Cover of Holiday Card from NASA International Affairs Division to Arthur C. Clarke, 1976. Internal caption: "A portion of the Viking I lander depicting the U.S. flag and the official symbol of the American Bicentennial is shown against a picture of the Martian surface and sky taken on July 24, 1976. Facing southeast, orange red surface materials cover most of the surface, apparently forming a thin veneer over darker bedrock. A zone of large dark boulders is present in the far field. The sky has a reddish cast, which is probably due to scattering and reflection from reddish sediment suspended in the lower atmosphere."