[meteorite-list] Rare Meteorites Reveal Mars Collision Caused Water Flow

[Ron Baalke]

http://www2.le.ac.uk/offices/press/press-releases/2011/february/rare-meteorites-reveal-mars-collision-caused-water-flow  

Rare meteorites reveal Mars collision caused water flow
Issued by University of Leicester Press Office
February 2, 2011

Exactly a century after the first discovery of a rare meteorite sample,
University of Leicester team uses it to reveal new insights into water
on the red planet

Rare fragments of Martian meteorites have been investigated at the
University of Leicester revealing one of the ways water flowed near the
surface of Mars. 

Scientists at the University's renowned Space Research Centre, in the
Department of Physics and Astronomy, examined five meteorite samples -
including the very first nakhlite, found a century ago.

Nakhlites are a form of meteorite known to have originated on Mars. They
are named after the village of El-Nakhla in Egypt where the first one
was found in 1911.

Findings from the research have been published in Meteoritics and
Planetary Science (Dec. 2010 issue, vol 45).  The research was funded
by the Science and Technology Facilities Council (STFC).

Hitesh Changela and Dr John Bridges  used electron microscopes in the
University's Advanced Microscopy Centre to study the structure and
composition of five nakhlites, including the 1911 specimen, which is
housed in the collections of the Natural History Museum, London. Minute
wafers of rock, about 0.1 microns thick, were milled off the meteorites
as part of the research.

By comparing the five meteorites, they showed the presence of veins
created during an impact on Mars. They suggest that this impact was
associated with a 1-10 km diameter crater. Buried ice melted during this
impact depositing clay, serpentine, carbonate and a gel deposit in the
veins. 

This work closely ties in to recent geological discoveries of clay and
carbonate on the surface of Mars made by NASA and ESA probes, and shows
how some of it probably formed.  Serpentine mineralisation is associated
with the production of methane.  It is the purpose of the 2016 Trace Gas
Orbiter mission to search for and understand the origin of any methane
in the Mars atmosphere as it can be a biomarker.  This work shows one of
the ways that methane was probably produced. 

Dr Bridges, who is supervising Hitesh's PhD, said, "We are now starting
to build a realistic model for how water deposited minerals formed on
Mars, showing that impact heating was an important process. The
constraints we are establishing about temperature, pH and duration of
the hydrothermal action help us to better understand the evolution of
the Mars surface.  This directly ties in with the current activities of
landing site selection for Mars rovers and Mars Sample Return.  With
models like this we will better understand the areas where we think that
water was once present on Mars.

_http://www2.le.ac.uk/departments/physics/research/src/research-programmes-1/planetary-science_

*ends*

*Notes to Editors:* For interviews, please contact: Dr John Bridges of
the Space Research Centre, _j.bridges at le.ac.uk_ 

*Jpeg images available from _pressoffice at le.ac.uk_