Before leaving Adirondack, Spirit took images and collected miniature thermal emission spectrometer (Mini-Tes) data from the hole it ground with its rock abrasion tool (Rat).

BBC: NEWS | Science/Nature | Rover sets Mars distance record

So, the command was given to drill a second hole that was deep enough to push some cuttings into the tool's sample acquisition chamber.

BBC: Curiosity Mars rover takes historic drill sample