Curiosity bored a hole about 0.5 inches (1.3 centimeters) deep into a target rock on Monday (Feb. 26), during the trial run of a new, jerry-rigged drilling technique, NASA officials said.
https://www.space.com/39847-mars-rover-curiosity-drill-test.html
Lovely space brilliant work
I do not understand why it took 2 years to drill again. Did they had an issue with the drill?