Opportunity made its way back toward "Purgatory Dune" for a chance to explore its own tracks. During the drive the rover stopped along the way to study the soil at "North Dune."
Sol-by-sol summaries:
Sol 497 (June 16): This was the second sol of a two-sol plan. Today was dedicated to remote sensing, including panoramic camera usage with 13 filters and stares with the miniature thermal emission spectrometer.
Sol 498: On sol 498, Opportunity deployed its robotic arm to get a "taste" of the North Dune. The rover did this using both the microscopic imager and the alpha particle X-ray spectrometer. The next sol, the rover moved slightly back (about 40 centimeters or 1.3 feet) and then slightly forward (the same distance) in a move designed to place it on an optimal approach, ready to drive to its destination on Purgatory Dune. The last sol of this three-sol plan was again spent as a remote-sensing sol.
Sols 501 and 502: Opportunity had been trying to line itself up with the science target by performing arcs. Due to nature of this terrain, it had not been yawing as much as expected so its approach was slightly off. The team decided to have the rover try a turn in place. Engineers had been staying away from turning in place because Opportunity has a bad steering actuator on one wheel, and this makes turning in place more cumbersome. This turn in place, however, had some advantages because it was in the right direction and it was a small turn. The rover performed it perfectly.
The turn in place churned up soil in front of Opportunity. This made the immediate area in front of the rover more prone to slippage. Opportunity detected excessive slippage (more than 30 percent) when it attempted to perform the first of two 25-centimeter (9.8-inch) arcs. The visual odometery system detected that the first arc went only 17.1 centimeters (6.7 inches). This constituted a 32 percent slip. The engineers had limited the acceptable amount of slippage to 30 percent, so the rover was not commanded to perform the second arc. The next sol was a remote-sensing day.
Sols 503 and 504 (June 22 and 23): The team planned another drive consisting of three 25-centimeter (9.8-inch) arcs. This drive was calculated to bring the rover to its destination at Purgatory Dune.