Photograph of the planet Mars taken at 8:52 p.m. Pacific Daylight Time on July 26 by the high resolution, narrow-angle telescope of the Mars Observer Camera. At that time, the Mars Observer spacecraft was 5.8 million kilometers (3.6 million miles) and 28 days from its encounter with Mars. The resolution in this image is approximately 21.5 km (13.4 mi) per picture element and Mars, roughly 6800 km (4200 miles) in diameter, is about 315 picture elements across. North is to the top of the image; the south pole is near the bottom but in shadow. The sunrise line (terminator) stretches across the morning hemisphere from lower right to upper left. At this distance from Mars, only bright and dark markings resulting from variations in the amount and thickness of dust and sand are visible. Toward the bottom of the picture is a bright, roughly circular area called Hellas, an impact basin 2000 km (1250 ml) across. The dark area in the center of the frame is Syrtis Major, a region of volcanic plains and dark sand dunes. At the top of the photograph is Nilosyrtis, an area of buttes, mesas and box canyons reminiscent of the deserts of the southwest United States. Launched on Sept. 25, 1992, Mars Observer will enter Mars orbit on Tuesday, Aug. 24, at about 1:30 p.m. PDT. In-orbit engineering checkout of the camera is scheduled to begin Sept. 16. The camera and six other investigations begin mapping operations from a circular orbit just 400 km (248 mi) above the surface on Dec. 16. The Mars Observer Camera was developed by and is operated under contract to Jet Propulsion Laboratory by an industry/university team led by Malin Space Science Systems, San Diego, Calif. Photographs from the landers and orbiters surpassed expectations in quality and quality. The total exceeded 4,500 from the landers and 52,000 from the orbiters. The landers provided the first close-up look at the surface, monitored variations in atmospheric opacity over several Martian years, and determined the mean size of the atmospheric aerosols. The orbiter cameras observed new and often puzzling terrain and provided clearer detail on known features, including some color and stereo observations. Viking's orbiters mapped 97 percent of the Martian surface.
