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ChemCam fires an invisible laser, depicted here as the solid green line, in a series of pulses at a target rock. Electrons within the target then become excited, decay, and emit light, resulting in a flash of light visible to the human eye.

ChemCam receives this light, depicted as the dashed green line, with the built-in telescope and analyzes it with a spectrometer, which identifies the types of atoms within the target. ChemCam can distinguish different elements in the target sample because each chemical element has its own unique light signature.