It is northern summer on Mars and clouds are very common over the famous Tharsis volcanoes during the afternoon. At the far left, a white patchy cloud denotes the location of Olympus Mons. Ascraeus Mons is under the brightest cloud toward the center left, but the volcanoes Pavonis Mons and Arsia Mons (toward lower left below Ascraeus Mons) have much less cloud cover. The patch of clouds toward the upper left mark the location of the Alba Patera volcano. The Valles Marineris trough system--so long that it would stretch across North America--is seen in the lower third of this picture. This is a color composite of 9 red and 9 blue image strips taken by the Mars Global Surveyor Mars Orbiter Camera on 9 successive orbits from pole-to-pole during the calibration phase of the mission in March 1999. The color is computer-enhanced and is not shown as it would actually appear to the human eye.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.