And on Mars, really

From a NASA / JPL press release:

NASA Rover Nears Martian Bowl Goal

NASA's Mars rover Opportunity is closing in on what may be the grandest overlook and richest science trove of its long mission.

During the next two weeks, the robotic geologist is likely to reach the rim of a hole in the Martian surface wider and deeper than any it has visited. The crater, known as "Victoria," is approximately 750 meters (half a mile) wide and 70 meters (230 feet) deep.

Images from NASA's Mars Global Surveyor orbiter show the crater walls expose a stack of rock layers approximately 30 to 40 meters (100 to 130 feet) thick. Opportunity will send back its initial view into the crater as soon as it gets to the rim. Scientists and engineers will use Opportunity's observations from points around the rim to plot the best route for entering the crater.

"Victoria has been our destination for more than half the mission," said Ray Arvidson of Washington University, St. Louis. Arvidson is deputy principal investigator for Opportunity and its twin rover, Spirit. "Examination of the rocks exposed in the walls of the crater will greatly increase our understanding of past conditions on Mars and the role of water. In particular, we are very interested in whether the rocks continue to show evidence for having been formed in shallow lakes."

The NASA rovers have been exploring landscapes on opposite sides of Mars since January 2003. Their prime missions lasted three months. Both rovers are still investigating Mars' rocks, soils and atmosphere after more than 30 months. Opportunity works in a region where rock layers hundreds of meters or yards in thickness cover older, heavily cratered terrain.

View Opportunity's mission maps linked here at JPL.