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 target dubbed 'Pierre Pinaut.'

The imaging problems we were experiencing previously were traced to a sequencing error, and Opportunity has returned to normal operations as of the Sol 4367 (May 6, 2016), plan.

In that plan we recaptured the Microscopic Image (MI) mosaic of the Rock Abrasion Tool (RAT) grind from Sol 4363 (May 2, 2016), and discovered that the grind had not gone deep enough.

Therefore, a further grind (to a desired depth of 2-3 millimeters) was performed in the Sol 4370 (May 9, 2016), plan. This appears to have been successful and an MI mosaic of the new RAT hole is planned for Sol 4372 (May 11, 2016).

In addition, multiple APXS integrations have been performed on both the previous and current RAT holes during this period.

As of Sol 4371 (May 10, 2016), the solar array energy production is 653 watt-hours with an atmospheric opacity (Tau) of 0.458 and a solar array dust factor of 0.752.

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