Mars may have been both cold and wet
Wed May 20, 2009 1:27pm EDT
LONDON (Reuters) - Mars may have once been both cold and wet,
researchers said Wednesday, suggesting a freezing Martian landscape
could still have produced water needed to sustain life.
There has been debate over the issue because with some researchers
believing water likely formed many features of the planet's landscape
and others pointing to evidence indicating that early Mars was cold
with temperatures well below the freezing point of water.
Using a computer model, Alberto Fairen of Universidad Autonoma in
Madrid and colleagues showed that both could have been possible because
fluids containing dissolved minerals would have remained liquid at
temperatures well below 273 degrees Kelvin -- the freezing point of
pure water.
"Our results are compatible with Mars lander and orbiter data and
with climate modeling, and suggest a cold and wet early Mars," they
wrote in the journal Nature.
The presence of water on Mars is a hot topic for scientists. They
have presented strong evidence of huge deposits of frozen water at the
Martian poles and point to geological features that indicate large
bodies of water have flowed on the planet's surface in the distant past.
Other scientists have said images and computer simulations strongly
suggest a landslide of sand and gravel are more likely explanations for
the bright deposits in gullies that have been proposed as strong
evidence of water flow.
Water is a key to the question of whether life, even in the form of
microbes, ever existed on Mars. On Earth, all known forms of life
require water.
Feiren and colleagues, including scientists from NASA's Ames
Research Center in California, chose compositions based on weathered
basalts for the Martian fluids in their model to match the chemical
compositions of rock found at Mars landing sites.
This analysis showed that a number of minerals could have lowered
the melting point of water in a frozen Martian environment and help
explain the early Mars climate paradox, they said.
"The stability against freezing of Martian fluids can explain saline
water activity on the surface of Mars at mean global temperatures well
below 273 Kelvin," they wrote.
(Reporting by Michael Kahn; Editing by Maggie Fox and Jon Hemming)
© Thomson Reuters 2009. All rights reserved."/>
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