This image from NASA's Mars Exploration Rover Opportunity shows a portion of the heat shield that the spacecraft jettisoned shortly before landing. This flank piece broke off from the main piece of the heat shield upon impact. The crater created by the impact of the heat shield can be seen in the upper right of the image. Rover tracks appear across the top of the image. Opportunity took this image with its navigation camera during the rover's 331st martian day, or sol (Dec. 28, 2004).