Tuesday, December 22, 2009

NASA Scientists Find Evidence for Liquid Water on a Frozen Early Mars

Evidence suggests flowing water formed the rivers and gullies on the Mars surface, even though surface temperatures were below freezing
NASA scientists modeled freezing conditions on Mars to test whether liquid water could have been present to form the surface features of the Martian landscape.

Researchers report that fluids loaded with dissolved minerals containing elements such as silicon, iron, magnesium, potassium and aluminum, can remain in a liquid state at temperatures well below freezing. The results of this research appear in the May 21 issue of Nature magazine entitled "Stability Against Freezing of Aqueous Solutions on Early Mars."

"We found that the salts in water solutions can reduce the melting point of water, which may help explain how liquid water existed in a frozen Martian environment," said Alberto Fairén, a space scientist at NASA Ames Research Center, Moffett Field, Calif. and the lead author of the study.

To understand what formed the surface features on Mars, scientists have focused on the early Martian conditions. Was early Mars warm and wet, or cold and dry? Surface features throughout most of the Martian landscape suggest the presence of water ponds ranging from seas to lakes, and rivers and gullies formed by flowing water, which imply that early Mars was wet.

But there also is some evidence that suggests that Mars may have been permanently cold, with global temperatures well below the freezing point of pure water. To study the 'liquidity' of water on Mars, climate modelers first simulated various concentrations of greenhouse gases in its atmosphere. They found that these gases cannot efficiently raise the surface temperature above freezing.

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