This detail of a Dawn FC (framing camera) image shows many fresh craters, several with bright ejecta rays, which were formed by impacts into the floor of Vesta's south polar basin. The three most distinctive rayed craters are in the top and middle of the image and each has a clear raised crater rim. Ejecta rays form when material is thrown out of a crater during an impact. These ejecta rays most commonly have a higher albedo (are brighter) than the surrounding surface, as is the case here. Sometimes larger masses of ejecta form small secondary craters near these ejecta rays. Even though this image resolves numerous small craters, only a few hundred meters across, higher resolution imagery is necessary to identify secondary craters in this case. The rayed craters also contain enigmatic low albedo dark material, which is seen across Vesta. The distinctive hummocky (e.g. wavy/undulating) terrane of Vesta's south polar region is evident throughout this image as well.
NASA's Dawn spacecraft obtained this image with its framing camera on September 9th 2011. This image was taken through the camera's clear filter. The distance to the surface is 1390km and the image resolution is about 130 meters per pixel.
The Dawn mission to Vesta and Ceres is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, Calif., for NASA's Science Mission Directorate, Washington. UCLA is responsible for overall Dawn mission science. The Dawn framing cameras were developed and built under the leadership of the Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany, with significant contributions by DLR German Aerospace Center, Institute of Planetary Research, Berlin, and in coordination with the Institute of Computer and Communication Network Engineering, Braunschweig. The Framing Camera project is funded by the Max Planck Society, DLR, and NASA/JPL.
More information about Dawn is online at http://www.nasa.gov/dawn and http://dawn.jpl.nasa.gov.