Arizona in the sky (with water)

So we're waiting for the latest news from Opportunity at the big press conference later today. My guess is that it's about the setting for the water and that they'll argue that it was a big old lake or sea on the basis of the sedimentology, a guess based mainly on the presence of sedimentologists John Grotzinger and David Rubin on the panel; Rubin is an expert on the cross bedding structures in sedimentary rocks that reveal currents, wave action and the like. (If it was about life they'd have Andrew Knoll on the platform). Since people have been kind of assuming that the rock was laid down in water, rather than altered hydrothermally, for a while, the announcement may not come as a great shock. As I suggested before, it would be nice to know whether the water was ice-covered or not, and evidence of wave action might settle that. But even there the chemical similarities to evaporite sequences Ben Clark talked about at the last big announcement seem already to have edged us towards the open water idea. (I say this because it's not obvious to me how an evaporite could be formed under ice; but then, on earth, evaporites are diagnostic of high temperatures anyway, so it wouldn't occur. Mars may have tricks that make it possible. And if it *was* obvious to me how these things worked, then it would all be much much less fun.)

Meanwhile Spirit is taking a poke at a more interesting looking rock than any it's seen so far, inasmuch as I can tell. It's quite big, perched on a crater rim and looks to have an unusual texture, which all sounds good.

This new rock has been named Mazatzal, after the mountains in Arizona (which, it must be admitted, are prettier). People are always seeing Arizona on Mars, and vice versa, adding romance, misconception and relevance to our view of the planet in various proportions over the years. This predilection that was the subject of the aptly named John Carter McKnight's thoughtful talk entitled "Barsoom's legacy: Mars Through the Lens of the American Southwest", given at the Contact conference held at NASA Ames ten days ago. Although I was only able to be there for one day, I thought it was a terrific meeting, with many good talks and some great visual presentations. It was particularly nice to see Kees Veenenbos (check out his lovely topographically correct renderings and animations), who provided some gorgeously frosty art for my National Geographic piece about ice ages, as well as the cover. If today's announcement does talk about open water in Meridiani, here's Kees's view of it.

And as a Mac user, I can't say for sure how good the Mars globe software you can download from Geofusion is, but when Chuck Stein demo'd the full-up version it was stunning (this too has a National Geographic link -- it was developed for a display in the society's Hall of Explorers).

Update: Rupert Goodwins, who knows about such things, says in the comments that the Geofusion Mars download is very good indeed, if you have the right graphiocs cards and a lot of memory

Comments

[Charles Schmidt]

Gentlemen,
My training is in linguistics and Russian Lit., but I have followed Mars closely since '98. Thank you Oliver for writing "Mapping Mars";it is unquestionably the finest work on Mars for the layperson. Some chapters I reread slowly with relish. And thank you Bruce for your outstanding reporting.
Observing Kees's wet Terra Meridiani, his sea level leaves a dry zone at the landing ellipse. The image got me thinking about water depth. If there was indeed some depth of water at Terra Meridiani, I'm curious how that might relate to contemporaneous water levels globally, for while Meridiani may be very very flat, it's not exactly below datum either. See MOLA link

http://ltpwww.gsfc.nasa.gov/tharsis/Mars_topography_from_MOLA/M_-10_0_-10_0.html

Who's to say if the standing liquid water was global or not. My thinking is that liquid water at such an elevation may speak to rather large volumes of water elsewhere - such as the "basin" to the north - given the need to inundate Meridiani which is about at datum (MOLA middle green). It seems likely that today's press conference will speak to this....

Thanks again for a great blog, and forgive my naive questions.

[Oliver Morton]

Thanks for the kind words. The point about "sea level" is very interesting. It's possible that Meridiani underwent regional uplift after the rocks were laid down; there was a geophysics paper a while back, by Roger Phillips and lots of MOLA people, which argued the creation of Tharsis would have warped the whole lithosphere, causing a trough all around Tharsis (think Chryse) and a compensating uplift on the other side of the trough (pdf at http://ltpwww.gsfc.nasa.gov/tharsis/phillips.tharsis.pdf ). Meridiani would be a little further west than you'd imagine such uplift being felt, but I'd guess that it's a possibility. In that case Meridiani might have started off a fair bit lower; it might be an uplifted version of the sort of terrain now hidden under the Northern plains.

Or there may just have been lots and lots of water...

[Rupert Goodwins]

An unreconstructed Windows user writes: the Mars globe software from Geofusion is more than worth the download. You do need a spiffy graphics card and half a gig of memory to do it justice - it flys on my 2GHz P4 at home, which has both those things, but judders in a most un-celestial fashion on my 2.4GHz P4 at work, which has neither.

R

[Rupert Goodwins]

More on the Geofusion globe: my friend, the excellently named Adrian Mars, reports that a higher resolution version will be available soon for around $30. He also seems to have got himself lined up for an early version of same: armchair rovers, rejoice.

R

[Charles Schmidt]

The Geofusion globe has got my interest, though it's not clear to me if it would run on my newish Dell Dimension. I've been aiming to buy a globe to improve my knowledge of the true projection and continuity of Mars' Terrae. You can't beat a physical sphere, although a low cost software version runs a close second. Thanks for the tip Rupert.

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