dipper@utastro.UUCP (Debbie Byrd) (11/30/85)
The desert planet Mars may really have plenty of water. More -- after this. November 30 Water on Mars Mars -- a frozen desert world -- probably has lots of water in various forms of ice. There may even be liquid water in some places on Mars -- as little as half a mile beneath the ground. Water on Mars was the topic of a workshop held last winter at NASA Ames Research Center in California. The 83 scientists attending discussed the fact that the martian poles once tilted more directly toward the sun than they do now. At that time, early in the history of Mars, more of the polar ice caps would have evaporated during the continual day of the martian polar summer. Winds on Mars would have carried this vapor from the poles toward the equator -- where the chill of night on this cold world may have transformed the vapor into snow. Or, given a warmer climate, rain may have fallen on Mars. There are features on Mars that look like dry river beds. There's also evidence that ice-covered lakes once dotted the surface of Mars. In a vast system of canyons called Valles Marineris, layers of sediments appear to have been laid down in liquid water. Torrential flows of water -- apparently needed to carve some of the great valleys -- remain mysterious. They may have come from the sudden release of dammed-up lakes, or from volcanic eruptions of large amounts of subsurface water. Today Mars is very cold, so that liquid water on the surface freezes. But there's ice at the poles and in upper layers of the ground -- and reason to suspect that in many places there may be liquid water below the ice. Script by Deborah Byrd. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin