Opportunity continued its exploration of “Endurance Crater” the past five sols, and is now roughly 11 meters (about 36 feet) into the crater. The only drive during this period was on sol 171, when the rover turned around, backed down across the slope, then turned towards a feature called “Razorback.”

Razorback is a vertical fracture in the local bedrock that may contain sediment deposits with clues about the water history in this area. The team’s near-term plan is to follow Razorback farther down into the crater, at least another 7 meters (about 23 feet).

Slopes at Opportunity’s present location and immediately downward are in the 15- to 20-degree range, which is a comfortable range for driving.

Despite the gentler slopes, the slip is still difficult to predict, as evidenced by the sol 171 drive. In that series of maneuvers, the rover slipped roughly 20 centimeters (about 8 inches) more than expected.

Opportunity ended up farther downslope than desired, with what appears to be a broken piece of Razorback within arm’s reach. The decision was made to stay put and use the suite of science instruments on sols 173 and 174 to see if this rock, dubbed “Arnold Ziffel” (after a pig on the TV series, “Green Acres”), was different from the surrounding bedrock.

A minor concern about a temperature sensor on the rock abrasion tool that is functioning intermittently has been resolved. This sensor is used to determine the starting temperature of the tool’s motors, which in turn is used to set motor control parameters.

The rock abrasion tool team plans to use a nearby temperature sensor on the arm turret for the same purpose and is not expecting the loss of this temperature sensor to affect the rover’s ability to use the tool.