SAM is NASA's Mars Curiosity rover's onboard chemistry instrument suite or lab. Taking up more than half the science payload onboard the Curiosity rover, the instrument suite features chemical equipment similar to those found in scientific laboratories on Earth. Provided by NASA's Goddard Space Flight Center, Sample Analysis at Mars is designed to search for compounds of the element carbon, including methane, that are associated with life and explore ways in which they are generated and destroyed in the Martian ecosphere.

Consisting of three instruments - mass spectrometer, gas chromatograph, and tunable laser spectrometer, Sample Analysis at Mars is able to measure the abundances of other light elements, such as hydrogen, oxygen, and nitrogen, associated with life.

The mass spectrometer is designed to separate elements and compounds by mass for identification and measurement. The gas chromatograph heats soil and rock samples until they vaporize, and then separates the resulting gases into various components for analysis. The laser spectrometer measures the abundance of various isotopes of carbon, hydrogen, and oxygen in atmospheric gases such as methane, water vapor, and carbon dioxide. These measurements are accurate to within 10 parts per thousand.

Because these compounds are essential to life as is known to human, their relative abundances will be an essential piece of information for evaluating whether Mars could have supported life in the past or present.