Mars Is Drier Than Expected

The surface areas of Mars are colored blue to show lots of subsurface hydrogen, indicating the presence of water.

A spacecraft orbiting Mars has discovered deposits of ice at its south pole so thick that they would cover the planet in 36 feet of water if they were melted, said scientists. The scientists used the joint NASA-Italian Space Agency radar instrument on the European Space Agency Mars Express spacecraft to estimate the thickness and volume of ice deposits at the Martian south pole. These ice deposits cover an area larger than Texas.

The deposits, up to 2.3 miles thick, are under a polar cap of white frozen carbon dioxide and water, and appear to be composed of at least 90 percent frozen water, with dust mixed in, according to findings published in the journal Science.

Scientists have known that water exists in frozen form at the Martian poles, but this research produced the most accurate measurements of just how much there is.

They are eager to learn about the history of water on Mars because water is fundamental to the question of whether the planet has ever harbored microbial or some other life. Liquid water is a necessity for life as we know it.

Characteristics like channels on the Martian surface strongly suggest the planet once was very wet, a contrast to its present arid, dusty condition.

But researchers are baffled by what happened to the water -- perhaps only 10 percent of the water that once existed on Mars is now trapped in the polar ice caps.

"Even if you took the water in these two (polar) ice caps and added it all up, it's still not nearly enough to do all of the work that we've seen that the water has done across the surface of Mars in its history."

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