[X] My Assistant

[mhoward]

Bunch of MI's of the "rind" (mentioned in Steve Squyres' latest mission update), I believe, starting with this one:

http://nasa.exploratorium.edu/mars/opportu...DIP2956M2M1.JPG

Forward hazcam:

http://nasa.exploratorium.edu/mars/opportu...DIP1110L0M1.JPG

[Bill Harris]

We're starting to see some interesting things there.

From Sol-556 (the same time as MHoward's FHazcam shots), we have a Pancam shot off to the side of this outcrop we're on:

http://qt.exploratorium.edu/mars/opportuni...DIP2584L7M1.JPG

A couple of observations: the weathering rind is dark, with a similar value as the sand. You can see an area just left of center where the crust is wind-eroding down to the underlying evaporite. And notice the HUGE blueberries on the left side and below center. They must be in the 10-12mm range!

This is what I suppose: a thin blueberry-sand covering is over the evaporite bedrock and protects it from aeolian erosion. But this covering is thin enough that the bedrock is heated by the Sun and can pick up some water from surface condensation. This is a good setup for chemical weathering; heat and water, and the weathering crust is protected from erosion and can continue to "cook" for a long time. The thin sand shifts and we are observing a freshly-exposed weathering surface.

I think this is why we saw that dark ejecta and the dark floor at the heatshield impact bonk. My thoughts were that was a weathering surface and I was disappointed that we didn't look closer then; hopefully, we will now. It will be interesting to know the minerology of the weathering crust.


--Bill

[abalone]

Where have all the blueberries go, seems to be only one in the middle? I assume this is a grind of the rind.

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