The mission of the one-ton nuclear powered Curiosity rover that landed in Gale crater in August of 2012 was to explore the habitability of ancient Mars. Since that time, Curiosity has been systematically exploring an environment that ~3.5 billion years ago was a long-lived lake that had formed in an impact crater hundreds of millions of years earlier.<br/>The Sample Analysis at Mars (SAM) instrument suite on the Curiosity rover has enabled a range of geochemical investigations including: (1) atmospheric composition (including methane) and its seasonal variation,  (2) isotopic composition of gases in the present atmosphere and gases released from solid samples, (3) dating of rock formation ages using K/Ar measurements, (4) cosmic radiation exposure ages from noble gases released from minerals, (5) characteristics of clays, perchlorates, sulfates, and hydrated minerals from evolved gas analysis (EGA), and (6) identification of organic compounds extracted from soils and rocks. SAM geochemical measurements are robustly complemented by data from the same samples from the x-ray diffractometer (CheMin) and the alpha-particle x-ray spectrometer (APXS).<br/>The first in situ detection of organic compounds from the surface of Mars was of chlorobenzene and three chlorinated alkanes [1] from the Cumberland mudstone. Sulfur compounds such as thiophene, methyl and di-methyl thiophene, dimethylsulfide, and methanethiol have since been discovered as well as fragments of other aromatic and alkyl compounds produced in the higher temperature releases from some samples. These results demonstrate that parts per million of carbon containing compounds can survive the combustion caused by the oxygen from the decomposition of perchlorates and oxychlorine compounds in the SAM ovens. These first steps in unraveling the nature of organic compounds on Mars and the multiple mechanism responsible for their degradation pave the way for a more direct search for extinct or extant life on this planet.<br/>

Discovery of organics on Mars with the SAM experiment on the Curiosity rover

2019 Spring National Meeting

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