The Opportunity mission is now the first human enterprise to exceed marathon distance of travel on another world.

Opportunity is on the west rim of Endeavour Crater near 'Marathon Valley', a putative location for abundant clay minerals. The rover is approaching a feature called 'Spirit of St. Louis Crater' at the entrance to Marathon Valley.

On Sol 3964 (March 19, 2015), the flash-memory file system was reformatted using new flight software. The reformat was successful. The rover is again using flash for nonvolatile data storage. On Sol 3966 (March 21, 2015), Opportunity began approaching the Spirit of St. Louis Crater with a 177-foot (54-meter) drive, avoiding some obstacles along the way. The drive was preceded with some targeted Pancam imagery and followed by a Navcam panorama, which is typical practice when driving.

On Sol 3968 (overnight March 23 to March 24), Opportunity made history. The rover the rover drove 154 feet (46.9 meters) in a dog leg around the crater. With that drive, Opportunity exceeded the distance for a marathon (26.219 miles or 42.195 kilometers). On Sol 3959 (March 24), the rover continued to advance with a 28-foot (8.5-meter) approach to a light-toned rock outcrop.

As of Sol 3969, the solar array energy production was 610 watt-hours with an atmospheric opacity (Tau) of 0.678 and a solar array dust factor of 0.717.

Total odometry as of Sol 3969 (March 24, 2015) is 26.241 mile (42.230 kilometers).