Credit: NASA/Malin Space Science Systems
Before we move on, now would be a good time to show just how good the optics have become on the various missions to Mars. Yesterday, we showed a photo taken of Mariner crater by Mariner 4. Malin Space Science Systems, which helped to build the Mars Orbiter Camera (MOC) on board Mars Global Surveyor (MGS), has an interesting comparison using Mariner crater over a 34-year span. This first picture is of Mariner crater taken by Mariner 4; Malin has added a white arrow to the photo that references the third picture (below).
Our second picture is of Mariner crater taken by the Viking 1 Orbiter back in February 1978. As you can see, the crater detail is crystal clear, especially of that linear ridge (part of Sirenum Fossae) that cuts diagonally across the bottom of the crater.
The last photo is some detail of the rim of Mariner crater taken by the MOC on March 18, 1999; remember, this is that tiny point indicated by the white arrow in the first photo above. The resolution of this photo to the first above is almost 400 times greater than what was capable back in the mid 60s. This view of the Mariner crater floor has a spatial resolution of 1.5 meters (5 feet) per pixel and covers an area only 1.5 km (0.9 mi) wide by 2.2 km (1.4 mi) long, whereas Mariner crater as a whole is 151 km wide.