A comparison of images taken by the Hubble Space Telescope Wide Field/Planetary Camera (HST/WFPC) and the Mars Global Surveyor Orbiter Camera (MGS/MOC) shows the progress of a regional dust storm within the Valles Marineris canyons on Mars. The first HST image (left), taken in mid-May, shows no dust within the canyons. The most recent HST image (center), taken on 27 June in support of the Mars Pathfinder landing activities, shows a dust storm filling part of the canyon system and extending into the chaotic terrains at the eastern end of the canyons. The MGS/MOC image (right), acquired on July 2, shows that bright dust continues to fill the valleys. However, it does not appear to have moved significantly north of the previously observed position, suggesting that the storm remains confined to the canyon region, and does not appear to directly threaten the Pathfinder landing site (small black circle).
The HST images shown here have been reduced in scale to match that of the MGS/MOC image. Although the HST is 10 times farther from Mars than MGS, its images are sharper because its resolving power is 15 times better than the MOC, and the light gathering area is almost 50 times greater. However, MGS is presently 45,000 times farther from Mars than it will be when the MOC begins its primary photography mission. At 400 km above the martian surface, the MOC wide angle camera will collect daily images at a resolution of 7.5 km/pixel, compared to HST's best of about 20 km/pixel. The narrow angle camera will observe portions of Mars at better than 1.5 m/pixel.
The Mars Global Surveyor is operated by the Mars Surveyor Operations Project managed for NASA by the Jet Propulsion Laboratory, Pasadena CA. The Mars Orbiter Camera is a duplicate of one of the six instruments originally developed for the Mars Observer mission. It was built and is operated under contract to JPL by an industry/university team led by Malin Space Science Systems, San Diego, CA.