Curiosity is now officially coloring outside the lines. The rover recently drove out of the area NASA had initially demarcated as safe terrain for its 2012 landing in Gale Crater.
The landing ellipse established by NASA measured approximately four miles wide and 12 miles long (7 x 20 km). THe HiRISE camera on NASA's Mars Reconnaissance Orbiter took a shot of the rover as it drove across the boundary.
The landing ellipse is the area within which the rover had a very high probability of touching down when it arrived at Mars on Aug. 5, 2012, PDT (Aug. 6, UTC). The area needed to meet requrements for providing access to scientifically interesting sites while presenting few landing hazards, such as steep slopes or large boulders. Many areas of scientific interest have slopes ineligible for landing safety, and Curiosity was designed to have the capability of driving far enough to get to slopes ouside of the landing ellipse. Since landing, Curiosity has driven slightly more than 5 miles (8 kilometers).
Here's the view from the ground via Ken Kramer of Universe Today: