Curiosity’s CheMin instrument uses X-ray diffraction to identify minerals in Martian rock and soil samples.
CheMin stands for Chemistry and Mineralogy. Curiosity drills or scoops material, delivers powdered sample into the instrument, and directs X-rays through it. Crystal structures diffract the rays at characteristic angles, producing a pattern that scientists can match to known minerals. The instrument can also estimate the abundance of those minerals.
CheMin’s first Martian analysis took place at the Rocknest site in October 2012. It identified minerals including feldspar, pyroxenes, and olivine, helping researchers compare Martian soil with weathered basaltic soils on Earth.
The other options perform different jobs: REMS monitors environmental conditions, SAM studies samples’ chemistry and gases, and ChemCam uses a laser to vaporize targets for spectroscopic analysis. CheMin is the Curiosity instrument specifically associated with X-ray diffraction.