Opportunity is exploring Marathon Valley on the rim of Endeavour crater, searching specific outcrops for evidence of clay minerals. The rover is currently conducting an in-situ (contact) science investigation on an outcrop called "Pierre Pinaut".

On Sol 4360 (April 29, 2016), after some Pancam color imaging and completing an Alpha Particle X-ray Spectrometer (APXS) measurement on the outcrop, Opportunity used the Rock Abrasion Tool (RAT) on the robotic arm to brush clean the surface of the rock and placed the APXS back down again.

On that same sol, another imaging command hung, or was not executed, but was cleared in the post sequence cleanup.

On Sol 4361 (April 30, 2016), the robotic arm moved out of the way to allow clear imaging of the brushed surface with the Pancam color camera. Opportunity collected more Pancam color panoramas on the next sol.

On Sol 4363 (May 2, 2016), the same brushed rock was now ground with the RAT to a depth of about 0.04 inches (1 millimeter) and the APXS placed back down again for a post-grind measurement.

On Sol 4364 (May 3, 2016), another incomplete camera request prevented collecting Microscopic Images (MIs). Again the "stuck" image was cleared and operations continued with more Pancam panoramas.

The project continues to investigate the camera hanging issue and has developed a process to clear the hung camera as soon as it occurs, allowing all subsequent imaging to proceed.

As of Sol 4364 (May 2, 2016), the solar array energy production is 645 watt-hours with an atmospheric opacity (Tau) of 0.508 and a solar array dust factor of 0.774.

Total odometry is 26.58 miles (42.78 kilometers), more than a marathon.