In this interview, Darby Dyar explains how Curiosity rover’s ChemCam instrument will probe the rocks of Mars to learn about the planet from the inside out. The Chemistry & Camera (ChemCam) will use a laser to target selected rocks, creating an ionized, glowing plasma that will be used to analyze their composition. Darby Dyar, a geochemist at Mount Holyoke College, is one of the scientists using ChemCam to search Martian minerals for hydrogen and water.