From http://www.jpl.nasa.gov/galileo/

   
                        Ancient Impact Basin on Europa
                                       
   
   
   NOTE: This JPEG image is made available in order to share with the
   public the excitement of new discoveries being made via the NASA/JPL
   Galileo spacecraft. Galileo scientists are in the process of
   calibrating and validating this data. The full digital image necessary
   for scientific analysis will be released within one year of receipt of
   this orbit's last data.
   
   
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Ancient Impact Basin on Europa

   
   

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http://www.jpl.nasa.gov

PHOTO CAPTION
P-48954
July 28, 1996

   
   
   This feature on Europa was seen as a dark, diffuse circular patch on a
   previous Galileo global image of Europa's leading hemisphere on April
   3, 1997. The "bulls-eye" pattern appears to be a 140-kilometer
   (86-mile) wide impact scar (about the size of the island of Hawaii)
   which formed as the surface fractured minutes after a mountain-sized
   asteroid or comet slammed into the satellite. This approximately
   214-kilometer (132-mile) wide picture is the product of three images
   which have been processed in false color to enhance shapes and
   compositions.
   
   North is toward the top of this picture, which is illuminated from
   sunlight coming from the west. This color composite reveals a sequence
   of events which have modified the surface of Europa. The earliest
   event was the impact which formed the Tyre structure at 34 degrees
   north latitude and 146.5 degrees west longitude. The impact was
   followed by the formation of the reddish lines superposed on Tyre. The
   red color designates areas that are probably a dirty water ice
   mixture. The fine blue-green lines crossing the region from west to
   east appear to be ridges which formed after the crater.
   
   The images were taken on April 4, 1997, at a resolution of 595 meters
   (1950 feet) per picture element and a range of 703,776 kilometers
   (434,430 miles). The images were taken by Galileo's solid state
   imaging (CCD) system.
   
   The Jet Propulsion Laboratory, Pasadena, CA, manages the Galileo
   mission for NASA's Office of Space Science, Washington, DC. JPL is an
   operating division of California Institute of Technology (Caltech).
   
   This image and other images and data received from Galileo are posted
   on the World Wide Web, on the Galileo mission home page at URL
   http://www.jpl.nasa.gov/galileo. Background information and
   educational context for the images can be found at URL
   http://www.jpl.nasa.gov/galileo/sepo.