[meteorite-list] Simulations Show Liquid Water Could Exist on Mars

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed Nov 9 12:26:18 2005
Message-ID: <200511091724.jA9HOr100621_at_zagami.jpl.nasa.gov>

http://dailyheadlines.uark.edu/5717.htm

FOR RELEASE: Monday, November 07, 2005

Simulations Show Liquid Water Could Exist on Mars
Derek Sears
University of Arkansas

FAYETTEVILLE, Ark. - University of Arkansas researchers have become the
first scientists to show that liquid water could exist for considerable
times on the surface of Mars.

Julie Chittenden, a graduate student with the Arkansas Center for Space
and Planetary Sciences, and Derek Sears, director of the Space Center
and the W.M. Keck Professor of Planetary Sciences, will report their
findings in an upcoming issue of the Geophysical Research Letters.

"These experiments will help us understand how water behaves on Mars,"
Chittenden said.

Researchers have debated whether or not liquid water could exist on the
surface of Mars because of the low temperatures and pressures found on
the planet. Based on previous experiments and hypotheses, scientists
have speculated that pure water on the planet's surface would evaporate
from solid to gas, bypassing the liquid phase, at the low pressures
found on Mars - 7 millibars as opposed to about 1,013 millibars on
Earth. However, the planet's surface sports features like gullies and
channels that look as though they might have been created by the
movement of liquid. Terrestrial experiments designed to simulate
Mars-like conditions have been performed to help answer this question of
whether or not liquid water exists on Mars, but until this point they
have only been done with pure water at high pressures.

Chittenden and Sears used a planetary environmental chamber in the W.M.
Keck Laboratory for Space Simulation to simulate the conditions found on
Mars - an atmosphere of carbon dioxide, 7 millibars of pressure and
temperatures from zero degrees Celsius to 25 degrees below - and
examined the evaporation rates of brine solutions expected to be found
on Mars. Most water on Earth contains salts that leech into the water
when it comes in contact with soil, and similar processes might be
expected to occur in any surface water found on the Red Planet. Salts in
the water lower the freezing point of the solution.

The University of Arkansas team placed the salt solutions in the
planetary environmental chamber simulating Mars-like conditions, and
then measured the evaporation rates at varying temperatures.

"There's a huge decrease in the evaporation rate the colder it gets,
more than anyone realized," Chittenden said. With the dissolved sodium
and calcium in the water, the freezing point for the brine mixtures
drops to 21 degrees below zero Celsius for salt water and 50 degrees
below zero for water containing calcium chloride.

Temperatures on Mars vary between 125 degrees below zero Celsius and 28
degrees above at different latitudes and different times of the day.
Thus, there is a possibility that liquid water could exist on the
planet's surface at different locations and times of day.

"Brine formation could considerably increase the stability of water on
Mars by both extending the temperature range over which liquid water is
stable to negative-40 degrees Celsius and by decreasing the evaporation
rates by two orders of magnitude," the researchers wrote.

###

Contact:

Derek Sears, director
Arkansas Center for Space and Planetary Sciences
W.M. Keck Professor of Space and Planetary Sciences
(479) 575-7625, dsears_at_uark.edu

Julie Chittenden, graduate student
Arkansas Center for Space and Planetary Sciences
(479) 575-3170, jchitte_at_uark.edu

Melissa Lutz Blouin, managing editor, science and research communications
University Relations
(479) 575-5555, blouin_at_uark.edu
Received on Wed 09 Nov 2005 12:24:52 PM PST