Viking 2 Likely Came Close to Finding H2O

Sept. 28, 2009 -- NASA's Viking probes landed on Mars in 1976 to look for water and signs of life. Finding neither, Mars was abandoned for the next two decades.

But if Viking 2, which touched down in an equatorial region known as Utopia Planitia, had just dug down into the soil a few more inches, scientists now think it would have hit nearly pure frozen water.

"Oh my, oh my," said retired Viking scientist Patricia Straat.

"A lot of people think there isn't life on Mars because there wasn't any water on Mars. Our experiment was a definite positive response for life, but a lot of people have claimed that it was a false positive for a variety of reasons. One of the reasons was because there wasn't any water found," Straat told Discovery News.

Scientists announced last week that NASA's sharp-eyed Mars Reconnaissance Orbiter found ice in five freshly made impact craters, several very close to Viking 2's landing site. The sampling leads scientists to believe that a widespread layer of ice is buried about 10 inches beneath the planet's surface.

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"Every indication is that this is forming a broad, continuous sheet underneath the surface. We have five separate impact sites all showing more or less the same thing," said MRO scientist Shane Byrne, with the University of Arizona in Tucson.

"It means that Mars had a more humid atmosphere in the recent past, perhaps 10,000 years or so ago," he added.

The ice sheet is believed to extend from the north pole to about halfway to the equator, a lower latitude than scientists expected given Mars' climate.

Scientists estimate that it is about a yard or so thick. MRO has not yet been able to find ice in the southern latitudes, though scientists suspect an ice sheet exists there as well.

"The kind of scientifically heart-breaking aspect of this work is that these craters are located very close to the Viking 2 landing site, (which) dug a trench about 4- to 6 inches deep," said Selby Cull, an MRO science team member at Washington University in St. Louis.

"If Viking 2 had just been able to dig down a few more inches it would have hit ice," she said. "We would have liked to have had that information about Mars for the last 30 years. I don't know how that would have changed our perspective, but it certainly would have."

Related Links:

NASA: The Viking Mission