Mars southern polar region covered with ice: scientists

http://english.people.com.cn/200703/16/eng20070316_358259.html(By. Lily)

Scientists have discovered that the southern polar region of Mars contains enough ice to cover the planet in a layer of water 36 feet (11 meters) deep.
Scientists at the Jet Propulsion Laboratory (JPL) in Pasadena, California, announced that an instrument on the European Space Agency's Mars Express determined that the ice on the south pole goes at least 2.3 miles (3.7 km) below the surface.
The discovery was the result of joint efforts by the Italian Space Agency and researchers at the JPL, which is part of the U.S. National Aeronautics and Space Administration (NASA). The team has been working to determine the thickness of the frozen water on Mars.
The study's findings are published in Thursday's online edition of "Science."
"The south pole's layered deposits of Mars cover an area bigger than Texas. The amount of water they contain has been estimated before, but never with the level of confidence this radar makes possible," said Jeffrey Plaut of JPL in Pasandena, near Los Angeles.
Scientists are using the Mars Advanced Radar for Subsurface and Ionospheric Sounding, otherwise known as MARSIS, to also map the thickness of similar deposits on the north pole of Mars.
"MARSIS is showing itself to be a very powerful tool to probe underneath the Martian surface, and it's showing how our team's goals, such as probing the polar layered deposits, are being successfully achieved," said Giovanni Picardi, principal investigator of the project.
"Not only is MARSIS providing us with the first-ever views of Mars' subsurface at those depths, but the details we are seeing are truly amazing."
The polar layered deposits hold most of the known water on Mars, although other areas of the planet appear to have been very wet at other times, according to the researchers.
Discovering the history of water on Mars is key to determining whether the planet ever supported life.
The frozen water deposits are also helping researchers learn more about the internal structures of Mars.
"We didn't really know where the bottom of the deposit was," Plaut said. "Now we can see that the crust has not been depressed by the weight of the ice as it would be on Earth. The crust and upper mantle of Mars are stiffer than the Earth's, probably because the interior of Mars is so much colder."