Scientists Now Agree: There`s Water On Mars

October 9, 1985|United Press International

MOUNTAIN VIEW, CALIF. — Evidence that water exists on Mars now seems conclusive, scientists said Tuesday at a symposium sponsored by the National Aeronautics and Space Agency.

Although scientists in the past have theorized about water on the planet, there always was doubt.

The question is important because Mars, 50 million miles away, is probably the solar system`s best candidate for human exploration or colonization. Venus, for example, is too hot, and the waterless moon doesn`t have much gravity.

At the Water on Mars Workshop, about 80 specialists reported on continuing studies of data gathered by orbiters.

They depicted the planet as so cold that water would remain frozen except perhaps briefly on mid-summer days at the equator. Although the Martian atmosphere of 95 percent carbon dioxide absorbs infrared rays, the atmosphere is too thin to effectively retain heat.

It is under the polar caps of solid carbon dioxide, dry ice, that water ice is revealed when some of the carbon dioxide vaporizes each summer.

``Terrain softening`` -- the rounding off of certain geological features -- indicates water activity beneath the surface. That water is believed to lie a half-mile deep where it would be kept liquid by the planet`s internal heat.

This has not always been the situation. The climate of Mars, like Earth`s, is cyclical because of variations in its tilt toward the Sun.

Long ago Mars had a much thicker atmosphere better able to hold the Sun`s heat. A thick layer of snow would have covered the equator, and beneath the snow there would have been liquid water that carved the extensive winding channels, or dry riverbeds, photographed in 1972 by Mariner 9.

What changed the situation was the planet`s cooling. With less lava coming up to the surface, more carbon dioxide changed into carbonate rock, depleting the atmosphere. As a result the atmosphere steadily lost ability to hold heat.

Key reports were given the workshop by Peter Schulz of Brown University, Bruce Janofsky of the University of Colorado, Gary Clow and Michael Carr of the U.S. Geological Survey, and Steven Squyres, Robert Haberle and James Pollack, all of NASA.

They said understanding past and present climate changes on Mars will help scientists find a better understanding of changes in the weather on Earth.

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