Dry ice find hints Mars was a wetter place: study

This 27 August, 2003 NASAs Hubble Space Telescope portrait of Mars was snapped within minutes of the planets closest approach to Earth in nearly 60,000 years. NASA has discovered that the south pole of Mars is home to 30 times more dry ice than previously believed, suggesting that the red planet was once a much wetter place. (AFP/File/Nasa)

April 25, 2011
WASHINGTON (AFP) - NASA has discovered that the south pole of Mars is home to 30 times more dry ice than previously believed, suggesting that the red planet was once a much wetter place, said a study on Thursday.

Taking data from the Mars Reconnaissance Orbiter, researchers found "large quantities of ancient atmospheric carbon dioxide may be trapped in the solid chunks of dry ice," said the study published in the journal Science.

"The results add to a growing pile of evidence suggesting that long ago, ancient Mars had a thicker, carbon dioxide-filled atmosphere and flowing bodies of water," said the study.

The dry ice reservoir is nearly 3,000 cubic miles, similar in volume to Lake Superior, the largest of the Five Great Lakes of North America, NASA said in a statement.

The red planet's atmosphere is about 95 percent carbon dioxide, compared to Earth's which is about .04 percent carbon dioxide.

"We already knew there is a small perennial cap of carbon-dioxide ice on top of the water ice there, but this buried deposit has about 30 times more dry ice than previously estimated," said lead author Roger Phillips of the Southwest Research Institute in Boulder, Colorado.