Determining the local abundance of Martian methane and its’ 13C/ 12C and D/H isotopic ratios for comparison with related gas and soil analysis on the 2011 Mars Science Laboratory (MSL) mission

Abstract

Understanding the origin of Martian methane will require numerous complementary measurements from both in situ and remote sensing investigations and laboratory work to correlate planetary surface geophysics with atmospheric dynamics and chemistry. Three instruments (Quadrupole Mass Spectrometer (QMS), Gas Chromatograph (GC) and Tunable Laser Spectrometer (TLS)) with sophisticated sample handling and processing capability make up the Sample Analysis at Mars (SAM) analytical chemistry suite on NASA’s 2011 Mars Science Laboratory (MSL) Mission. Leveraging off the SAM sample and gas processing capability that includes methane enrichment, TLS has unprecedented sensitivity for measuring absolute methane (parts-per-trillion), water, and carbon dioxide abundances in both the Martian atmosphere and evolved from heated soil samples. In concert with a wide variety of associated trace gases (e.g. SO 2, H 2S, NH 3, higher hydrocarbons, organics, etc.) and other isotope ratios measured by SAM, TLS will focus on determining the absolute abundances of methane, water and carbon dioxide, and their isotope ratios: 13C/ 12C and D/H in methane; 13C/ 12C and 18O/ 17O/ 16O in carbon dioxide; and 18O/ 17O/ 16O and D/H in water. Measurements near the MSL landing site will be correlated with satellite (Mars Express, Mars 2016) and ground-based observations.