Eventually, though, the drill will go deep enough to push rock powder into the drill's sample-gathering chamber.

BBC: Curiosity Mars rover spins its rock drill

Scientists need to be sure that when the big hammer tool turns in a rock it breaks the surface into a useable powder that will not clog or damage the sample handling mechanism.

BBC: Curiosity Mars rover deploys its rock brush

Some of the powder will be used to scour the instruments to make sure no remnants from Curiosity are in the sample.

FORBES: Curiosity Drills A Hole On Mars