[meteorite-list] Extensive Water in Mars Interior

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 22 Jun 2012 14:02:46 -0700 (PDT)
Message-ID: <201206222102.q5ML2kRm001922_at_zagami.jpl.nasa.gov>

http://carnegiescience.edu/news/extensive_water_mar%E2%80%99s_interior

Extensive Water in Mars Interior
Carnegie Institution for Science
June 21, 2012

Washington, D.C. - Until now, Earth was the only planet known to have vast
reservoirs of water in its interior. Scientists analyzed the water
content of two Martian meteorites originating from inside the Red
Planet. They found that the amount of water in places of the Martian
mantle is vastly larger than previous estimates and is similar to that
of Earth's. The results not only affect what we know about the geologic
history of Mars, but also have implications for how water got to the
Martian surface. The data raise the possibility that Mars could have
sustained life.

The research was led by former Carnegie postdoctoral scientist Francis
McCubbin, now at the University of New Mexico. The analysis was
performed by Carnegie Institution investigator Erik Hauri and team and
is published in the journal Geology.
 
The scientists analyzed what are called shergottite meteorites. These
are fairly young meteorites that originated by partial melting of the
Martian mantle - tthe layer under the crust - and crystallized in the shallow
subsurface and on the surface. They came to Earth when ejected from Mars
approximately 2.5 million years ago. Meteorite geochemistry tells
scientists a lot about the geological processes the planet underwent.
 
"We analyzed two meteorites that had very different processing
histories," explained Hauri. "One had undergone considerable mixing with
other elements during its formation, while the other had not. We
analyzed the water content of the mineral apatite and found there was
little difference between the two even though the chemistry of trace
elements was markedly different. The results suggest that water was
incorporated during the formation of Mars and that the planet was able
to store water in its interior during the planet's differentiation."
 
Based on the mineral's water content, the scientists estimated that the
Martian mantle source from which the rocks were derived contained
between 70 and 300 parts per million (ppm) water. For comparison, the
upper mantle on Earth contains approximately 50-300 ppm water. Hauri and
team were able to determine these values with new techniques and new
standards they developed that can quantify water in apatite using a
technology called secondary ion mass spectrometry (SIMS).

"There has been substantial evidence for the presence of liquid water at
the Martian surface for some time," Hauri said. "So it's been puzzling
why previous estimates for the planet's interior have been so dry. This
new research makes sense and suggests that volcanoes may have been the
primary vehicle for getting water to the surface."
 
McCubbin concluded, "Not only does this study explain how Mars got its
water, it provides a mechanism for hydrogen storage in all the
terrestrial planets at the time of their formation."
 
This work was supported by NASA Cosmochemistry grants NNX11AG76G,
NNX10AI77G, the New Mexico Space Grant Consortium, and the Carnegie
Institution.
Received on Fri 22 Jun 2012 05:02:46 PM PDT