Carbon Dioxide Snow, Key to Life on Mars?; COSMOLOGY: Global Surveyor Observations
Byline: JOHN VON RADOWITZ
STUDIES of Martian snow suggest that the planet has a changing climate which could allow liquid water to exist temporarily on its surface, it has been disclosed.
If scientists confirm this is happening it would have major implications for the chances of finding primitive life surviving on Mars.
Snow at the Martian poles is composed of frozen carbon dioxide (CO 2), not water ice as on Earth.
Observations by the Mars Global Surveyor spacecraft now orbiting the planet indicate that Martian snow is much more dense than its Earthly counterpart.
In the journal Science, two teams of researchers report findings from Global Surveyor data which shed new light on the Martian climate.
Images of pits and other features at the Martian south pole confirmed the presence of a year-round reservoir of solid CO 2on the planet's surface.
The features appeared to have shrunk one to three metres over the course of a Martian year, due to evaporation of the carbon dioxide ice.
The second study measured the depth of snow deposits at the planet's polar caps.
In one year, Mars exchanged up to a third of the CO 2in its atmosphere, resulting in cycles of snow accumulation and evaporation at the poles and lower latitudes during winter and summer.
The size of the CO 2reservoir, which is still unknown, could affect phenomena like the presence of surface liquid water. …