[X] My Assistant

[SigurRosFan]

Mars Express's OMEGA uncovers possible sites for life

- Press Release

- Press Images

[Guest_BruceMoomaw_*]

On looking again at the map of the very small patches of different hydrated minerals found on Mars by OMEGA, I still think the OMEGA team may be wrong in saying that the sulfates were caused by an actual increase in Mars' volcanic activity during the Hesperian period.

Benton Clark's view, by contrast, has been that Mars' generally stronger volcanism during its earliest days -- combined with the fact that its lack of an ozone layer allowed solar UV light to penetrate all the way to the surface -- caused sulfuric acid to form all over early Mars' surface. In its earliest Noachian days, however, there could be a lot of phyllosilicate clays produced by nonacid water simply because the planet had a lot more liquid water in general all over its surface and so the acid was highly diluted. But during the Hesperian -- at which point Mars' initial dense atmosphere had vanished -- the planet's surface had become so cold that non-acid water could no longer be liquid there, making it possible for water to be liquid on the surface only where it was mixed with a lot of H2SO4 as antifreeze.

The OMEGA map does show the small dots of phyllosilicates to be sprinkled pretty randomly all over the planet, while the sulfate deposits are concentrated entirely around the Valles Marineris and the Meriaiani drainage area at its east end -- but this distribution also fits Clark's alternative model well, since by then most of Mars' remaining volcanic activity unquestionably WAS in the Tharsis region, regardless of whether or not it was actually stronger then than Mars' volcanism had been during the Noachian.

http://www.sciencemag.org/cgi/content/full/312/5772/400 (Figure 3)

[dvandorn]

...Benton Clark's view, by contrast, has been that Mars' generally stronger volcanism during its earliest days -- combined with the fact that its lack of an ozone layer allowed solar UV light to penetrate all the way to the surface -- caused sulfuric acid to form all over early Mars' surface...

Ah, but the lack of an early Martian ozone layer is an assumption. Just as is the lack of an early Martian magnetic field. The latter seems to be on really thin ice -- I think we need to question the former assumption, as well.

-the other Doug