Opportunity is showing no signs of middle age as it continues to work in "Endurance Crater." The rover has spent the last few sols inching farther down into the crater, making observations and pushing the limits. Managing resources as the rover's tilt angle changes is challenging and keeps the rover planning team very busy.
On sol 141 Opportunity completed post-rock abrasion tool Mossbauer spectrometer observations on the rock called "Tennessee." Having spent the last four sols investigating Tennessee, Opportunity stowed its arm and moved deeper into Endurance Crater. A 0.70-meter (2.3 feet) drive positioned the vehicle to begin observations on the first contact point, a transition between two different geologic layers. As it turns out, after arriving at the rover's new location and taking images, there appears to be not one contact point, but three contact points all within reach of the arm. Opportunity then performed 2.5 hours of remote observations using the panoramic camera and miniature thermal emission spectrometer. The rover then went into deep sleep mode for the night.
On sol 142 Opportunity begin another series of microscopic imager observations on three different targets: "Bluegrass," "Siula Grande" and "Churchill." The rover then performed alpha particle X-ray spectrometer and Mossbauer spectrometer integrations overnight.
On sol 143 Opportunity again used its rock abrasion tool, but not without some consternation from the uplink team. In order to grind using the rock abrasion tool, a minimum of force must be used to push the tool onto the target. With the vehicle tilted 23.2 degrees, there was concern that applying too much force could cause the vehicle to lose traction on the slope and slide farther into the crater, possibly damaging the arm. Concerns were pacified when the rock abrasion tool operation worked flawlessly, abrading approximately 3 millimeters (about
0.12 inches) into the rock called "Cobble Hill."