'Coronation' Rock on Mars This mosaic image with a close-up inset, taken prior to the test, shows the rock chosen as the first target for NASA's Curiosity rover to zap with its Chemistry and Camera (ChemCam) instrument. ChemCam fired its laser at the fist-sized rock, called "Coronation" (previously “N165”), with the purpose of analyzing the glowing, ionized gas, called plasma, that the laser excites.