Martian Gully Surprise
Image Title: Martian Gully Surprise
Source: Mars Global Surveyor
Mars has always been able to surprise us. One of the biggest surprises was revealed by the Mars Global Surveyor mission. Numerous images of crater and valley walls showed the presence of gullies. On Earth, features like this are caused by erosion due to the presence of liquid water. This has presented planetary scientists with something of a problem since our understanding of Mars would seem to prohibit such erosion.
Seen above is my interpretation of one of these Mars Global Surveyor images, which was taken using the Narrow Angle camera in September 1999. This same MGS image was used for the cover of the June 30, 2000 issue of Science magazine in which the article "Evidence for Recent Groundwater Seepage and Surface Runoff on Mars" by Michael Malin and Kenneth Edgett appeared.
The feature shown in the image is located in the upper wall of an impact crater that is in the region of Mars known as Noachis Terra. It is located at approximately 55° south latitude and 342° west longitude. The feature has three components. From top to bottom they are an alcove, a gully and a debris apron. The alcove is formed above the area where the water seeps out of the rock. It is created as seepage removes the material that supported the overlying rocks. With it's support removed, the material collapses and is transported down slope. The channels are the paths taken by the debris flow. They are created by the erosion caused by the down slope transport of the debris from above. The debris aprons is where the materials eroded from above come to rest after traveling down the channel.
Source Image Background
The source image is a Mars Global Surveyor Narrow Angle Camera view taken in September 1999. The official NASA version of this image, along with additional background information, is at PIA01035: Evidence for Recent Liquid Water on Mars: Gullies in Crater Wall, Noachis Terra.
All processing of this false color image was done using Adobe Photoshop.
I have created a low resolution version of Martian Gully Surprise for use as a desktop wallpaper. I am making this wallpaper available for your personal use only. It is not to be modified or redistributed in any form by any means. All rights are retained by the artist.