Before conjunction, they deliberately...
...pushed the arm into the sand. Idea was to image it before and after, since the rover would not move for all that time. They would be able to see if wind or anything changed the impression over time.
Problem was, they picked up a dirt clod or something that they fear will affect the mossbauer use over that magnet experiment. They intended to do extensive moss readings while parked during conjunction.
Not sure how all this stuff turned out. And it's possible, I've got my rovers mixed up.