The Mars Orbiter Camera (MOC) took this image on August 20, 1997, when the Mars Global Surveyor (MGS) was 5.67 million kilometers (3.52 million miles) and 22 days from entering orbit. At this distance, the MOC's resolution is about 21.2 km per picture element, and the 6800 km (4200 mile) diameter planet is about 327 pixels across. North is at the top of the image. The MGS spacecraft pointed the camera at the center of the planet (near the dark, morning sunrise line, or terminator) at 23.6° N, 82.1° W. At this distance from Mars, only bright and dark markings resulting from variations in the amount and thickness of dust and sand are visible. The large dark marking stretching from the right center northward is Acidalia Planitia, a region of rock and sand with less dust on it than the area immediately to the south, Chryse Planitia. Both Viking Lander 1 and Pathfinder landed in the latter, bright area. In this low resolution image, some of the dark features resemble the "canals" seen prominently in maps created by astronomers of the 19th and early 20th century. Mariner 9 and Viking images show that most of these dark lines are associated with sand deposits that are trapped in rough areas.
Mars Global Surveyor was launched on November 7, 1996 and will enter Mars orbit on Thursday, September 11 around 6:30 PM PDT. The spacecraft will use atmospheric drag to reduce the size of its orbit. Mapping operations will begin in March 1998.
The MOC on MGS is a spare camera originally developed for the ill-fated Mars Observer mission. Malin Space Science Systems and the California Institute of Technology were responsible for development of both cameras. MSSS operates the MOC from its facilities in San Diego, CA, under contract to the Jet Propulsion Laboratory.