Opportunity is exploring 'marathon valley' on the rim of endeavour crater, trying to identify specific outcrops for evidence of clay minerals. The rover has been investigating the surface target, called 'pierre pinaut.'

The rover experienced an anomalous camera fault on sol 4350 (april 19, 2016), during a microscopic image (mi) mosaic, so the activities in that plan did not complete.

Opportunity then performed two sets of diagnostics on sol 4352 (april 21, 2016). The mi images completed normally and several panoramic camera (pancam) panoramas taken before and after the mi camera anomaly completed normally.

On sol 4354 (april 23, 2016), the original mi activity using the robotic arm from sol 4350 (april 19, 2016), was repeated successfully which included the placement of the alpha particle x-ray spectrometer (apxs). More pancam panoramas were collected on the next sol.

On sol 4357 (april 26, 2016), the rock abrasion tool (rat) on the robotic arm was used to brush the surface target, followed by the placement of the apxs for a long integration.

As of sol 4357 (april 26, 2016), the solar array energy production is 618 watt-hours with an atmospheric opacity (tau) of 0.541 And a solar array dust factor of 0.764.

Total odometry is 26.58 Miles (42.78 Kilometers), more than a marathon.