Slashdot Mirror
Spirit Grinds Adirondack, Looks for Iron
Quantum Jim writes "Space.com reported on Friday that Spirit used its Rock Abrasion Tool against a Martian rock dubbed Adirondack. Although the rover spent three hours grinding the rock, it was only skinned by about 2.7 mm. Scientists say this is due to an unexpected amount of resistance. Spirit is currently standing by for ground contollers to deactivate a safety feature so it can be repositioned"
The last time we were roving around on another planet and looking at rocks during Apollo 17, the world responded with a collective yawn. Better to bring your golf club like Alan Shepard. Now that's exciting! You can hit a one-handed seven iron like 1000 yards...
Who do you get to be an expert to tell you something's not obvious? The least insightful person you can find? -J Roberts
That's because the apparently foliated structure of the Meridiani outcropping could have arisen from other processes than sedimentary deposition. The parallel channels shown in the outcropping could easily have arisen from steady weathering in an environment dominated by a single wind direction, for instance.
In fact, interpreting them as sedimentary would require some pretty radical planetological claims: (a) a long-lasting supply of deep water in which sediment could accumulate into mudstone or sandstone, (b) a long-lasting influx of water to carry the sediments in, and (c) a mechanism for exposing an outcropping, whether through wind-driven erosion or seismic activity which would not wear the formation to the level of the surrounding sand in the period of half a billion years.
If you want to be excited by them, talk about their observable features (foliation, heterogenous grain size, polarization proerties), not about their genesis. We don't have the evidence to conclude they're sedimentary, much as we would like to do so.