This is from the NASA website in a press release:
On Saturday night, Aug. 18, ChemCam is expected to “zap” its first rock in the name of planetary science. It will be the first time such a powerful laser has been used on the surface of another world.
“Rock N165 looks like your typical Mars rock, about three inches wide. It’s about 10 feet away,” said Roger Wiens, principal investigator of the ChemCam instrument from the Los Alamos National Laboratory in New Mexico. “We are going to hit it with 14 millijoules of energy 30 times in 10 seconds.”