The quest for water

The Idea that liquid water on mars could one day support life is one of the most intriguing concepts. Yet, the possibility that this idea might one day become a reality is highly supported by the existance of Martian Ice caps at both the north and south poles. If we could one day heat the surface temperature of mars to a point at which the ice at the caps would melt, liquid water would be present at the Martian surface, and possibly one day support living organisms.

The ice on Mars is a mixture of frozen carbon dioxide, more commonly known as dry ice, and frozen water. While there is no currently present liquid water on the surface of Mars, dried river beds and floodplains support that mars was once a planet with surface liquid. However, the current information suggests that mars cooled below freezing temperatures sometime at about 3.8 billion years ago.

"The valley networks formed more than 3.8 billion years ago. They must have been carved by rivers fed by rainfall or groundwater sapping," says Francois Costard from the Laboratoire de Giologie Dynamique de la Terre et des Planhtes, Orsay, France. "Liquid water must have been on the surface for a long time to form them, so the temperature and pressure must have been higher then than now."

Signs of water remain on the surface of Mars providing evidence that at one time Mars was a warmer place which could in fact support liquid water. The photo at left shows a crater with evidence of glacial fill. Even the carved hollow where the glacier once resided remains as a scare on the surface. Above, this photo dipictes evidence of liquid errosion which suggest flowing water once moved accross the surface.

As Mars is now, the surface temperature is too low to support liquid water and the atmosphere is too thin to support surface ice for long. This is why, though water was once present all over the surface there is no ice beyond the limits of the poles. Any ice in these places would quickly turn to water vapor under the intense radiation of the sun. With no atmosphere to provide protection to the frozen water, the ice vaporized from the surface leaving behind only the north and south poles.

This image provided by NASA's Odessey mission shows thermal and epithermal neutron images of the North (right) and south (left) poles. Enhancements of these images show that the surface ice is dry ice but that there is subsurface water ice.