Thursday, January 14, 1999 Published at 19:08 GMT
Winter wind on Mars
Mars has sand dunes just like those on Earth
By BBC News Online Science Editor Dr David Whitehouse
Images sent back to Earth by the Mars Global Surveyor (Mgs) have given scientists a glimpse into the events that take place at the north pole when vast tracts of sand dunes become covered in frost.
Although it arrived at Mars in September 1997 it was only last summer that it was able to take images of the ring of sand dunes that circle the northern polar region.
When the image was finally taken last August, some keen-eyed scientists noticed that some of the dunes had dark streaks upon them.
Because the frost is only as old as the Martian winter the wind erosion must have occurred within the past year or so.
These images, among the very best from Mgs's first year, will assist scientists to understand the strength of wind erosion on the surface.
At the moment it is springtime at the north pole of Mars. In a few weeks more powerful sunlight will fall on the frost covered dunes of dust that ring the pole and rid them of their frosty covering.
With luck the camera onboard the Mars Global Surveyor spacecraft will be watching.