NASA Rover Helps Reveal Possible Secrets of Martian Life

"John Curtis" skrev i en meddelelse
oups.com...

wrote:

Scientists have been able to deduce conditions in the Meridiani Planum
region of Mars were sometimes wet, strongly acidic and oxidizing.
Those conditions probably posed stiff challenges to the origin of
Martian life.

Wet, strongly acidic and oxidizing environment results from a process
called acid mine drainage, which is strongly associated with bacteria:
http://www.mines.edu/fs_home/jhoran/ch126/microbia.htm
Acid mine drainage converts pyrite into iron (lll), sulfate,hematite,
goethite and jarosite, all found at Meridiani.

The source of pyrite is the black smoker, which is invariably
accompanied by bacteria even before the chimney is formed:
http://66.102.7.104/search?q=cache:O...ystem%22&hl=en


The article reference hydrogensulfid oozing out of the smoker, not pyrite.
Pyrite is a (biotically mediated) diagenetic product of seawater sulfates
and iron. I've never met pyrite in any rock that doesn't have a marine
progenitor, but my experience is no standard for comparison.
The article also mentions oxygen as part of the metabolic process, and I
consider that an obstacle for comparing it to martian conditions. I'm not
aware of how oxygen is released from MORB processes, and if you acknowledge
the smoker as a recirculation of initially cold oxygenated water, the oxygen
in the smoker may afterall originate from our (assumed biologically
mediated) oxygenated atmosphere. The only chemical equations on the
mine-trailing page that does not involve free oxygen reduces ferric iron to
ferrous - that the inverted result.

Carsten