The interplay of bright and dark material at the rim of Marcia crater on Vesta is visible in this image mosaic taken by NASA's Dawn spacecraft. The brightness variation at Vesta is now known to be among the most extreme of the rocky bodies in the solar system. Scientists believe the bright material is uncontaminated by dark material and is native to Vesta. They now believe the dark material was brought to Vesta when carbon-rich space rocks collided with its surface. Earlier ideas about the dark material included theories that it came from Vesta's underlying geology, or came from ancient volcanic flows or intrusions exposed by the Marcia impact.
This images that make up the mosaic were obtained by Dawn's framing camera on Dec. 21, 2011, and Jan. 5, 2012, during the mission's low-altitude mapping orbit (on average 130 miles or 210 kilometers above the surface). This image covers about 100 square miles (250 square kilometers). Marcia crater is in Vesta's northern hemisphere.
The Dawn mission to the asteroids Vesta and Ceres is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, for NASA's Science Mission Directorate, Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Ala. UCLA is responsible for overall Dawn mission science. The Dawn Framing Cameras have been 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 the Dawn mission is online at http://www.nasa.gov/dawn and http://dawn.jpl.nasa.gov.