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ASU finding suggests Mars may support life
By William Hermann The Arizona Republic Feb. 20, 2003
An ASU scientist believes he has found conditions on Mars that would support life.
The findings, announced by Arizona State University planetary geologist Phil Christensen at a NASA news conference Wednesday in Washington, D.C., could also provide a map for future exploration of the planet.
He said he has found snow deposits and evidence of flowing water beneath them, which he believes is a logical explanation for the gullies and ravines where the snow is found. Scientists have known for years that ice exists on Mars but had believed any water from the ice would evaporate.
"These snow deposits with water running beneath are one of the best possible environments we could hope for to support life on Mars," ASU spokesman James Hathaway said. "The snow acts as a greenhouse; you have sufficiently low temperatures, running water and some sunlight, everything you need for life.
"On Earth, streams under glaciers are rich with life. It's microbiological life, but it's life."
Biologist Lynn Rothschild, who works at the NASA Ames Research Center in Mountain View, Calif., spoke at the news conference and said she thought Christensen's hypothesis, "has expanded the envelope of places on Mars where there could be life."
She said life may be found not only in the running water beneath the snow, but in the snow itself. She noted that algae is found in snow on Earth.
Scientists for the past few years have been looking closely at the possibility of water existing on Mars and perhaps being a medium in which life could exist.
In June 2000, NASA announced its Mars Global Surveyor probe had taken photographs showing carved gullies indicating the recent presence of moving water on Mars. The discovery suggested possible sources of water just beneath the planet's surface and increased the prospects of finding past or present life there. But scientists across the country immediately questioned whether water could exist in Mars' cold, thin, dry atmosphere.
Christensen regularly examines images evaluated at ASU from the Thermal Emission Imaging System, or THEMIS, aboard the Mars Odyssey, launched in 2001. His scrutiny has led him to make a basic connection between the Martian gullies and snow deposits he believes he has found using the imaging system. The snow remains in cold, generally shaded places in the Martian mid-latitudes, Christensen said.
"You hang around this business long enough, and sometimes you find something fun," Christensen said in a telephone interview from Washington before Wednesday's conference.
"About six months ago I saw on images from the THEMIS camera material that looked like something pasted on the cold slopes of craters facing away from the sun," he said. "I believe this material is snow. As it melts away, it reveals gullies."
Christensen said he had doubted that water was seeping to the surface from underground faults, as the June 2000 NASA report had suggested, particularly because those faults were at high elevations where such seeps likely would not exist. When he considered the gullies he was seeing, then considered the snow he was sure existed, he believed he had found something important.
"It literally felt like a light bulb going off. I thought, 'I know how these gullies form; snow has blanketed the surface of Mars and, when it melts, water trickles down through the snow and carves out these gullies."
And the snow above protects the water moving below from the atmosphere and keeps it from evaporating, Christensen said.
Jack Farmer, who heads ASU's astrobiology program, says the findings support the need for a manned mission to Mars.
"The real impact of Phil's discovery and newly emerging hypothesis is we could have fairly widespread water-rich habitats on Mars that could support life," Farmer said. "These become important targets for exploration. We probably need to go there."
Farmer said a spacecraft probably won't "go there" until 2009, when NASA has scheduled a nuclear-powered rover to land on the planet.
"It could be sent to one of the sites that become very likely sites of water and look for organic material," Farmer said.
Christensen said he has been encouraged by the reactions to his hypothesis.
"Most people I know and respect go, 'Damn, I'm embarrassed I didn't think of that,' " Christensen said. "When you see these images, you go, 'Of course.' "