Frost on Mars

Frost on Mars

Fig. 8.6 . Atmospheric water vapor freezes onto the surface of Mars, producing a very thin coating of water ice on rocks and soil photographed from the Viking 2 lander at its Utopia Planitia landing site on 18 May 1979. Scientists believe dust particles in the atmosphere pick up bits of solid water; carbon dioxide, which makes up 95 percent of the Martian atmosphere, freezes and adheres to the particles and they become heavy enough to sink. Warmed by the Sun, the surface evaporates the carbon dioxide and returns it to the atmosphere leaving behind the water and dust in the white patches of frost shown here. The frost remained on the surface for about 100 Earth days. (Courtesy of NASA/JPL.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University