But what is it?

Here's an explainer, as well as more details about the mission.

ChemCam can look at rocks and soils from a distance, fire a laser to vaporize the materials and analyze them with an on-board spectrograph that measures the composition of the resulting plasma. NASA says ChemCam can also use the laser to do less destructive things, such as clear away dust from Martian rocks as well as use a remote camera to acquire extremely detailed images.

Roger Wiens, ChemCam principal investigator at the Los Alamos National Laboratory, gave a tutorial on how the instrument works at a recent news conference.

"Curiosity's remote sensing instrument [is] designed to make a large number of rapid measurements in some sense to help guide the rover to the most interesting samples," he said.