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Posted by rgregoryclark on October 30, 2006, 8:02 am
Please log in for more thread options Over billions or even tens of millions we would would expect much of
the water lain minerals and sediments to be buried. This would effect
the conclusions about how long water was present on the surface.
Members of the OMEGA infrared spectrometer team on Mars Express have
argued water existed on the surface for a geologically short time
because of the spotty presence of clays they have detected.
However, members of the MARSIS radar team on Mars Express found large
amounts of buried water or ice on Mars. It is unknown if or how long
this could have been at the surface before being buried.
Mars Express and the story of water on Mars
16 October 2006
http://www.esa.int/SPECIALS/Mars_Express/SEMADOV74TE_0.html
Bob Clark
baalke@earthlink.net wrote:
> http://www.vtnews.vt.edu/story.php?relyear=2006&itemno=568
>
> Was there water on Mars long enough for the origination of life?
> By Susan Trulove
> Virginia Polytechnic Institute and State University
> October 19, 2006
>
> BLACKSBURG, VA. -- Based on the lovely green rock,
> olivine, also known as the gemstone, peridot, a Virginia Tech graduate
> student has created a mineral lifetime diagram that provides the a clue
> to when and for how long there might have been water on Mars.
>
> Amanda Albright Olsen of Altoona, Pa., a doctoral student in
> geosciences
> at Virginia Tech, will present the research at the Geological Society
> of
> America national meeting in Philadelphia on Oct. 22-25. Virginia Tech
> Geosciences Professor Donald Rimstidt of Christiansburg, Va., is
> co-author.
>
> Olivine, a silicate mineral rich in magnesium and iron, is found on
> earth in volcanic rock (basalts). It has also been spotted on Mars -
> most recently and in significant amounts by NASA's Mars Odyssey
> spacecraft (Geology, June 2005). Because life requires liquid water and
> because olivine dissolves in water, Olsen set out to establish how long
> it takes olivine to dissolve. The answer could help scientists
> determine
> if there was liquid water on Mars long enough for life to develop.
>
> "Our goal is to produce a robust analysis of olivine dissolution that
> can be used to predict olivine grain lifetimes," Olsen said.
>
> She used published information and laboratory studies to construct a
> baseline model, and introduced controlling factors, such as pH and
> temperature. Since environmental factors have often resulted in slower
> dissolution rates in the field than in the lab, she compared her
> results
> with an analysis of olivine in natural environments by Virginia Tech
> Geoscience Professor Michal Kowalewski and Rimstidt (2003), who
> determined average mineral grain lifetimes based on radiometric dates.
>
> Olsen and Rimstidt's conclusion is that the Martian olivine could take
> between slightly less than a million years to as long as many millions
> of years to dissolve in water. She cautions that pH is a highly
> controlling factor and a more precise estimate awaits information on
> the
> chemical conditions on the Mars surface.
>
> "Amanda's research will be a tool to help others pin it down," Rimstidt
> said.
>
> "Regardless of what physiochemical conditions that we postulate for
> early Martian history, we can now propose a scenario and ask, 'Is it
> reasonable to expect that life could have originated in this time
> frame?'" Olsen said.
>
> Olsen will present the paper, "Using mineral lifetime diagrams:
> Predicting olivine grain lifetimes on Earth and Mars," at 10:30 a.m.
> Wednesday, Oct. 25, in Pennsylvania Convention Center room 111 AB.
>
> Contact for more information
>
> Amanda Olsen, amalbrig@vt.edu or 540-231-1992
>
> http://www.geos.vt.edu/people/amalbrig/
>
> Dr. J. Donald Rimstidt, Professor of Geochemistry, jdr02@vt.edu or
> 540-231-6589
>
> http://www.geos.vt.edu/people/jdr02/
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