Mission controllers were confident the rover’s drill and coring bit had operated properly. So, they concluded, it was the rock that had misbehaved. Called Roubion, this first target is what researchers call a paver stone — flat, polygonal rocks they believe are some of the oldest in the crater. But such rocks are so old and weathered that their crumbly texture thwarted sampling attempts.
To find a better target, controllers drove to a ridge called Citadelle, with outcroppings of rocks very different from the paver stones. And on Sept. 2, Perseverance successfully completed its first sample collection. This time, images from the rover showed the rock core, a bit wider than a pencil, snug in its sample tube.