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Abundant ice makes case for life on Mars

Posted on: Thursday, 3 July 2003, 06:00 CDT

Ice abounds inches below Mars' north pole to such a degree that scientists now believe missions to the Red Planet could uncover evidence of past and possibly present life.

"If you have freezing and thawing cycles, if there is any type of organics, we'll be able to follow the water to look for those organics," said Chris Shinohara, a University of Arizona researcher and the project manager of the Gamma Ray Spectrometer aboard NASA's Mars Odyssey spacecraft.

Odyssey found evidence of subsurface ice on Mars last year, but the data streaming in from the planet's north pole is "knocking us over," said Will-iam Boynton, a UA cosmochemist and the principal investigator for the three instruments that make up Odyssey's Gamma Ray Spectrometer.

The water ice found as shallow as 4 inches beneath soil at the north pole is about one and a half times more than detected on the south pole, Boynton said.

"What this really means is, we almost certainly had something of the equivalent of snow falling at some time in the past to make glaciers on Mars," Boynton said. "The basis for saying that is that the ratio of ice to dirt is a lot greater than you could accommodate just by having water fill up the pore spaces in a normal, loosely packed soil."

Boynton's spectrometer detects the hydrogen in H2O and about 20 other elements.

"We were expecting to spend more time looking at the normal rock- forming minerals like iron, silicon and potassium," he said. "We never thought the hydrogen signal indicating water would be this extensive."

The results from the craft orbiting Mars could bode well for a proposal for a 2008 Mars mission submitted by the UA's Lunar and Planetary Laboratory. NASA has whittled the proposals down to the UA's, one from Arizona State University, and those of two other NASA groups.

The UA's "Phoenix" proposal incorporates instruments already built for missions that either failed or were canceled by NASA, and would drop a lander near the north pole that would dig down into the Martian soil, pull out a sample, heat it in an oven and analyze it.

"If Phoenix is selected, we'll use the results of Odyssey to really target locations for landing sites," Shinohara said. "That's where you would find what we believe is the biological potential for life."

Shinohara said NASA will make its final selection for the 2008 mission in early August.

Contact reporter Thomas Stauffer at 573-4197 or at stauffer@azstarnet.com.

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