Opportunity is exploring 'Marathon Valley' on the rim of Endeavour crater, investigating outcrops for evidence of clay minerals.

The rover is close to completing its investigations within Marathon Valley. On Sol 4400 (June 9, 2016), Opportunity continued with the in-situ (contact) investigation of the area that was scuffed by the rover wheel.

The rover collected a Microscopic Imager (MI) mosaic of the 'red pebble' target and then placed the Alpha Particle X-ray Spectrometer (APXS) on the same for a multi-hour integration.

On Sols 4402 and 4403 (June 11 and 12), Opportunity performed a 2-sol plan each with MI imagery and further offset APXS placements to map out the elemental constituents of the target.

On Sol 4404 (June 13, 2016), the rover bumped back, collected 13-filter images of the work area, then bumped further back, totaling 4.6 feet (1.4 meters).

With the work complete at this site, Opportunity drove away on Sol 4405 (June 14, 2016), with a 62-feet (19-meter) drive heading towards the center of the area where a clay mineral signature has been observed from orbit.

As of Sol 4405 (June 14, 2016), the solar array energy production is 658 watt-hours with an atmospheric opacity (Tau) of 0.645 and a solar array dust factor of 0.752.

Total odometry is 26.60 miles (42.81 kilometers), more than a marathon.