Mars Global Surveyor Shows Active Red Planet
New images of the surface of Mars reveal more activity on the neighboring planet than previously thought. In an image from April 2005, researchers were able to identify gullies in a sand dune for the first time that had not existed there in 2002. Such tracks could form when frozen carbon dioxide, buried under a layer of dust in winter, evaporates in spring, setting the sand in motion. Similar effects are known to geoscientists from active sand dunes in Antarctica.
Another image shows that the carbon dioxide ice sheets at the planet's south pole have steadily decreased for three consecutive summers. The ice cap there, which also exists in summer, is characterized by complex structures with plateaus, ditches and round depressions. The scientists found that some slopes had retreated by up to three meters per Martian year. Also, new plains had formed and entire mountains had disappeared.
Apparently, the researchers conclude, carbon dioxide escapes into the atmosphere there without being replaced. This suggests, for example, a warm climate phase on the red planet. It is possible that conditions on the neighbors would have been much frostier a short time ago.
The multiple pole crossing was actually planned in order to get several images of the same region that were slightly offset from each other and to create stereo images with a 3-D impression from them. To the great surprise of the researchers, this was not possible: the ice cover within just two Earth years - a good Martian year - was already too different.
Mars Global Surveyor was launched on November 7, 1996 and entered Mars orbit in September 1997.