SAM, I AM!

SAM is a suite of three instruments totaling 40 kg, located in the Curiosity rover's interior: a 6-column Gas Chromatograph (GC), a Quadrupole Mass Spectrometer (QMS), and a Tunable Laser Spectrometer (TLS). These instruments are coupled through solid and gas processing systems to provide complementary information on the same samples. Each sample may be analyzed by one, two, or all three of the SAM instruments.

The GC has six complementary chromatographic columns. The GC assembly sorts, measures, and identifies gases it separates from mixtures of gases by pushing the mixed gases through long, narrow tubes (wound into coils) with a stream of helium gas. It sorts the gas molecules by weight: they emerge from the tube in order from lightest (out first) to heaviest (out last). Once the gases are sorted, the GC can direct quantities of the separated gases into the QMS or TLS for further analysis.

The QMS identifies gases by the molecular weight and electrical charge of their ionized states. It fires high-speed electrons at the molecules, breaking them into fragments. It then sorts the fragments by weight with AC and DC electric fields. The spectra generated by the QMS detector uniquely identify the molecules in the gases.

The TLS uses absorption of light at specific wavelengths to measure concentrations and isotope ratios of specific chemicals important to life: methane, carbon dioxide, and water vapor.

Sieved powdered rock and regolith samples are delivered to small cups in SAM's Sample Manipulation System (SMS) by Curiosity's robotic arm through the solid sample inlet tubes. Atmospheric samples are collected through the atmospheric inlets.

The SMS has a wheel of 74 small cups where solid samples are accepted prepared for analysis in one of SAM's three instruments. 59 of the cups are quartz cups are small ovens that can be heated to very high temperatures to pull gases from the powdered samples. 9 sealed cups are filled with chemical solvents for lower- temperature wet chemistry experiments designed to search for certain polar organic compounds. The other 9 cups contain calibration materials.

The chemical separation and processing laboratory includes valves, pumps, carrier-gas reservoirs and regulators, pressure monitors, chemical scrubbers, and two ovens that can heat samples to about 1,000 degrees Celsius (1,800 degrees Fahrenheit). The wide range pump spins at 100,000 revolutions per minute to transfer gas out of the system between analyses of different samples.