Telling a salty tale of martian water (Forwarded)
From: Andrew Yee (ayee_at_nova.astro.utoronto.ca)
Date: 10/08/04
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Date: Fri, 08 Oct 2004 09:54:14 -0400
News and Public Affairs Office
Los Alamos National Laboratory
Contact:
Todd Hanson, tahanson@lanl.gov, (505) 665-2085
Oct. 7, 2004
04-080
Telling a salty tale of martian water
LOS ALAMOS, N.M. -- University of California scientists working at Los Alamos
National Laboratory, along with a scientist from Indiana University have devised
a method for determining whether sulfate salts can account for evidence of water
on Mars. The work could pave the way to a better understanding of the martian
environment and the history of water on Mars.
In a paper published in today's issue of the scientific journal Nature, a team
of researchers lead by Los Alamos scientist David Vaniman describe the exposure
of magnesium sulfate salts to various temperature, pressure and humidity
conditions in order to understand their possible hydration states under martian
surface conditions. The researchers discovered that the crystalline structure
and water content of the salts are dependent on time-humidity history and that
magnesium sulfate salts could retain sufficient water to explain at least a
portion of the NASA Odyssey observations, which revealed surprisingly high
abundances of near-surface hydrogen.
According to Vaniman, "It's important to recognize that despite several unmanned
missions to explore the geology of Mars, we still know relatively little about
the martian environment and especially the history of water on Mars. This work
is characteristic of the kind of knowledge base we need to create before humans
ever travel to Mars, so that we can understand the martian world once we get there."
The experiments examined the formation and transformation of magnesium sulfate
minerals precipitated by evaporation from solutions and exposed in the solid
state to controlled temperature and humidity conditions. The experiments
included conditions that were slightly less than Mars atmospheric pressure, as
well as other experiments conducted at temperatures from minus 280 degrees
Fahrenheit to 77 degrees Fahrenheit and pressures from less than 1/1000 of
Earth's atmosphere to ambient pressure.
The researchers used thermogravimetric analysis (TGA) and isothermal
controlled-humidity gravimetric analysis to examine water gain and loss from the
samples. They also collected extensive data from X-Ray Diffraction (XRD)
analyses collected while samples were held in an environmental cell at
controlled relative humidity and ambient temperature of 77 degrees Fahrenheit
inside the diffractometer.
The experiments suggest that studies of martian salts can provide vital
information about the hydrogeologic history of Mars and reveal that the return
of samples to Earth for detailed study should be an important planetary science
research goal. However, the results also show that because of the ease with
which dehydration/rehydration transformations take place in the magnesium
sulfate salts, the mineralogy might be more accurately characterized in situ
before samples are removed from the Mars surface. The research, coupled with
previous experience with extra-planetary samples, demonstrates that these and
any other environmentally sensitive salts collected on Mars will likely not be
returned to Earth in an unmodified state unless exceptional effort is made to
preserve martian environmental conditions during sample return.
In addition to Vaniman, the research team included Steve Chipera, Claire
Fialips, J. William Carey and William Feldman, all of Los Alamos, as well as
former Los Alamos scientist David Bish, now at Indiana University.
The research was supported by a NASA Mars Fundamental Research Program Grant and
through a Los Alamos Laboratory-Directed Research and Development (LDRD)
project, headed by Los Alamos scientist Herbert Funsten, to expand knowledge of
water on Mars. LDRD funds basic and applied research and development focusing on
creative concepts selected at the discretion of the Laboratory Director.
Los Alamos National Laboratory is operated by the University of California for
the National Nuclear Security Administration (NNSA) of the U.S. Department of
Energy and works in partnership with NNSA's Sandia and Lawrence Livermore
national laboratories to support NNSA in its mission.
Los Alamos enhances global security by ensuring the safety and reliability of
the U.S. nuclear deterrent, developing technologies to reduce threats from
weapons of mass destruction, and solving problems related to defense, energy,
environment, infrastructure, health and national security concerns.
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