Rock Abrasion Tool (RAT) for removing weathered rock surfaces and exposing fresh material for characterization; Some Martian rock surfaces are likely to be dust-covered, coated, weathered, or otherwise unrepresentative of the rock's interior. For this reason, the payload includes a Rock Abrasion Tool (RAT). The RAT is carried on the rover's instrument arm. When placed against a rock, the RAT uses mechanical grinding heads to remove 5 millimeters of material over a circular area 45 millimeters in diameter. The area of fresh material exposed is large enough to be investigated in detail using all of the instruments on the payload.