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Green Mineral Indicates Mars Is Dry
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Green Mineral Indicates Mars Is Dry
(Gordon D. Pusch) wrote in message ...
(Ron Baalke) writes: Green mineral indicates red planet is dry The presence of a common green mineral on Mars suggests that the red planet could have been cold and dry since the mineral has been exposed, which may be more than a billion years according to new research appearing in the Oct. 24 edition of Science. [...] The fact that so much olivine is exposed at the surface indicates that there has been little to no weathering due to water, thus no liquid water-mineral chemical reactions. The age of the surface is somewhat uncertain but is probably over 3 billion years old. It should be noted that Nili Fossae is a Martian "highland" region, and is further above the martian "lowlands" than Mt. Everest is above terrestrial sea level. ahhh - no. Nili Fossa is at about mean planetary radius - the floor of the main valley is at about the same elevation as the MER landing sites. It is right on the edge of Isidis after all - the Beagle's target site. Christansen also reported olivine deep in the guts of Vallis Marineris in March. It is a real problem - abundant evidence for H2O as ice, and shaping the surface, but the weathering data goes right against liquid water. The carbonate data seems pretty damning as well. Maybe you are thinking of Tharsis. Hence, and notwithstanding the slower decrease in atmospheric density with altitude caused by the larger "scale height" of the Martian atmosphere, even during a "warm wet phase," one would =NOT= expect to find liquid water in the Martian "highlands," due to their higher relative altitude and Mars's lower mean temperature. Even if the "lowalnd" pressure were a substantial fraction of a bar, the Martian highland "climate" would still be a very cold, very dry, near-vacuum. Therefore, IMO, this observation says NOTHING AT ALL about the ancient martian lowland climate. The top of the south polar cap is +4 km higher than Nili Fossa. Ice does not flow uphill. (And the latest thinking is that most of the SPC is indeed water, not CO2 as previously thought). We have a real paradox here. And this result *is* important regarding water. Cheers, Duncan -- Gordon D. Pusch perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;' |
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