spacetoday.net: Spacecraft sees geologic changes on Mars

Posted: Wed, Sep 21, 2005, 8:34 AM ET (1234 GMT)
MGS image of Mars gullies (NASA/JPL/MSSS/ASU)

New images from NASA's Mars Global Surveyor (MGS) spacecraft have revealed features on Mars that did not exist just a few years earlier, a sign the planet is undergoing geological and climatological changes. By comparing images taken by MGS since it entered Mars orbit in 1997, scientists said they have seen a number of changes on the surface of the planet, such as gullies in a sand dune that did not exist three years ago. MGS images have also shown that carbon dioxide ice deposits near the Martian south pole have gotten smaller in each of the last three Martian years, a sign that the planet may be warming. Other observations, though, indicate that the cratering rate on the planet may be only one-fifth as high as previously expected, which could influence estimates of the age of particular regions of the planet based on counting craters.