The Mars Global Surveyor spacecraft successfully began its prime mapping mission at 4 p.m. PST March 8, 1999. The image above shows the shadow of the martian moon, Phobos, which has been captured in many recent wide angle camera views of the red planet by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC). Designed to monitor changes in weather and surface conditions, the wide angle cameras are also proving to be a good way to spot the frequent solar eclipses caused by the passage of Phobos between Mars and the Sun.

The first figure (above), shows wide angle red (left), blue (middle), and color composite (right) views of the shadow of Phobos (elliptical feature at center of each frame) as it was cast upon western Xanthe Terra on August 26, 1999, at about 2 p.m. local time on Mars. The image covers an area about 250 kilometers (155 miles) across and is illuminated from the left. The meandering Nanedi Valles is visible in the lower right corner of the scene. Note the dark spots on three crater floors--these appear dark in the red camera image (left) but are barely distingished in the blue image (middle), while the shadow is dark in both images. The spots on the crater floors are probably small fields of dark sand dunes.

New images from the mapping phase will be posted on the web each Tuesday and Thursday at MSSS and NASA's Planetary Photojournal.