A Tough Grind

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Caption:

NASA's Mars Exploration Rover Spirit took the four images that make up thismosaic with its microscopic imager on sol 82. The mosaic reveals thedrilled surface of the target called "New York" on the rock dubbed "Mazatzal." The rock abrasion tool ground for 3 hours and 45 minutesto create this 3.8 millimeter-deep (0.15 inch) hole. The exposed areais 4.5 centimeters (1.8 inches) in diameter.

Mazatzal was an interesting rock to grind because it has a lighter tonethan the previously ground rocks "Adirondack" and "Humphrey," and becauseit looks different from its surrounding environment. Scientistshypothesized that Mazatzal's surface might be covered with a rind ofweathered material. They drilled through this very top layer to revealthe underlying rock.

Because Mazatzal's surface was not even, the left half of the rock waspenetrated more deeply than the right. As can be seen in this image, theright, darker portion of the rock is still covered by the rind material.Spirit completed a second grind at this location at a different angle toremove the remaining veneer from the right side and create an even deeperhole. Images of this second grind will be sent back to Earth in the nextsol or two.

After the Final Grind
The image was acquired on sol 85 after the rover drilledinto New York a second time with its rock abrasion tool. Remnants ofthe dark grey coating that covers Mazatzal's interior can be seen at theright side of the hole. The crack in the rock may have once containedfluids out of which minerals precipitated. Each image making up thismosaic is 3 centimeters (1.2 inches) across.

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