Dream Jobs and Mars Rocks (Shallow Thoughts)

Akkana's Musings on Open Source, Science, and Nature.

Wed, 12 Apr 2006

Dream Jobs and Mars Rocks

Driving home from dinner, watching the alpenglow fade from the gleaming domes of Lick Observatory, I found myself thinking about the talk last night: a wonderful geology seminar by Michael Carr of the USGS on the subject of "Water on Mars".

I had a chance to chat briefly with the speaker before the meeting. We got to talking about the moon. It turns out that he spent some of his early career at Lick, working with a few colleagues to make a geologic map of the moon. How? By sketching the terminator every night from the eyepiece of the 36" refractor, and trying to deduce the geology from the topography they sketched. Talk about dream jobs!

It was interesting to compare Carr's talk to the SJAA talk on the same subject earlier this year by Jeff Moore of NASA/Ames (always one of my favorite SJAA speakers). Carr's talk was quite a bit more detailed and heavier on the geologic details, not surprising since he was speaking to a room full of geologists and geology students. He even showed a stratigraphic column of the Burns Cliff area that the Opportunity rover investigated near Meridiani.

I learned quite a bit that I can apply toward my "Mars Rock" collection. I have a set of rocks that are similar to the various interesting rocks on the moon (I finally found some anorthosite a few months ago). I use them when I give presentations on the moon. It goes over very well: I think people get a better idea of what the moon is made of and how its surface looks when they get a chance to handle the rocks and look at them up close.

I have a start on a similar collection for Mars, but of course the most interesting Mars-like rocks to show people aren't the boring black and red basalts; they're the ones the Rovers have been discovering that point to a history of water. So those are the rocks I'm most interested in adding: the sulfates and other evaporites, sandstones made of evaporite sediments, hematite "blueberries" (Moqui Marbles, on Earth), and jarosite.

I'd never heard of jarosite before, but from a bit of web research the day after the talk, it turns out to be one of the minerals implicated in the controversy that was in the news last year about modern-day generation of methane on Mars. Some people attributed the extra methane to the presence of biological organisms, though others were quick to point out that there are plenty of non-biological ways to release methane.

Interestingly, one of the audience members at the talk commented that in the Sierras jarosite is a weak biological indicator (because the biological organisms prevent formation of carbonates, if I understood him correctly). So it's a pretty interesting mineral even for someone who doesn't hold out much hope for finding life on Mars.

Here's a good summary of the rocks found in the Burns Cliffs.

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[ 21:27 Apr 12, 2006    More science/geology | permalink to this entry ]