The Second Science Phasing Orbits (SPO-2) period of the Mars Global Surveyor mission began at the end of May 1998. These orbits are morning orbits. That is, the local time on the planet beneath Mars Global Surveyor is in the morning. During the first part of June 1998, the local time on the ground was approximately 9:30 a.m. The Mars Orbiter Camera (MOC) has observed that this time of day is quite cloudy this year.

Clouds have thus posed a real challenge for the MOC team, who are targeting high resolution images almost every day. Many of the high resolution images that were returned to Earth in early June 1998 were nearly white with clouds and haze. Very little detail could be seen on the ground.

The above picture illustrates one of the better cloudy images obtained by MOC. The haze was too thick to show much detail on the surface in the raw image, but in this case at least a dark lineation could be seen in part of the image. The full frame was nearly white everywhere except in the vicinity of the dark lineation. The MOC image, #35003, was obtained on Mars Global Surveyor's 350th orbit about the planet. The picture was taken around 4:00 a.m. PDT on June 7, 1998. The center of this subframe is at 8.03°N, 194.30°W. The dark lineation is one of the Cerberus Rupes--a set of dark lines (ridges or fractures) that cross the region southeast of the Elysium volcanic rise.

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.