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The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC), operating in martian orbit since September 1997, acquired an image of the Mars Exploration Rover (MER-A), Spirit, on 19 January 2004. The Spirit/Columbia Memorial Station is clearly seen as a bright feature in the image, as are the parachute and backshell from which Spirit was detached during the landing on 4 January 2004 (see inset for annotation). Also evident is a dark scar on the rim of a crater to the northeast of the lander; this dark marking was not present prior to landing, and is believed to have been caused by the impact of Spirit's heatshield. The lander is white because the data received from Mars were saturated at this location--that is, the lander was so much brighter than the surrounding terrain that the camera saw it as a white object.
The image shown here is located in Gusev Crater near 14.7°S, 184.6°W. North is up and sunlight illuminates each image from the left. The MOC image was acquired near 2 p.m. local time on Mars. The lander appears white because the DNs (data numbers) received from Mars for the lander were 255--the maximum possible (i.e., the lander was saturated). The values were saturated because of the high sun elevation angle and the fact that the lander and parachute are covered with highly reflective, light-toned materials (as seen in the lander portrait released on 21 January 2004).