsum.
So I'll be positively surprised, if gypsum does't turn out to be one of the three most abundant minerals in Ekwir_1, besides colloidal silica and a second sulfate (iron(III)-sulfate or magnesium sulfate) or even bisulfates.
Interesting to me will be the crystal water contents, and the less abundant minerals and salts, as well as the D/H ratio of the crystal water.

My present imagination of the conditions, when the rock formed, is an acidic (from sulfuric acid) and saturated mud (because of bubbles and veins) of sulfates and colloidal silica.
That's my expectation, and I hope I'm wrong and clay minerals will be found, at least kaolinite.

The lower layers of Mt. Sharp will be a better place to look for nontronite or carbonates, imho.

His work really is. I can not get a consistent light balance on my panoramas. But Damien's work is just awesome. Gets it every time, especially some of those NavCam mosaics. Ed Truthan and Airbag have great stuff too!

Sorry for the tangent.

Thank you both To be honest, I don't touch a pixel of the white balance, I'm just adjusting brightness between frames .

Get back to some Navcam imagery, with Sol 151 panoramic around the rover :

Damien, votre mosaics sont vraiement formidables, comme toujours!

On your French website you give a hint to the track of the rover, where lots of rocks are visible, which were broken during the drive. This observation may be useful to further investigate the interior - and thus less weathered parts - of the rocks, and it may provide more information about their hardness. Therefore I repeat it here in English.

3-channel color-enhanced near infrared false-color image of sol 150 Mastcam Right:

from images as red, as green, as blue.
Due to strong color-enhancement, jpg artifacts become visible.
An animated greyscale gif, that shows, how brightness changes locally with wavelength - from blue to the farer infrared - might be interesting, as well: